MRI evaluation of neoadjuvant low-dose fractionated radiotherapy with concurrent chemotherapy in patients with locally advanced breast cancer

Objectives

We address the diagnostic performance of breast MRI and the efficacy of neoadjuvant radiochemotherapy (NRC) treatment (NRC protocol) vs conventional neoadjuvant chemotherapy (NAC) in patients with locally advanced breast cancer.

Methods

The NRC protocol consists of six anthracycline/taxane cycles and concomitant low-dose radiotherapy on breast tumour volume. Breast MRI was performed at baseline and after the last therapy cycle in 18 and 36 patients undergoing the NRC protocol or conventional NAC (propensity matching).

Results

In both groups, we observed reduced tumour dimensions after the last cycle (p<0.001), and the response evaluation criteria in solid tumours (RECIST) class directly correlated with the tumour regression grade class after the last cycle (p<0.001). Patients in the NRC group displayed a higher frequency of complete/partial response than those in the NAC group (p=0.034). 17 out of 18 patients in the NRC group met the criteria for avoiding mastectomy based on final MRI evaluation. The RECIST classification displayed a superior diagnostic performance in the prediction of the response to treatment [area under the receiver operating characteristic curve (AUC)=0.72] than time-to-intensity curves and apparent diffusion coefficient (AUC 0.63 and 0.61). The association of the three above criteria yielded a better diagnostic performance, both in the general population (AUC=0.79) and in the NRC and the NAC group separately (AUC=0.82 and AUC=0.76).

Conclusions

The pathological response is predicted by MRI performed after the last cycle, if both conventional MRI and diffusion imaging are integrated. The NRC treatment yields oncological results superior to NAC.

Advances in knowledge

MRI could be used to establish the neoadjuvant protocol in breast cancer patients.Neoadjuvant chemotherapy is currently widely employed in patients with locally advanced breast cancer (LABC) in order to improve the rate of breast-conserving surgery (up to 98% of patients) and systemic control of the disease [1,2]. The coupling of pre-operative radiotherapy (RT) cycles with neoadjuvant chemotherapy has been proposed for other cancer types. In particular, taxanes could have a synergistic effect with RT when administered concurrently [3-5]. Nonetheless, few data are currently available on the efficacy of concurrent neoadjuvant RT in patients with LABC, although evidence exists that such a strategy is safe and feasible [6], and is supported by preliminary investigations [7,8]. Radiation doses below 0.5 Gy have been demonstrated to enhance the effectiveness of continuous-infusion taxanes. This phenomenon has been termed low-dose hyper-radiosensitivity [9,10].MRI is a reliable tool to evaluate the breast cancer response to chemotherapy by measuring tumour diameter changes and by assessing the viability of residual tumour areas [11-13]. Nevertheless, MRI may under- or overestimate the burden of residual tumour by confounding a fibrotic scar with viable tumour tissue, or vice versa. Diffusion-weighted imaging (DWI) has been shown in such contexts to improve the diagnostic performance of MRI [14]. It has not been clarified whether MRI retains its diagnostic performance even in the context of breast RT. The latter is known to trigger tissue oedema, which may potentially impair the diagnostic accuracy [15,16]. The purpose of the present work is to ascertain (1) the diagnostic performance of MRI and DWI-MRI in the context of concurrent low-dose fractionated RT (LD-FRT) and chemotherapy in the prediction of response to neoadjuvant treatment; (2) whether the adoption of concurrent neoadjuvant LD-FRT and chemotherapy yields better oncological results in LABC than neoadjuvant chemotherapy alone.     

Prediction of pathological complete response of breast cancer patients undergoing neoadjuvant chemotherapy: usefulness of breast MRI computer-aided detection

Objective:

To evaluate the usefulness of MR computer-aided detection (CAD) in patients undergoing neoadjuvant chemotherapy for prediction of the pathological complete response of tumours.

Methods:

148 patients with breast cancer (mean age, 47.3 years; range, 29–72 years) who underwent neoadjuvant chemotherapy were included in our study. They underwent MRI before and after neoadjuvant chemotherapy, and we reviewed the pathological result as the gold standard. The computer-generated kinetic features for each lesion were recorded, and the features analysed included “threshold enhancement” at 50% and 100% minimum thresholds; degree of initial peak enhancement; and enhancement profiles comprising lesion percentages of washout, plateau and persistent enhancement. The final pathological size and character of tumours were correlated with post-chemotherapy mammography, ultrasonography and MR CAD findings. Kruskal–Wallis test and intraclass correlation coefficient were used to analyse the findings.

Results:

We divided the 148 patients into complete pathological response and non-complete pathological response groups. A complete pathological response was defined as no histopathological evidence of any residual invasive cancer cells in the breast or axillary lymph nodes. 39 patients showed complete pathological response, and 109 patients showed non-complete pathological response. Between enhancement profiles of MR CAD, plateau proportion of tumours was significantly correlated with the pathological response of tumours (mean proportion of plateau on complete pathological response group was 27%, p = 0.007).

Conclusion:

When plateau proportion of tumours is high, we can predict non-complete pathological response of neoadjuvant chemotherapy.

Advances in knowledge:

MR CAD can be a useful tool for the assessment of response to neoadjuvant chemotherapy and prediction of pathological results.In the early 1980s, neoadjuvant chemotherapy was introduced to improve outcomes in patients with advanced breast cancer.¹ This therapeutic method has been known for its fascinating advantages. Large and advanced breast cancers might be downstaged for conservative surgery rather than mastectomy. It also offers an improved survival rate. Furthermore, tumour response may be assessed in vivo by measuring tumour size. As a result, ineffective chemotherapy can be stopped and patients can avoid unnecessary toxicity.^2,3 Previous studies have shown that the size of residual tumours and the response of a tumour to neoadjuvant chemotherapy are related to the recurrence-free survival rate.^4–8 It was also exhibited^8,9 that neoadjuvant chemotherapy could lead to a pathological complete response (pCR) in up to 30% of patients with breast cancers, and these patients showed a better survival outcome than patients with residual cancers. This result emphasizes that prediction of chemotherapeutic effects before treatment could be critical for a successful cancer treatment.Pathological correlation with MRI has demonstrated greater sensitivity for evaluating breast cancers than do conventional imaging methods such as mammography and ultrasonography. MRI can predict the size and extent of lesions, including margins, with sensitivity near 100%.¹⁰ It also accurately evaluates residual tumour and better determines chemotherapeutic response. This imaging method could be beneficial for evaluation of response to neoadjuvant chemotherapy. As a result, it might enable physicians to optimize treatment regimens both early in the course of chemotherapy and post-operatively and to offer more opportunities for breast conservation.¹¹However, breast MRI requires more time for image processing and interpretation than do other conventional methods and has demonstrated variable specificity. To overcome these limitations, computer-aided detection (CAD) programs for breast MRI are widely used. These systems have the potential to improve efficiency of breast MRI and reduce the number of false-positive diagnoses.¹² CAD may not only improve consistency and detection rate but also provide new methods of analysis that are not available with manual interpretation such as quantitative measurement of kinetic curve thresholds.¹³ But, a previous study has shown that CAD was less accurate than a radiologist in the assessment of tumour size in patients with breast cancer undergoing neoadjuvant chemotherapy.¹⁴ Other research reported that CAD is sufficiently accurate for the assessment of the extent of residual tumours, but the assessment by a radiologist and CAD showed a fair-to-poor agreement for assessment of response to chemotherapy.¹⁵ However, controversy remains as to whether CAD is accurate for MRI of patients with breast cancer who were treated with neoadjuvant chemotherapy.Therefore, the purposes of this study were to retrospectively evaluate whether MRI parameters assessed with CAD are associated with the pCR of tumours, and to evaluate the accuracy of CAD in breast MRI for the assessment of the extent of residual tumours in patients undergoing neoadjuvant chemotherapy for breast cancer.     

Correlation between mammographic and sonographic findings and prognostic factors in patients with node-negative invasive breast cancer

Objectives

The purpose of this study was to correlate sonographic and mammographic findings with prognostic factors in patients with node-negative invasive breast cancer.

Methods

Sonographic and mammographic findings in 710 consecutive patients (age range 21–81 years; mean age 49 years) with 715 node-negative invasive breast cancers were retrospectively evaluated. Pathology reports relating to tumour size, histological grade, lymphovascular invasion (LVI), extensive intraductal component (EIC), oestrogen receptor (ER) status and HER-2/neu status were reviewed and correlated with the imaging findings. Statistical analysis was performed using logistic regression analysis and intraclass correlation coefficient (ICC).

Results

On mammography, non-spiculated masses with calcifications were associated with all poor prognostic factors: high histological grade, positive LVI, EIC, HER-2/neu status and negative ER. Other lesions were associated with none of these poor prognostic factors. Hyperdense masses on mammography, the presence of mixed echogenicity, posterior enhancement, calcifications in-or-out of masses and diffusely increased vascularity on sonography were associated with high histological grade and negative ER. Associated calcifications on both mammograms and sonograms were correlated with EIC and HER-2/neu overexpression. The ICC value for the disease extent was 0.60 on mammography and 0.70 on sonography.

