The effect of Premium View post-processing software on digital mammographic reporting

The aim of this study was to identify the effect of the installation of Premium View post-processing software on our mammographic reporting performance, in particular the effects on our recall rate, biopsy rate and cancer detection rate. The case notes and imaging of all patients discussed at the weekly indeterminate imaging multidisciplinary team meeting were reviewed retrospectively before, immediately after and at a delayed interval following the installation of Premium View post-processing software. Factors recorded included the mammographic abnormality, further investigations and final histology. The indeterminate mammogram rate increased significantly from a baseline of 5.7% (before Premium View) to 8.7% in the time period immediately after the installation of Premium View (p _ 0.002). The stereotactic biopsy rate also increased from 0.8% to 2.4% (p _ 0.001), with a significant increase in the overall cancer detection rate from 3.4% to 4.4% (p _ 0.02). In the follow-up period several months after the installation of Premium View, the indeterminate mammogram rate returned to a level similar to that before Premium View (6%; p _ 0.7). The stereotactic biopsy rate remained significantly higher at 1.6% (p _ 0.07), as did the overall cancer detection rate of 5.0% (p _ 0.003). In conclusion, the use of Premium View may lead to higher cancer detection rates, at the expense of an initial increase in recall rate. Although prospective studies are suggested, this result is of interest in light of the proposed installation of digital mammography across the NHS Breast Screening Programme.Image quality is of paramount importance in mammography, and it has long been recognised that full-field digital mammography (FFDM) has many potential advantages over conventional screen–film mammography (SFM) [1–5]. A number of large studies have fully evaluated the diagnostic performance of this technology, notably the Digital Mammographic Imaging Screening Trial (DMIST), which showed the overall diagnostic accuracy of digital and film mammography as a means of screening for breast cancer to be similar, but digital mammography as more accurate in women under the age of 50 years, women with radiographically dense breasts and pre- or peri-menopausal women [5]. Several other studies have also looked at the use of digital mammography in screening, supporting the fact that FFDM is at least equal to SFM; the effect on recall rate, however, has varied. The Oslo I study comprised 3683 women aged 50–60 years and found no significant difference in cancer detection rates [3]. Direct side-by-side cancer conspicuity was equal; however, the recall rate for FFDM was slightly higher (4.6% vs 3.5%). Another paired screening study by Lewin et al [6] involving 6736 paired screen–film and digital mammography examinations performed in 4489 women again found no significant difference in cancer detection rates between the two modalities. In this study, however, the recall rate for FFDM was significantly lower than for SFM (11.8% vs 14.9%; p<0.001). More recently, the Oslo II study [4], a randomised trial involving more than 25 000 women attending for screening, found that the cancer detection rate for FFDM was superior to SFM in women aged 50–60 years (0.83% vs 0.54%). This almost reached statistical significance (p _ 0.053). For younger women aged 45–49 years, cancer detection rate was almost equal (0.27% vs 0.22%); however, the recall rate was significantly higher in both age groups for FFDM (p<0.05). Initial Food and Drug Administration (FDA) trials comparing FFDM and SFM in symptomatic patients found no significant difference in sensitivity or specificity [7, 8]. However, faster image acquisition associated with FFDM leads to increased productivity of a department and is of particular benefit for patients undergoing needle localisation procedures. By decoupling the tasks of image capture and display, both dynamic range and contrast resolution can be optimised, without the typical trade-off encountered in SFM [9, 10]. It avoids the problem of film artefact encountered in SFM and allows multiple ways of enhancing image quality after processing: the ability to change window width and lengths, roam and zoom images and apply post-processing algorithms to equalise tissue thickness or highlight specific features. As well as having the potential to improve image quality, this may impact favourably on overall dose to the patient. FFDM allows more efficient storage and transmission of data, enabling comparison of images across sites, and facilitates the use of computer-aided detection [11–13].One area in which FFDM is surpassed by SFM is that of spatial resolution: SFM limiting resolution is typically 12–16 lpmm^–1; that for FFDM is 5–10 lp mm^–1. However, because lesions such as microcalcification become fainter as they become smaller, it is contrast resolution rather than spatial resolution that limits detectability [14, 15].At our institution, we perform daily symptomatic breast clinics and have used GE FFDM equipment for more than seven years, thereby making us one of the most experienced units in using this technology in the UK. A year ago, we implemented “Premium View” software as part of a system and workstation upgrade. Premium View is a state-of-the-art post-processing breast algorithm developed by GE Medical Systems (GEMS, Waukesha, WI) to increase radiologists'' diagnostic confidence by optimising mammographic image contrast resolution. It is offered as standard software on the Senographe DS unit and is additional to the thickness equalisation algorithm originally introduced with the Senographe 2000D unit. The aim of this study was to identify the effect of installation of Premium View on our mammographic reporting performance, in particular the effects on our recall rate for indeterminate mammography, as well as our biopsy rate and subsequent cancer detection rate.