Conclusion

Several sonographic and mammographic features can have a prognostic value in the subsequent treatment of patients with node-negative invasive breast cancer. Radiologists should pay more attention to masses that are associated with calcifications because on both mammography and sonography associated calcifications were predictors of positive EIC and HER-2/neu overexpression.The three strongest prognostic factors in invasive breast cancer are widely accepted to be lymph node stage, histological grade and the size of histologically invasive cancer [1–4]. Axillary lymph node stage is an important prognostic factor in invasive breast cancer: the prognosis progressively worsens with an increasing number of involved nodes. Although controversial, micrometastatic disease continues to have clinical significance. Most series have shown that nodal micrometastasis appears to have a more or less adverse effect on disease-g0ree and overall survival [5]. The three strongest prognostic factors in invasive breast cancer provide more valuable information when taken into account altogether than when any single individual factor is used alone. The Nottingham Prognostic Index (NPI) uses these three factors and has been externally validated by several studies [2, 6–8]. In addition, histological grade, tumour size and oestrogen receptor (ER) status are usually used as significant factors in guiding adjuvant systemic chemotherapy in node-negative patients [9].Lymphovascular invasion (LVI) shows a clear relationship with nodal status [10–13] and local recurrence [12, 13]. LVI is also related to distant metastasis and overall survival in node-negative breast cancer [14, 15]. Patients with breast cancers that exhibit a high proportion of intraductal components have a higher risk of local recurrence after conservative surgery [16, 17]. Hence, accurate evaluation of intraductal spread is considered to be a key issue in determining tumour margins before planning breast-conserving surgery [18]. HER-2/neu overexpression in node-negative cancers is related to disease relapse and to disease-related death, regardless of tumour size, histological grade and ER status [19].In terms of treatment, most patients with node-positive invasive breast cancers measuring greater than 2 mm are offered adjuvant chemotherapy, with additional hormone therapy or trastuzumab (Herceptin) based upon necessity according to their hormone receptor and HER-2/neu status. On the other hand, patients with node-negative invasive cancer might not be offered adjuvant therapy, adjuvant hormone therapy or chemotherapy depending on the size, LVI, histological grade, their hormone receptor responsiveness and HER-2/neu status, and their age [20]. Therefore, in patients with node-negative breast cancers, knowing the hormone receptor and HER-2/neu status, histological grade and extent of LVI is very important in guiding the treatment plan and determining the prognosis.Several studies have looked at the correlation between imaging findings and prognostic factors [18, 21–27]. To our knowledge, however, no report has correlated imaging findings in node-negative invasive breast cancers that were analysed according to the Breast Imaging Report and Data System (BI-RADS) lexicon with prognostic factors. The purpose of our study was to correlate sonographic and mammographic findings with prognostic factors in patients with node-negative invasive breast cancer and to determine whether or not the imaging findings could have prognostic value. We also determined the relative accuracy of mammography and sonography in evaluating the extent of disease in patients with node-negative invasive breast cancer.     

Primary vaginal cancer: role of MRI in diagnosis,staging and treatment

Primary carcinoma of the vagina is rare, accounting for 1–3% of all gynaecological malignancies. MRI has an increasing role in diagnosis, staging, treatment and assessment of complications in gynaecologic malignancy. In this review, we illustrate the utility of MRI in patients with primary vaginal cancer and highlight key aspects of staging, treatment, recurrence and complications.The incidence of primary vaginal cancer increases with age, with approximately 50% of patients presenting at age greater than 70 years and 20% greater than 80 years.¹ Around 2890 patients are currently diagnosed with vaginal carcinoma in the USA each year, and almost 30% die of the disease.² The precursor for vaginal cancer, vaginal intraepithelial neoplasia (VAIN) and invasive vaginal cancer is strongly associated with human papillomavirus (HPV) infection (93%).^3,4 In situ and invasive vaginal cancer share many of the same risk factors as cervical cancer, such as tobacco use, younger age at coitarche, HPV and multiple sexual partners.^5–7 In fact, higher rates of vaginal cancer are observed in patients with a previous diagnosis of cervical cancer or cervical intraepithelial neoplasia.^7,8As is true for other gynaecologic malignancies, vaginal cancer diagnosis and staging rely primarily on clinical evaluation by the International Federation of Gynecology and Obstetrics (FIGO).⁹ Pelvic examination continues to be the most important tool for evaluating local extent of disease, but this method alone is limited in its ability to detect lymphadenopathy and the extent of tumour infiltration. Hence, FIGO encourages the use of imaging. Fluorine-18 fludeoxyglucose-positron emission tomography (¹⁸F-FDG-PET), a standard imaging tool for staging and follow-up in cervical cancer, can also be used for vaginal tumours, with improved sensitivity for nodal involvement compared to CT alone.¹⁰ In addition to staging for nodal and distant disease, CT [simulation with three dimensional (3D) conformations] is particularly useful for treatment planning and delivery of external beam radiation. MRI, with its excellent soft tissue resolution, is commonly used in gynaecologic malignancies and has been shown to be accurate in diagnosis, local staging and spread of disease in vaginal cancer.^11,12 While no formal studies are available for vaginal cancer, in cervical cancer MRI actually alters the stage in almost 30% of patients.^13–15Treatment planning in primary vaginal cancer is complex and requires a detailed understanding of the extent of disease. Because vaginal cancer is rare, treatment plans remain less well defined, often individualized and extrapolated from institutional experience and outcomes in cervical cancer.^1,16–19 There is an increasing trend towards organ preservation and treatment strategies based on combined external beam radiation and brachytherapy, often with concurrent chemotherapy,^14,20,21 surgery being reserved for those with in situ or very early-stage disease.²² Increasing utilization of MR may provide superior delineation of tumour volume, both for initial staging and follow-up, to allow for better treatment planning.²³     

Value of diffusion-weighted imaging in the detection of viable tumour after neoadjuvant chemoradiation therapy in patients with locally advanced rectal cancer: comparison with T2 weighted and PET/CT imaging

Objectives

To evaluate the added value of diffusion-weighted imaging (DWI) in combination with T₂ weighted imaging (T2WI) compared with T2WI alone or positron emission tomography (PET)/CT for detecting viable tumour after neoadjuvant chemoradiation therapy (CRT) in patients with locally advanced rectal cancer.

Methods

50 consecutive patients with locally advanced rectal cancer (≥T3 or lymph node positive) who underwent neoadjuvant CRT and subsequent surgery were enrolled in this retrospective study. All patients underwent 3.0 T rectal MRI and PET/CT after completing CRT. For qualitative analysis, two radiologists independently reviewed T2WI alone and DWI with T2WI over a 1-month interval. One nuclear medicine physician reviewed PET/CT images using a five-point scale. Diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting viable tumour were assessed. For quantitative analysis, the apparent diffusion coefficients (ADCs) of the lesions were measured and compared between the viable tumour group and non-viable tumour groups.

Results

For detecting viable tumours, DWI with T2WI improved diagnostic accuracies (Reviewer 1 detected 90%; Reviewer 2, 86%) over T2WI alone (Reviewer 1 detected 76%, p=0.5; Reviewer 2, 64%, p=0.013) or PET/CT (48%, p<0.001). The sensitivity of DWI with T2WI (Reviewer 1 detected 98%; Reviewer 2, 91%) was significantly higher than those of T2WI alone (Reviewer 1 detected 77%; Reviewer 2, 64%) or PET-CT (43%, p<0.05). Only for Reviewer 2 was the NPV of DWI with T2WI (43%) significantly different from that of PET/CT (17%, p<0.05). The specificities and PPVs of DWI with T2WI were not improved over those of T2WI alone or of PET/CT (both p>0.05). The mean ADC of the viable tumour group (0.93×10⁻³ mm² sc⁻¹) was significantly lower than that of the non-viable tumour group (1.55×10⁻³ mm² sc⁻¹, p<0.0001).

Conclusion

Adding DWI to T2WI is helpful for detecting viable tumours after neoadjuvant CRT compared with T2WI alone or PET/CT in patients with locally advanced rectal cancer.Neoadjuvant chemoradiation therapy (CRT) has now become the standard of care for clinically staged, locally advanced rectal cancer. This treatment is associated with fewer local recurrences [1] and may also result in improved long-term survival [2]. Post-operative histopathological results are important indicators of prognosis in rectal cancer after CRT [3,4]. Therefore, pre-operative and non-invasive assessment of response to CRT of rectal cancer, and the identification of viable tumours after CRT, are crucial for planning the most beneficial strategies for each individual patient. This could guide the optimisation of the surgical approach, perhaps indicating sphincter-saving surgery in deep-seated tumours or less aggressive resection in initially advanced tumours.Although MRI is considered the most accurate tool for primary tumour staging in rectal cancer [5-7], this modality has intrinsic limitations in the differentiation of residual viable tumour from surrounding fibrosis after neoadjuvant CRT of rectal cancer [8-10]. With the introduction of higher field-strength MR scanners and the parallel imaging technique for rectal MRI, diffusion-weighted imaging (DWI) has been shown to have several potential benefits for the assessment of tumour localisation and staging [11,12]. The usefulness of DWI at 1.5 T in measuring treatment response has been measured in several clinical studies [13-15]. Recently, 3.0 T MR scanners have become commercially available [16-18]; the increase in signal-to-noise ratio (SNR) provided by these machines offers increased DWI quality and improvements to apparent diffusion coefficient (ADC) maps.Aside from innovative MRI approaches such as DWI, non-invasive proof of tumour viability can be obtained using fluorine-18 fludeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/CT. Many investigators have reported a substantial decrease in standardised uptake value (SUV) post-CRT in responders compared with non-responders [19-22]. However, only a few studies have compared the abilities of MRI and PET/CT to enable prediction of responses to neoadjuvant CRT [23,24]. There has been no published comparative study of DWI and PET/CT in the evaluation of tumour viability after neoadjuvant CRT in locally advanced rectal cancer.Thus, the purpose of our study was to evaluate the added value of DWI in combination with T₂ weighted imaging (T2WI) compared with T2WI alone or PET/CT for detecting viable tumour after neoadjuvant CRT in patients with locally advanced rectal cancer.     

Correlation of the apparent diffusion coefficiency values on diffusion-weighted imaging with prognostic factors for breast cancer

Objective

The aim of this study was to correlate the apparent diffusion coefficient (ADC) value of breast cancer with prognostic factors.

Methods

335 patients with invasive ductal carcinoma not otherwise specified (IDC NOS) and ductal carcinoma in situ (DCIS) who underwent breast MRI with diffusion-weighted imaging were included in this study. ADC of breast cancer was calculated using two b factors (0 and 1000 s mm^–2). Mean ADCs of IDC NOS and DCIS were compared and evaluated. Among cases of IDC NOS, mean ADCs were compared with lymph node status, size and immunochemical prognostic factors using Student''s t-test. ADC was also correlated with histological grade using the Kruskal–Wallis test.

Results

Mean ADC of IDC NOS was significantly lower than that of DCIS (p<0.001). However, the mean ADC of histological grade of IDC NOS was not significantly different (p=0.564). Mean ADC of oestrogen receptor (ER)-positive or progesterone receptor (PR)-positive cancer was significantly lower than that of ER-negative or PR-negative cancer (p=0.003 vs p=0.032). Mean ADC of Ki-67 index-positive cancer was significantly lower than that of Ki-67 index-negative cancer (p=0.028). Mean ADC values of cancers with increased microvascular density (MVD) were significantly lower than those of cancer with no MVD increase (p=0.009). No correlations were observed between mean ADC value and human growth factor receptor 2 expression, tumour size and lymph node metastasis.

Conclusion

Low ADC value was correlated with positive expression of ER, PR, increased Ki-67 index, and increased MVD of breast cancer.Breast MRI is an established supplemental technique to mammography and ultrasonography for evaluation of suspicious breast lesions. Diffusion-weighted MRI (DWI) has recently been integrated into the standard breast MRI for discrimination of benign and malignant breast lesions obtained with dynamic contrast-enhanced MRI [1-13]. DWI is a non-invasive technique that represents the biological character of the mainly Brownian movement of protons in bulk water molecules in vivo. Apparent diffusion coefficient (ADC) values are quantified by measurement of mean diffusivity along three orthogonal directions, which are affected by cellularity of the tissue, fluid viscosity, membrane permeability and blood flow [7,9-11]. Microstructural characteristics, including water diffusion and blood microcirculations in capillary networks, were associated with ADC value. Decreased movement of molecules in highly cellular tissue showed correlation with a low ADC value [3,4]. Several studies of DWI of the breast have reported significantly lower ADC values in malignant tumours, compared with benign breast lesions and normal tissue [1-3,5-11,14]. Classic prognostic markers, including tumour size and grade, and lymph node status in patients with breast cancer, and molecular markers, including oestrogen receptor (ER), progesterone receptor (PR), Ki-67 index, human growth factor receptor 2 (HER2) protein and angiogenic molecular markers, have been reported [1,15,16]. Few studies have examined the correlation between ADC values and prognostic factors [1,8]. The purpose of this study is to compare ADC values of DWI of breast cancer with prognostic factors.     

Mammography before post-operative radiotherapy in conservatively managed breast cancer patients: is it useful?

Objective

The aim of this study was to evaluate the role of bilateral mammography undertaken before adjuvant radiotherapy in patients with conservatively managed invasive carcinoma of the breast.

Methods

Patients with invasive breast cancer referred to the Radiotherapy Unit of the Università Cattolica del Sacro Cuore, in Campobasso, Italy, between March 2002 and September 2006 were retrospectively reviewed. Patients were referred to our facility from other local and regional hospitals where they received breast-conserving surgery and adjuvant chemotherapy. They presented to our department for post-operative whole-breast radiotherapy. All patients underwent physical examination and bilateral mammography prior to adjuvant irradiation.

Results

201 patients met the selection criteria as delineated. Of these 201 patients who underwent pre-radiotherapy mammography, 3 had suspicious findings on mammography. In two of those cases, the histopathological examination confirmed the presence of residual disease within the residual mammary gland. In one case, the pre-radiotherapy mammogram allowed for the detection of disease persistence which was not otherwise appreciated on physical exam. In the other case, the diagnostic imaging confirmed only the findings of the physical exam. In both cases of residual disease, the tumour was found elsewhere in the breast and not at the primary site. In one patient, the radiological re-assessment led to a false-positive result. No cases of contralateral synchronous breast cancer were observed. The overall adjunctive cost of this strategy including a routine mammography besides the clinical visit was €7012 for all patients.

Conclusions

No clear recommendation exists regarding post-operative mammography before adjuvant radiotherapy. In our experience, this strategy allowed for the detection of gross disease persistence after surgery which was not appreciated at clinical examination in 1 case out of 201. In this patient, adjuvant radiotherapy up to a total dose of 50 Gy would have been inadequate. Given the low cost of mammography, further investigation about its role in pre-radiotherapy evaluation is warranted.The role of post-operative radiotherapy in preventing local recurrence after breast-conserving surgery for early-stage invasive breast cancer is well established from multiple Phase III clinical trials [1-3]. Despite adjuvant radiotherapy, the cumulative incidence of ipsilateral breast tumour recurrence (IBTR) ranges from 2.2% to 5.2% [2-3]. Although the risk of developing IBTR persists even after 15 years from the initial presentation [1], it is higher during the first 5 years [4], with an incidence of 5–10% [5]. Patients who develop local failure appear to have fewer disease-free intervals and substantially worse overall survival rates [6,7].With whole-breast irradiation, tumour doses of approximately 45–50 Gy are delivered to the entire breast over 3–6 weeks, often followed by a boost to the tumour bed. On a radiobiological basis, the risk of local recurrence after complete surgery is related to the density of clonogenic tumour cells when radiotherapy is initiated. If a residual macroscopic tumour is present, a prophylactic radiation dose is not enough to prevent a local failure; therefore, adjuvant whole-breast radiotherapy is inadequate.The aim of this study was to evaluate whether a mammographic assessment before adjuvant radiotherapy can detect any residual macroscopic tumour within the remaining breast parenchyma in patients who have undergone breast conservation.     

Primary and secondary breast lymphoma: prevalence, clinical signs and radiological features

Objectives

The purpose of this study was to determine the prevalence, clinical signs and radiological features of breast lymphoma.

Methods

This is a retrospective review of 36 patients with breast lymphoma (22 primary and 14 secondary). 35 patients were female and 1 was male; their median age was 65 years (range 24–88 years). In all patients, the diagnosis was confirmed histopathologically.

Results

The prevalence of breast lymphoma was 1.6% of all identified cases with non-Hodgkin lymphoma and 0.5% of cases with breast cancer. B-cell lymphoma was found in 94% and T-cell lymphoma in 6%. 96 lesions were identified (2.7 per patient). The mean size was 15.8±8.3 mm. The number of intramammary lesions was higher in secondary than in primary lymphoma. The size of the identified intramammary lesions was larger in primary than in secondary lymphoma. Clinically, 86% of the patients presented with solitary or multiple breast lumps. In 14%, breast involvement was diagnosed incidentally during staging examinations.

Conclusion

On mammography, intramammary masses were the most commonly seen (27 patients, 82%). Architectural distortion occurred in three patients (9%). In three patients (9%), no abnormalities were found on mammography. On ultrasound, the identified lesions were homogeneously hypoechoic or heterogeneously mixed hypo- to hyperechoic. On MRI, the morphology of the lesions was variable. After intravenous administration of contrast medium, a marked inhomogeneous contrast enhancement was seen in most cases. On CT, most lesions presented as circumscribed round or oval masses with moderate or high enhancement.Ductal and lobular carcinomas are the most frequent tumours of the breast. Breast involvement by lymphoma is very rare. It can occur as a primary breast tumour or as an extranodal manifestation in systemic disease [1-5]. According to the literature, the prevalence of breast lymphoma (BL) ranges from 0.04 to 0.5% of malignant breast neoplasms [1,2]. In addition, the prevalence of primary BL (PBL) varies from 0.85 to 2.2% of extranodal malignant lymphomas [3-5]. Secondary BL (SBL) is more common [6-8]. The rarity of BL can be attributed to the fact that the breast contains very little lymphoid tissue [9,10].Only a few of the published studies focus on the radiological features of BL, and conflicting findings of BL have been reported [1,7,11-13]. Only in one investigation has the distinction between primary and secondary breast involvement been taken into consideration [1]. Therefore, the aim of this study was to determine the prevalence of BL in our population and to analyse its clinical and radiological characteristics.     

Towards clinical assessment of velopharyngeal closure using MRI: evaluation of real-time MRI sequences at 1.5 and 3 T

Objective

The objective of this study was to demonstrate soft palate MRI at 1.5 and 3 T with high temporal resolution on clinical scanners.

Methods

Six volunteers were imaged while speaking, using both four real-time steady-state free-precession (SSFP) sequences at 3 T and four balanced SSFP (bSSFP) at 1.5 T. Temporal resolution was 9–20 frames s⁻¹ (fps), spatial resolution 1.6×1.6×10.0–2.7×2.7×10.0 mm³. Simultaneous audio was recorded. Signal-to-noise ratio (SNR), palate thickness and image quality score (1–4, non-diagnostic–excellent) were evaluated.

Results

SNR was higher at 3 T than 1.5 T in the relaxed palate (nasal breathing position) and reduced in the elevated palate at 3 T, but not 1.5 T. Image quality was not significantly different between field strengths or sequences (p=NS). At 3 T, 40% acquisitions scored 2 and 56% scored 3. Most 1.5 T acquisitions scored 1 (19%) or 4 (46%). Image quality was more dependent on subject or field than sequence. SNR in static images was highest with 1.9×1.9×10.0 mm³ resolution (10 fps) and measured palate thickness was similar (p=NS) to that at the highest resolution (1.6×1.6×10.0 mm³). SNR in intensity–time plots through the soft palate was highest with 2.7×2.7×10.0 mm³ resolution (20 fps).

Conclusions

At 3 T, SSFP images are of a reliable quality, but 1.5 T bSSFP images are often better. For geometric measurements, temporal should be traded for spatial resolution (1.9×1.9×10.0 mm³, 10 fps). For assessment of motion, temporal should be prioritised over spatial resolution (2.7×2.7×10.0 mm³, 20 fps).

Advances in knowledge

Diagnostic quality real-time soft palate MRI is possible using clinical scanners and optimised protocols have been developed. 3 T SSFP imaging is reliable, but 1.5 T bSSFP often produces better images.Approximately 450 babies born in the UK every year have an orofacial cleft [1], the majority of which include the palate [2]. While a cleft palate is commonly repaired surgically at around 6 months [3], residual velopharyngeal insufficiencies require follow-up surgery in 15–50% of cases [4]. This residual defect results in an incomplete closure of the velopharyngeal port, which in turns leads to hypernasal speech. Assessment of velopharyngeal closure in speech therapy is commonly performed using X-ray videofluoroscopy or nasendoscopy [5,6]. While nasendoscopy is only minimally invasive, it may be uncomfortable and provides only an en face view of the velopharyngeal port. In contrast, X-ray videofluoroscopy is non-invasive and produces an image which is a projection of the target anatomy. Additional information may be obtained from projections at multiple angles [5,7], but anatomical structures may overlie each other. Furthermore, soft tissue contrast, such as that from the soft palate, is poor, although it may be improved using a barium contrast agent coating [8] at the expense of making the procedure more invasive and unpleasant. Arguably the greatest drawback of X-ray videofluoroscopy is the associated ionising radiation dose, which carries increased risk in paediatric patients [9].An increasing number of research studies have used MRI to image the soft palate [10-13] and upper vocal tract [14-17]. In contrast to X-ray videofluoroscopy and nasendoscopy, MRI provides tomographic images in any plane with flexible tissue contrast. As a result, MRI has been used to obtain images of the musculature of the palate at rest and during sustained phonation [10,18,19]. It has also been used to image the whole vocal tract at rest or during sustained phonation [20-27] and with a single mid-sagittal image dynamically during speech [13,15-17,28-35].For assessment of velopharyngeal closure, dynamic imaging with sufficient temporal resolution and simultaneous audio recording is required. Audio recording during imaging is complicated by the loud noise of the MRI scanner, and both the safety risk and image degradation caused by using an electronic microphone within the magnet. As a result, optical fibre-based equipment with noise cancellation algorithms must be used [36].In order to fully resolve soft palate motion, Narayanan et al [30] suggested that a minimum temporal resolution of 20 frames s⁻¹ (fps) is required. A similar conclusion was reached by Bae et al [13], based on measurements of soft palate motion extracted from X-ray videofluoroscopy. Using segmented MRI, Inoue et al [35] demonstrated that changes in the velar position that were evident at acquired frame rates of 33 fps were not observed at 8 fps. However, MRI is traditionally seen as a slow imaging modality and achieving sufficient temporal resolution at an acceptable spatial resolution is challenging. Furthermore, as the soft palate is bordered on both sides by air, the associated changes in magnetic susceptibility at the interfaces make images prone to related artefacts.Dynamic MRI of the vocal tract has been performed using both segmented [17,33,37] and real-time acquisitions [13,15,16,28,31,38]. Segmented acquisitions [39] acquire only a fraction of the k-space data required for each image during one repetition of the test phrase and, hence, require multiple identical repetitions. While these segmented techniques permit high temporal and spatial resolutions [35], they require reproducible production of the same phrase up to 256 times [34], leading to subject fatigue. Differences between repeats of up to 95 ms in the onset of speech following a trigger have also been demonstrated [36].In contrast to segmented techniques, real-time dynamic methods permit imaging of natural speech, but require extremely rapid acquisition and often advanced reconstruction methods. The turbo spin echo (TSE) zoom technique [40] has been used to perform real-time MRI of the vocal tract [29,31] and is available as a clinical tool. The zoom technique excites a reduced field of view in the phase encode direction, hence allowing a smaller acquisition matrix and shorter scan for a constant spatial resolution. While such spin echo-based techniques are less susceptible to magnetic field inhomogeneity related signal dropout artefacts than other sequences, the frame rates achieved with these sequences are limited to 6 fps [31]. Gradient echo-based techniques have also been used to achieve similar temporal resolution [12,41,42] in the upper vocal tract, but are often used at much higher frame rates in other MRI applications such as cardiac imaging [43,44]. A number of gradient echo sequence variants exist. Fast low-angle shot (FLASH) type sequences [45] spoil any remaining transverse magnetisation at the end of every sequence repetition (TR). In contrast, steady-state free-precession (SSFP) sequences are not spoiled [46] and the remaining transverse magnetisation is used in the next TR to improve the signal-to-noise ratio (SNR), but renders the images sensitive to signal loss in the presence of motion. Balanced SSFP (bSSFP) sequences include additional gradients to bring the transverse magnetisation completely back into phase at the end of every TR [47,48]. The result is that bSSFP sequences have high SNR and are less sensitive to motion than SSFP sequences, but are more sensitive to field inhomogeneities, which cause bands of signal dropout.Both TSE and the gradient echo techniques discussed here sample in a rectilinear or Cartesian fashion, where one line of k-space is sampled in each echo. However, for real-time speech imaging, the highest acquired frame rates have been achieved by sampling k-space along a spiral trajectory [15,16,30,49]. While spiral imaging is an efficient way to sample k-space and is motion-resilient, it is prone to artefacts, particularly blurring caused by magnetic field inhomogeneities and off-resonance protons (i.e. fat) [50]. Recently, one group successfully used spiral imaging with multiple saturation bands and an alternating echo time (TE) to achieve an acquired real-time frame rate of 22 fps [13,16]. The saturation bands were used to allow a small field of view to be imaged without aliasing artefacts. The alternating TE was used to generate dynamic field maps which were incorporated into the reconstruction to compensate for magnetic field inhomogeneities. However, such advanced acquisition and reconstruction techniques are only available in a small number of research centres.The aim of this work is to optimise and demonstrate high-temporal-resolution real-time sequences available on routine clinical MRI scanners for assessment of soft palate motion and velopharyngeal closure. Consequently, radial and spiral acquisitions were excluded and the work focuses on Cartesian gradient echo sequences with parallel imaging techniques. As more clinical MRI departments now have 3 T scanners, imaging was performed at both 1.5 and 3 T to enable comparisons. At each field strength, we optimised sequences and implemented four combinations of spatial and temporal resolution in six subjects with simultaneous audio recordings.     

Characterisation of breast papillary neoplasm on automated breast ultrasound

Intraductal papillary neoplasms of the breast form a wide spectrum of pathological changes with benign intraductal papilloma and papillary carcinoma. They can occur anywhere within the breast ductal system. This review illustrates some characteristic appearances of breast papillary neoplasms on coronal planes reconstructed by automatic breast volume scan. Such manifestations are not uncommon in papillary neoplasms, and familiarity will enable confident diagnosis.Papillary lesions of the breast are a heterogeneous group of breast lesions, including intraductal papilloma, atypical papilloma and intraductal papillary carcinoma [1,2]. Although the management of intraductal papillomas is varied, surgical excision is generally recommended as a precaution against the risk of a subsequent carcinoma [3,4]. Recently, some studies have suggested that patients with a tumour measuring <1.5 cm and an ultrasound Breast Imaging—Reporting and Data System (BI-RADS) category of 3 or 4a can be potentially selected for vacuum-assisted biopsy, but only if the tumour does not extend into the branching ducts [5,6]. Ueng et al [2] recommended that localised papillary lesions should be excised completely with a small rim of uninvolved breast tissue without any prior needle instrumentation if and when the papillary nature can be determined by imaging. Therefore, a careful imaging evaluation is necessary because it could help to identify the papillary neoplasm nature and select the high-risk lesions for proper treatment.Ultrasound has a greater sensitivity for detecting all papillary lesions than mammography [7]. Recently, automated breast ultrasound scanners have been developed, and the ultrasound volume data set of the whole breast can be acquired in a standard manner [8]. They have already shown potential for characterisation of breast tumours [9,10]. However, these studies did not detail the ultrasound features of intraductal papillary neoplasms on automated breast ultrasound. The reconstructed coronal views are also expected to provide more information and thus help to differentiate these lesions from other focal breast abnormalities.     

A change in the apparent diffusion coefficient after treatment with bevacizumab is associated with decreased survival in patients with recurrent glioblastoma multiforme

Objectives

The aim of this study was to determine the prognostic significance of changes in parameters derived from diffusion tensor imaging (DTI) that occur in response to treatment with bevacizumab and irinotecan in patients with recurrent glioblastoma multiforme.

Methods

15 patients with recurrent glioblastoma multiforme underwent serial 1.5 T MRI. Axial single-shot echo planar DTI was obtained on scans performed 3 days and 1 day prior to and 6 weeks after initiation of therapy with bevacizumab and irinotecan. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were registered to whole brain contrast-enhanced three-dimensional (3D) spoiled gradient recalled and 3D fluid attenuation inversion recovery (FLAIR) image volumes. Anatomic image volumes were segmented to isolate regions of interest defined by tumour-related enhancement (TRE) and FLAIR signal abnormality (FSA). Mean ADC and mean FA were calculated for each region. A Bland–Altman repeatability coefficient was also calculated for each parameter based on the two pre-treatment studies. A patient was considered to have a change in FA or ADC after therapy if the difference between the pre- and post-treatment values was greater than the repeatability coefficient for that parameter. Survival was compared using a Cox proportional hazard model.

Results

DTI detected a change in ADC within FSA after therapy in nine patients (five in whom ADC was increased; four in whom it was decreased). Patients with a change in ADC within FSA had significantly shorter overall survival (p=0.032) and progression free survival (p=0.046) than those with no change.

Conclusion

In patients with recurrent glioblastoma multiforme treated with bevacizumab and irinotecan, a change in ADC after therapy in FSA is associated with decreased survival.Genotypic heterogeneity within histologically indistinguishable tumours remains a major barrier to successful treatment of patients with high-grade primary brain tumours [1]. Because of this heterogeneity, only a minority of individual tumours are likely to respond to any given chemotherapeutic agent [2]. Early identification of non-responders would allow potentially more effective therapy to be instituted while minimising the morbidity and financial cost associated with prolonged, ineffective treatment. Current assessment of therapeutic efficacy relies on changes in cross-sectional area estimated weeks to months after the completion of a treatment protocol [3,4]. Unfortunately, patients with aggressive tumours may experience significant disease progression with related morbidity and mortality before therapy can be evaluated and altered using this approach. Biomarkers of treatment response that are independent of late changes in tumour volume will be crucial for optimal treatment of this patient group.Diffusion-weighted MRI (DWI) can be used to characterise early tissue microstructural changes associated with cell death [4,5]. Since parameters derived from DWI can provide a quantitative assessment of such effects, there is increasing interest in this technique as a biomarker of therapeutic efficacy. Although there is good evidence that DWI can be used to characterise treatment effects, the optimal parameter and region of interest are yet to be determined [4,6-12].The preponderance of studies on this subject has quantified the apparent diffusion coefficient (ADC) within regions of interest defined by abnormal tumour-related enhancement [6,9,11]. In vivo, the ADC is primarily determined by cell density [4,8,13,14]. As a result, changes in the ADC are sensitive to early alterations in tissue microstructure related to cell death; these changes include cell swelling and loss of membrane integrity associated with early necrosis as well as cell shrinkage due to apoptosis [11,15]. Indeed, it has been demonstrated that changes in the ADC within enhancing regions of interest can be used to identify the response to chemotherapy earlier than standard MRI [9]. Recent evidence, however, suggests the importance of non-enhancing, infiltrative tumour, as defined on fluid attenuation inversion recovery (FLAIR) images, with respect to tumour progression [16,17]. This non-enhancing component of tumour seems to be of particular relevance to patients treated with anti-angiogenesis agents [16,17]. Since the ADC is sensitive to variations in vasogenic oedema (increasing oedema tends to decrease cell density), in addition to the aforementioned direct effects on tumour cells, we hypothesise that the ADC would be an ideal parameter to characterise the effects of treatment within regions of interest defined by abnormal tumour-related FLAIR signals.Although there are few data in patients with brain tumours, there is some evidence that parameters of diffusion anisotropy derived from diffusion tensor imaging (DTI) may more accurately depict early changes in brain tissue microstructure than the ADC in central nervous system (CNS) diseases [18]. Fractional anisotropy (FA) is a measure of the degree of directional variation of the diffusion of water protons. Like the ADC, FA has been shown to correlate with cell density [7,18,19], but FA provides additional information regarding the integrity and alignment of parenchymal fibre tracts [20]. A recent study in patients with primary brain tumours demonstrated increasing FA across the study population within regions of interest defined by tumour-related contrast enhancement as early as 1 day after initiation of chemotherapy [12]. This same study failed to detect a significant change in the ADC at the same time point, raising the possibility that FA may be a more sensitive parameter to early treatment response.Although these preliminary results are promising, the significance of such changes with respect to patient survival has not been widely studied. In addition, there are very few data regarding the test–retest reproducibility of these parameters in patients with primary brain tumours, information which is crucial for understanding whether changes in these parameters can be used to guide therapy. In particular, an understanding of the magnitude of variability intrinsic to the method will be required to ascribe significance to changes in these parameters that occur after therapy in an individual patient.The goal of this study is to use the repeatability of ADC and FA derived from DTI to devise a method by which prognostic significance can be assigned to changes in these parameters that occur after therapy in patients with glioblastoma multiforme. In particular, we prospectively identified the following two null hypotheses:

• Patients with an increase in FA within regions of interest defined by tumour-related enhancement will not survive longer than those with no change or a decrease in FA.
• Patients with a change in ADC within regions of interest defined by an abnormal FLAIR signal will not survive longer than those with no change.

Although it may seem counterintuitive to evaluate the significance of any change in the ADC without respect for direction, there is evidence that both increasing and decreasing the ADC may reflect a clinically relevant treatment response [9,11].     

Prognostic factors associated with a subchondral insufficiency fracture of the femoral head

Objective

The aim of this study was to identify the risk factors associated with the prognosis of a subchondral insufficiency fracture of the femoral head (SIF).

Methods

Between June 2002 and July 2009, 25 patients diagnosed with SIF were included in this study. Sequential radiographs were evaluated for the progression of collapse. Clinical profiles, including age, body mass index, follow-up period and Singh’s index, were documented. The morphological characteristics of the low-intensity band on T₁ weighted MRI were also examined with regards to four factors: band length, band thickness, the length of the weight-bearing portion and the band length ratio (defined as the proportion of the band length to the weight-bearing portion of the femoral head in the slice through the femoral head centre).

Results

Radiographically, a progression of collapse was observed in 15 of 25 (60.0%) patients. The band length in patients with progression of collapse [22.5 mm; 95% confidence interval (CI) 17.7, 27.3] was significantly larger than in patients without a progression of collapse (13.4 mm; 95% CI 7.6, 19.3; p<0.05). The band length ratio in patients with progression of collapse (59.8%; 95% CI 50.8, 68.9) was also significantly higher than in patients without a progression of collapse (40.9%; 95% CI 29.8, 52.0; p<0.05). No significant differences were present in the other values.

Conclusion

These results indicate that the band length and the band length ratio might be predictive for the progression of collapse in SIF.Subchondral insufficiency fractures of the femoral head (SIF) often occur in osteoporotic elderly patients [1-9]. Patients usually suffer from acute hip pain without any obvious antecedent trauma. Radiologically, a subchondral fracture is seen primarily in the superolateral portion of the femoral head [4,5,10]. T₁ weighted MRI reveal a very low-intensity band in the subchondral area of the femoral head, which tends to be irregular, disconnected and convex to the articular surface [2,4,5,7,9,11]. This low-intensity band in SIF was histologically proven to correspond with the fracture line and associated repair tissue [5,9]. Some cases of SIF resolve after conservative treatment [5,11-14]; other cases progress until collapse, thereby requiring surgical treatment [4-10,15]. The prognosis of SIF patients remains unclear.The current study investigated the risk factors that influence the prognosis of SIF based on the progression to collapse.     

Semi-automated and automated glioma grading using dynamic susceptibility-weighted contrast-enhanced perfusion MRI relative cerebral blood volume measurements

Objective

Despite the established role of MRI in the diagnosis of brain tumours, histopathological assessment remains the clinically used technique, especially for the glioma group. Relative cerebral blood volume (rCBV) is a dynamic susceptibility-weighted contrast-enhanced perfusion MRI parameter that has been shown to correlate to tumour grade, but assessment requires a specialist and is time consuming. We developed analysis software to determine glioma gradings from perfusion rCBV scans in a manner that is quick, easy and does not require a specialist operator.

Methods

MRI perfusion data from 47 patients with different histopathological grades of glioma were analysed with custom-designed software. Semi-automated analysis was performed with a specialist and non-specialist operator separately determining the maximum rCBV value corresponding to the tumour. Automated histogram analysis was performed by calculating the mean, standard deviation, median, mode, skewness and kurtosis of rCBV values. All values were compared with the histopathologically assessed tumour grade.

Results

A strong correlation between specialist and non-specialist observer measurements was found. Significantly different values were obtained between tumour grades using both semi-automated and automated techniques, consistent with previous results. The raw (unnormalised) data single-pixel maximum rCBV semi-automated analysis value had the strongest correlation with glioma grade. Standard deviation of the raw data had the strongest correlation of the automated analysis.

Conclusion

Semi-automated calculation of raw maximum rCBV value was the best indicator of tumour grade and does not require a specialist operator.

Advances in knowledge

Both semi-automated and automated MRI perfusion techniques provide viable non-invasive alternatives to biopsy for glioma tumour grading.MRI is an important tool for the diagnosis of brain tumours; however, despite its established role, histopathological assessment forms the basis of prognosis calculation and treatment planning in most cases, especially for the glioma group [1-6]. Recently developed radiology-based techniques have been utilised to accurately grade intra-axial tumours, avoiding the need for time-consuming and invasive histopathological examination. These techniques include dynamic susceptibility-weighted contrast-enhanced perfusion MRI parameters such as cerebral blood flow [7-10], and metabolic measurements such as the choline–creatine ratio [11], as well as relative cerebral blood volume (rCBV) [12-17].One of the most promising and least intrusive of these new techniques uses rCBV measurements following intravenous contrast injection. rCBV is expected to correlate with tumour grade as it has been correlated with vascular endothelial growth factor expression and thus probable angiogenic ability [18]. Two main techniques have been used to measure rCBV in tumours: region of interest (ROI) analysis and histogram analysis. In ROI analyses, small ROIs are chosen by experienced radiologists in areas representing the maximum perfusion of the tumour, while avoiding artefacts such as large vessels. Good correlation with tumour grade has been observed [12,13], and this technique can also help differentiate oligodendroglioma from astrocytoma [14,15]. Histogram analyses similarly utilise experienced radiologists to draw a large analytical region around the tumour margins. All pixels contained within it are analysed to calculate various statistical values, which have also been shown to correlate with tumour grade [16,17,19,20].The primary limitation of a ROI analysis is the labour-intensive nature of finding the maximum rCBV value (rCBV_max) in the ROI and differentiating this from a possible vessel-perfusion effect, which requires the skills of a specialist. For a histogram analysis, vessel perfusion skews results, as has been shown in a recent study in which vessels were either included or excluded during ROI placement [21].We have developed easy-to-use analysis software capable of both semi-automated and automated glioma grading using ROI and histogram analyses based on perfusion scans. Our program is designed to enable non-specialists to perform the analysis, removing the need for a neuroradiologist operator, and to avoid the skewing effect of tumour vessels. The correlation of tumour parameters, calculated with the software, to glioma grade is determined using patient data previously classified from histology.     

MRI features of serous oligocystic adenoma of the pancreas: differentiation from mucinous cystic neoplasm of the pancreas

Objectives

The purpose of this study was to describe the MRI features of the benign pancreatic neoplasm serous oligocystic adenoma (SOA) that differ from those of mucinous cystic neoplasm (MCN), a neoplasm with the potential for malignant degeneration.

Methods

Seven patients with SOA (seven women; mean age 36.6 years) and eight patients with MCN (eight women: mean age 39.9 years) were included. Several imaging features were reviewed: mass size, location, shape, wall thickness, cyst configuration (Type I, unilocular; Type II, multiple clustered cyst; Type III, cyst with internal septation) and signal intensity of the lesion with heterogeneity.

Results

SOA lesions were smaller (3.4 cm) than those of MCN (9.3 cm) (p=0.023). The commonest lesion shape was lobulated (85.7%) for SOA, but oval (50.0%) or lobulated (37.5%) for MCN (p=0.015). The most common cyst configuration was Type II (85.7%) for SOA and Type III (75.0%) for MCN (p=0.008). Heterogeneity of each locule in T₁ weighted images was visible in all cases of MCN, but in no case for SOA (p=0.004).

Conclusion

SOA could be differentiated from MCN by identifying the imaging features of lobulated contour with multiple clustered cyst configurations and homogeneity of each locule in T₁ weighted MR images.Serous oligocystic adenoma (SOA) is a recently described rare, benign pancreatic neoplasm and a morphological variant of serous microcystic adenoma, because it contains six or fewer cysts and the cysts are large (>2 cm) [1,2]. Pathologically, SOA is a benign pancreatic neoplasm composed of a few relatively large cysts uniformly lined with glycogen-rich cuboidal epithelial cells [3]. According to the World Health Organization classification, SOA is a subgroup of pancreatic serous cystic tumours and the term SOA is a synonym for macrocystic serous cystadenoma [3,4].The CT and MRI features of SOA of the pancreas are documented [2]. On CT and MRI, SOA typically appears as a small unilocular or bilocular cyst (<5 cm) with a thin wall (<2 mm) that lacks mural nodules or calcifications [2]. Because the cystic spaces are >2 cm, SOA images can be mistaken for mucinous cystic neoplasm (MCN), pseudocyst or intraductal papillary mucinous tumour [2,5-7]. It is very difficult to differentiate SOA from MCN by clinical and radiological features [2,6,8,9]. SOA does not require resection unless it causes symptoms, but MCN should be resected because of a potential for malignant degeneration [5,7,8]. Endoscopic ultrasound and cyst fluid aspiration have a role in distinguishing mucinous and serous lesions, but it is an invasive procedure with a risk of complications such as pancreatitis [10]. Therefore, it is clinically valuable to determine characteristic imaging findings that can distinguish SOA from MCN.Recently, Kim et al [6] and Cohen-Scali et al [5] described characteristic CT findings that can be used to differentiate SOA from MCN. MRI can demonstrate septa within a lesion with greater sensitivity than CT; therefore, MRI provides a better evaluation of tissue characteristics than CT [1,11]. However, few studies have described the MRI features of SOA [1,2]. The purpose of this study was to describe the differences in the MRI features of SOA and MCN in the pancreas.     

Diagnostic quality of 50 and 100 μm computed radiography compared with screen-film mammography in operative breast specimens

Objective

To compare reader ratings of the clinical diagnostic quality of 50 and 100 μm computed radiography (CR) systems with screen–film mammography (SFM) in operative specimens.

Methods

Mammograms of 57 fresh operative breast specimens were analysed by 10 readers. Exposures were made with identical position and compression with three mammographic systems (Fuji 100CR, 50CR and SFM). Images were anonymised and readers blinded to the CR system used. A five-point comparative scoring system (−2 to +2) was used to assess seven quality criteria and overall diagnostic value. Statistical analysis was subsequently performed of reader ratings (n=16 925).

Results

For most quality criteria, both CR systems were rated as equivalent to or better than SFM. The CR systems were significantly better at demonstrating skin edge and background tissue (p<1×10⁻⁵). Microcalcification was best demonstrated on the CR50 system (p<1×10⁻⁵). The overall diagnostic value of both CR systems was rated as being as good as or better than SFM (p<1×10⁻⁵).

Conclusion

In this clinical setting, the overall diagnostic performance of both CR systems was as good as or better than SFM, with the CR50 system performing better than the CR100.There are currently three technologies widely available for diagnostic mammography: screen–film mammography (SFM) and two forms of large-field digital mammography [1]. The use of the term full-field digital mammography (FFDM) varies in the published literature and has been applied to both computed radiography (CR) and direct digital radiography (DR). Small-field digital mammography (SFDM) is mainly used for imaging during stereotactic biopsy [2].The advantages of digital mammography over SFM include: improved sensitivity in dense breast tissue, reduced radiation dose, the ability to manipulate images for review, and digital storage and retrieval methods [3]. CR was the earliest digital system in use. Imaging cassettes contain a re-useable photostimulable phosphor, replacing the traditional screen–film cassettes, and are then transferred to a laser reader. DR has an in-built detector and reader. Digital mammography has a lower spatial resolution than SFM, but has a very high contrast resolution. This allows the overall resolution of digital mammography to be at least equivalent to SFM [4-8], even when viewing calcification smaller than the pixel size [9]. Some CR systems have not met the quality standards of a number of governing bodies for mammography, including the European Network of Reference Assessment Centres (EUREF) and the NHS Breast Screening Programme (NHSBSP) [10,11]. This is related to the resolution achievable with 100 µm cassettes [12]. It is now known that CR systems using 50 µm cassettes can provide improved resolution, at an acceptable mean glandular dose, and have been approved for screening by the NHSBSP [13-15].Phantom studies indicate that the resolution and performance of DR are greater than those of CR [16,17], but have limitations. Although there are many clinical studies comparing the performance of DR and SFM [4-7,9,18-26], there are fewer that compare CR with SFM or DR [8,25,27-32]. We sought a method to compare the clinical diagnostic quality of two types of CR technology with that of SFM. We chose to study surgical specimens of breast tissue, which, although not absolutely comparable to in vivo mammography, allows realistic testing of image quality. In addition, multiple exposures can be obtained in reproducible conditions without irradiating the patient.     

The intravertebral cleft in benign vertebral compression fracture: the diagnostic performance of non-enhanced MRI and fat-suppressed contrast-enhanced MRI

We compared the diagnostic performance of non-enhanced MRI and fat-suppressed contrast-enhanced MRI (CEMRI) in diagnosing intravertebral clefts in benign vertebral compression fractures (VCFs). We retrospectively reviewed 99 consecutive patients who had undergone percutaneous vertebroplasty for VCFs. A cleft was defined as a signal void or hyperintense area on non-enhanced MRI (T₁ and T₂ weighted imaging) or as a hypointense area within a diffusely enhanced vertebra on CEMRI. A cleft was confirmed as a solid opacification on post-procedural radiographs. The interobserver reliability and MRI diagnostic performance were evaluated. The interobserver reliability of non-enhanced MRI was substantial (k _ 0.698) and the interobserver reliability of CEMRI was almost perfect (k _ 0.836). Post-procedural radiographs showed solid cleft opacification in 32 out of the 99 cases. The sensitivity and specificity of non-enhanced MRI were 0.72 and 0.82 (observer 1) and 0.63 and 0.87 (observer 2), respectively. The sensitivity and specificity of CEMRI were 0.94 and 0.63 (observer 1) and 0.85 and 0.60 (observer 2), respectively. The sensitivity of CEMRI was significantly higher than that of non-enhanced MRI, and the specificity of non-enhanced MRI was higher than that of CEMRI. CEMRI was highly reliable and sensitive, and non-enhanced MRI was specific for intravertebral clefts. Therefore, spine MRIs, including CEMRI, could provide useful information about intravertebral clefts before percutaneous vertebroplasty.Intravertebral clefts associated with vertebral compression fractures (VCFs) are radiographic signs representing cavities within fractured vertebrae and have long been considered pathognomonic for avascular necrosis of the spine (Kümmell’s sign) [1–3]. However, several investigators have observed that intravertebral clefts are common in patients with osteoporotic compression fractures [4–6]. Currently, clefts are thought to represent corticocancellous disruption in mobile osteoporotic fractures, rather than avascular necrotic disease [4, 6].Percutaneous vertebroplasty (PV) is an effective and minimally invasive procedure for the treatment of osteoporotic compression fractures [7, 8]. The advent of PV as the major treatment option for VCFs has prompted interest in intravertebral clefts occurring in benign VCFs. Recent studies have suggested that the clinical outcomes and complications associated with PV are influenced by the presence of clefts [4, 9–13]. Thus, radiological detection of clefts is indispensable for managing patients with VCFs.Spine MRI is commonly used for the evaluation of acute VCFs. MRI is useful in distinguishing malignancy from acute osteoporotic VCFs [14, 15] and is effective in demonstrating bone marrow oedema associated with acute compression fractures, which is one of the indications for performing PV [14, 16]. The MRI findings associated with intravertebral clefts have been well described [3–5]. However, there is controversy concerning the efficacy of MRI in diagnosing clefts. Specifically, the reliability and effectiveness of contrast-enhanced MRI (CEMRI), first assessed by Oka et al in 2005 [11], has not been properly evaluated. Such evaluation is important, given that CEMRI entails additional expense.To evaluate the efficacy of the CEMRI for the prediction of intravertebral clefts, we assessed the interobserver reliability and diagnostic performance of non-enhanced T₁ weighted and T₂ weighted MRI (T1WI and T2WI) and CEMRI in the identification of intravertebral clefts in VCFs. We then compared the diagnostic performance of CEMRI with that of non-enhanced MRI.     

Vascular invasion in hepatocellular carcinoma: is there a correlation with MRI?

Objective

Hepatocellular carcinoma (HCC) is one of the commonest malignancies worldwide. Prognosis is predicted by size at diagnosis, vascular invasion and tumour proliferation markers. This study investigates if MRI features of histologically proven HCCs correlate with vascular invasion.

Methods

Between 2006 and 2008, 18 consecutive patients, with a total of 27 HCCs, had comprehensive MRI studies performed at our institution within a median of 36 days of histology sampling. Each lesion was evaluated independently on MRI by 3 radiologists (blinded to both the radiology and histopathology reports) using a 5-point confidence scale for 23 specific imaging features. The mean of the rating scores across readers was calculated to determine interobserver consistency. The most consistent features were then used to examine the value of features in predicting vascular invasion, using a χ² test for trend, having eliminated those features without sufficient variability.

Results

22 of the 23 imaging features showed sufficient variability across lesions. None of these significantly correlated with the presence of vascular invasion, although a trend was identified with the presence of washout in the portal venous phase on MRI and the median size of lesions, which was greater with vascular invasion.

Conclusion

This study suggests that no single MRI feature accurately predicts the presence of vascular invasion in HCCs, although a trend was seen with the presence of washout in the portal venous phase post gadolinium. Larger prospective studies are required to investigate this further.Hepatocellular carcinoma (HCC) is one of the commonest malignancies worldwide, either arising de novo or on a background of cirrhosis. The incidence in Western countries is rising owing to increasing rates of alcoholic liver disease and hepatitis C infection. Untreated, the 5-year survival rate for symptomatic HCC is less than 5% [1]. At present, surgery is the only potentially curative treatment for HCC with options including either a partial hepatectomy or orthotopic liver transplantation (OLT). Following resection there is a 5-year survival rate of 40–50% [2] with a cumulative 5-year recurrence rate between 75 and 100% [3]. The 5-year survival rate in patients with cirrhosis following transplantation of small (<2 cm) HCC is up to 80% [4]. However, the use of OLT is limited owing to the lack of donor livers. Regional therapies such as transcatheter arterial chemoembolisation [5] and percutaneous radiofrequency ablation [6] may improve prognosis. The value of neo-adjuvant and adjuvant chemotherapy and immunotherapy in prolonging survival remains controversial [7,8]. However, a recent study evaluating sorafenib, a multikinase inhibitor, in patients with advanced HCC has shown an increased median overall survival of 2.8 months over a placebo [9].Studies of patients with explanted liver for end-stage cirrhosis have shown that MRI, with the use of dynamic gadolinium-enhanced sequences, has a moderate sensitivity for the detection of HCC of between 55 and 91% [10-12] and specificity between 55 and 86% [11-13]. The sensitivity is lower with lesions <2 cm in size [11-13]. In patients with cirrhosis, HCC is thought to develop as part of a spectrum of de-differentiation from regenerative nodule through to low-grade dysplastic nodule, high-grade dysplastic nodule, then to frankly malignant. Early diagnosis using non-invasive imaging leads to an improved prognosis but at present, unless biopsy is performed, only lesion size is used to determine patient management in those where gross vascular involvement or metastatic spread precludes curative treatment.Several factors predicting outcome have been identified including tumour pathological factors (such as size, stage, grade, the presence of vascular invasion, portal vein tumour thrombus and intrahepatic metastases) [14,15], the patient’s hepatitis status, the patient’s functional liver reserve [16] and the serum α-fetoprotein level [17]. Overall, one of the most strongly correlated factors is the presence or absence of vascular invasion. There is a 4.4- and 15-fold increased risk of recurrence following OLT for HCC in patients with micro- or macrovascular invasion, respectively [18].The aims of this retrospective study were twofold. First to identify the interobserver variability of MRI features for patients with histologically proven HCC, and second to determine if there was a correlation between imaging features on MRI and histologically defined vascular invasion; these MRI features could then serve as a surrogate marker of prognosis. There has been little literature to date attempting to correlate MRI features with microvascular invasion.     

An evaluation of four CT-MRI co-registration techniques for radiotherapy treatment planning of prone rectal cancer patients

Objectives

MRI is the preferred staging modality for rectal carcinoma patients. This work assesses the CT–MRI co-registration accuracy of four commercial rigid-body techniques for external beam radiotherapy treatment planning for patients treated in the prone position without fiducial markers.

Methods

17 patients with biopsy-proven rectal carcinoma were scanned with CT and MRI in the prone position without the use of fiducial markers. A reference co-registration was performed by consensus of a radiologist and two physicists. This was compared with two automated and two manual techniques on two separate treatment planning systems. Accuracy and reproducibility were analysed using a measure of target registration error (TRE) that was based on the average distance of the mis-registration between vertices of the clinically relevant gross tumour volume as delineated on the CT image.

Results

An automated technique achieved the greatest accuracy, with a TRE of 2.3 mm. Both automated techniques demonstrated perfect reproducibility and were significantly faster than their manual counterparts. There was a significant difference in TRE between registrations performed on the two planning systems, but there were no significant differences between the manual and automated techniques.

Conclusion

For patients with rectal cancer, MRI acquired in the prone treatment position without fiducial markers can be accurately registered with planning CT. An automated registration technique offered a fast and accurate solution with associated uncertainties within acceptable treatment planning limits.Randomised trials have demonstrated that adjuvant radiotherapy (RT) in patients with resectable rectal cancer offers a statistically significant reduction in the risk of local recurrence compared with surgery alone [1]. Two meta-analyses and a systematic review have confirmed this finding [2-4]: cancer-specific survival was found to be improved when RT was delivered with biological equivalent doses of >30 Gy pre-operatively. Two further trials have confirmed similar benefit when short-course pre-operative RT was combined with total mesorectal excision (TME) [5,6].Three further randomised trials have evaluated the role of pre-operative adjuvant chemoradiotherapy (CRT) for patients with stage T3–T4 or node-positive disease. Two of these studies demonstrated a reduction in local recurrence when pre-operative adjuvant CRT was used rather than long-course adjuvant RT alone [7,8]. The third study demonstrated both reduced local recurrence and reduced acute and late toxicity for pre-operative CRT compared with post-operative CRT [9]. The Cochrane review [4] also examined CRT and concluded that CRT provided incremental benefit in local control, irrespective of the timing of the chemotherapy. These results have led to a significant increase in the use of pre-operative radiation for patients with rectal cancer.MRI offers increased soft-tissue contrast compared with other radiographic imaging modalities such as CT. This improvement allows the accurate identification of the gross tumour and the mesorectal fascia in at least three planes. A number of studies have recommended using high-resolution MRI as a tool to determine the relationship between the potential circumferential resection margin (CRM) and the tumour [10-15], with one recent large prospective multicentre study demonstrating a specificity of 92% in predicting an involved CRM [16]. These results are supported by a recent meta-analysis of nine studies (529 patients) that revealed an overall sensitivity of 94% and specificity of 85% [17]. The review article by Klessen et al [18] also suggests that MRI is the only imaging modality that enables such accurate evaluation. Consequently, MRI is the reference standard for the clinical assessment of patients with colorectal cancer and is recommended for routine use by the National Institute for Clinical Excellence (NICE) in the UK [19].Current clinical practice at St James’s Institute of Oncology is for patients to be selected for pre-operative CRT if the margins of resection are considered at risk by the colorectal multidisciplinary team. The patient is CT-scanned in the prone treatment position and the oncologist defines the gross tumour volume (GTV) on individual transaxial images, leading to the determination of the planning target volume (PTV). To assist in the definition of the GTV, the oncologist is aided by diagnostic CT and/or MRI and other clinical information. Where diagnostic MRI is available, it is usually acquired in a different patient orientation (e.g. supine position) or radiographic plane (e.g. orthogonal to the long axis of the tumour) and at a different time to the CT study, meaning that the anatomy may differ in appearance. Furthermore, the MRI may be on radiographic film or on a different computer system to the planning CT.Image co-registration is the process of finding the mathematical transformation that aligns several different radiographic studies [20]. Various rigid-body co-registration techniques are currently offered by commercial RT treatment planning systems (TPSs), including those that employ operator-defined corresponding landmarks, interactive drag-and-drop or full automation.There are obvious potential advantages of including image registration in the treatment planning process [21], but historically, technical issues associated with MRI distortion, artefacts and lack of electron density information, along with little evidence of its positive effect on patient outcome, are likely to have precluded its universal use in treatment planning [22]. Despite these issues, studies have demonstrated the feasibility of pelvic image registration for RT treatment planning [23-26].Furthermore, rectal cancer specifically has been identified as a disease for which co-registered MRI could enhance treatment planning [27,28]. There is considerable interest in RT in which the GTV is defined on MR imaging in the same frame of reference as the planning CT. Increased accuracy in defining the GTV and/or clinical target volume (CTV) would give a more accurate definition of the dose required to those volumes or allow dose escalation to the GTV in patients with locally advanced disease. Acquiring an MRI with the patient in the prone position, however, introduces a new set of potential challenges, including increased respiratory artefacts that affect registration accuracy.Several studies have investigated the accuracy of image registration in a RT context, but as concluded by Sharpe and Brock [29] in their review of image registration quality assurance, there is no consistent approach. One approach is to image phantoms with objects of known spatial location with both CT and MRI [30-33]. This has the advantage of enabling controlled measurement of errors throughout the entire process of image acquisition and image registration, with a ground truth established through the objects with known spatial location. Such phantoms can also be used to estimate the spatial distortion in the images. However, these studies are all based on the use of MRI to image the head and neck rather than the pelvis. The studies’ dependence on physical phantoms means that uncertainties that may arise from natural variations in shape, size and composition in the patient population are not measured. Furthermore, the two studies evaluating the performance of commercial registration algorithms using patient images are both based on the registration of images of the head [32,34].Several studies have employed CT-MRI co-registration for pelvic sites [23-26,35,36], but few data exist on measured image registration uncertainties using existing image registration functionality in commercial TPSs. Furthermore, no evidence could be found of image registration for patients imaged in the prone position.The primary aim of this study is to assess the co-registration accuracy of two fully automated and two hybrid manual-automatic techniques using two commercial TPSs. On the basis of these results, this study aims to determine the most appropriate clinical image registration process and whether manual adjustments after automatic image registration are necessary or even beneficial. It is expected to provide supporting information for RT centres that are considering utilising co-registered prone MRI in treatment planning for rectal cancer.     

Radio-guided occult lesion localisation for breast lesions under computer-aided MRI guidance: the first experience and initial results

Objective

The purpose of this study was to present an alternative technique for the pre-operative localisation of solely MRI-detected suspicious breast lesions using a computer-assisted MRI-guided radio-guided occult lesion localisation (ROLL) technique.

Methods

Between January 2009 and June 2010, 25 females with a total of 25 suspicious breast lesions that could be detected only by MRI, and for whom breast surgery was planned, underwent the computer-assisted MRI-guided ROLL technique. A seven-channel biopsy breast array coil and computerised diagnostic workstation were used for the localisation procedure. Three-phase dynamic contrast-enhanced axial images were taken. After investigating the localisation co-ordinates with the help of intervention software on a workstation, an 18 G coaxial cannula was placed in the exact position determined. Following verification of the cannula position by additional axial scans, ^99mTc-labelled macroalbumin aggregate and MRI contrast material were injected. Post-procedure MRI scans were used to confirm the correct localisation.

Results

All the procedures were technically successful. The mean lesion size was 10.8 mm (range: 4–25 mm). The mean total magnet and the mean localisation times were 28.6 min (range: 18–46 min) and 13.1 min (range: 8–20 min), respectively. Grid and pillar methods were used for localisation in 24 procedures and 1 procedure, respectively. On histopathological examination, 6 malignant, 10 high-risk and 9 benign lesions were identified. All patients tolerated the procedure well. There were no major complications.

Conclusion

This is the first report documenting the application of MRI-guided ROLL. Based on our preliminary results, this technique is very efficient and seems to be a good alternative to wire localisation.MRI of the breast has now become an integral and necessary component of breast imaging practice [1]. It is a valuable tool with high sensitivity for the identification of breast cancer in high-risk patients, follow-up of patients with known breast cancer and in patients at a pre-operative stage in order to rule out any ipsilateral or contralateral disease [2-5]. It can detect suspicious breast lesions that are occult to clinical examination, mammography and ultrasonography [4,6,7]. It was reported that, although the addition of MRI to current evaluation (clinical, radiological and pathological) has no benefit on a reduction of operation rates, cost-effectiveness and quality of life, it has the potential to aid tumour localisation [8].An MRI-guided intervention is necessary to make a definitive histological diagnosis of such “solely” MRI-detected suspicious breast lesions. Histopathological assessment can be performed by MRI-guided wire localisation followed by surgical excision [6,9,10], or by alternative techniques to surgery such as MRI-guided percutaneous biopsy using fine needles [11], core needles [12,13] or vacuum-assisted biopsy devices [7,14]. For such a breast intervention to be clinically useful, factors such as safety, accuracy, availability, cost, patient preference for surgical biopsy and surgeon''s request should be considered. With fine or core needle, lesions measuring <1 cm may not always be accurately sampled, and vacuum biopsy would bring an extra cost burden if surgical biopsy is already planned.MRI-guided wire localisation is a well-known (and currently the most commonly utilised) technique. Several authors have reported success with this technique for surgical biopsy [6-10]. According to them, it can be performed quickly and safely with relatively simple methods and commercially available equipment. However, this technique harbours several limitations and poses potential challenges during and/or after its application, such as the necessity to perform surgery on the same day owing to the risk of wire migration and/or accordion effect [6], breast pain, and poor cosmetic outcome after surgery [15].Radio-guided occult lesion localisation (ROLL) has been documented as a more reliable and effective method than wire for the identification of non-palpable breast lesions [16,17]. Routine ROLL involves the injection of ^99mTc-labelled human serum albumin into the suspicious lesion under ultrasonography or mammography control within 24 h prior to surgery. Subsequently, surgical excision is performed with the help of a hand-held gamma probe [18].To the best of our knowledge, ROLL has never been reported as an adjunct for the pre-operative localisation of solely MRI-detected suspicious breast lesions. Thus, the purpose of this study was to introduce a new technique—computer-aided and MRI-guided ROLL—to present its technical aspects and document our initial results.     

Prostatic cancer surveillance following whole-gland high-intensity focused ultrasound: comparison of MRI and prostate-specific antigen for detection of residual or recurrent disease

Objective

This retrospective study compares dynamic contrast-enhanced (DCE) MRI with the serial prostate-specific antigen (PSA) measurement for detection of residual disease following whole-gland high-intensity focused ultrasound (HIFU) therapy of prostate cancer.

Methods

Patients in whom post-HIFU DCE-MRI was followed within 3 months by ultrasound-guided transrectal biopsy were selected from a local database. 26 patients met the study inclusion criteria. Serial PSA levels following HIFU and post-HIFU follow-up MRI were retrieved for each patient. Three radiologists unaware of other investigative results independently assessed post-HIFU MRI studies for the presence of cancer, scoring on a four-point scale (1, no disease; 2, probably no disease; 3, probably residual disease; and 4, residual disease). Sensitivity, specificity and receiver operating characteristic (ROC) analysis were performed for each reader, post-HIFU PSA nadir and pre-biopsy PSA level thresholds of >0.2 and >0.5 ng ml⁻¹.

Results

The sensitivity of DCE-MRI for detection of residual disease for the three readers ranged between 73% and 87%, and the specificity between 73% and 82%. There was good agreement between readers (κ=0.69–0.77). The sensitivity and specificity of PSA thresholds was 60–87% and 73–100%, respectively. The area under the ROC curve was greatest for pre-biopsy PSA (0.95).

Conclusion

DCE-MRI performed following whole-gland HIFU has similar sensitivity and specificity and ROC performance to serial PSA measurements for detection of residual or recurrent disease.High-intensity focused ultrasound (HIFU) is a promising alternative management paradigm for prostate cancer available to patients with organ-confined disease. Whole-gland treatment is achievable while sparing the neurovascular bundles and external urethral sphincter [1,2]. As a result, reported rates of urinary and sexual morbidity are lower and quality of life higher following HIFU therapy than following radical prostatectomy [3].However, recurrence rates as high as between 30% and 40% at 5 years have been reported [4]. Identification of potential residual or recurrent disease is therefore paramount, guiding administration of salvage therapy [5]. Accepted surveillance for residual or recurrent tumour following whole-gland HIFU is reliant on serial prostate-specific antigen (PSA) measurements followed by biopsy for patients with a high or rising PSA [6].There are several potential advantages of assessing post-HIFU residual disease with MRI. First, MRI may provide a more sensitive test than PSA, as it is able to detect disease not elevating PSA but causing a change in the MRI features of residual prostatic tissue. Second, when disease is detected on MRI, it is clear that imaging also provides the location of disease and therefore has the added advantage of being able to guide biopsy and salvage therapy. Finally, as primary focal treatment (e.g. hemi-ablation) of prostate cancer becomes established [7], it is highly likely that identification of residual disease by PSA alone will become more difficult, as PSA from untreated prostate may mask residual disease. Development of an imaging-based alternative for detection of residual or recurrent disease in the post-HIFU prostate is therefore necessary.Dynamic contrast-enhanced (DCE) MRI has been used for detection of cancer in the untreated prostate, and has performance characteristics similar to gland biopsy [8]. DCE-MRI has also been reported to detect residual disease after radiotherapy [9]. Moreover, early studies investigating DCE-MRI in patients treated with whole-gland HIFU have shown promising results for detection of residual tumour [6,10].Our study assesses the performance of DCE-MRI to detect residual or recurrent disease in the post-HIFU (whole-gland) prostate, and compares this with serial PSA measurement.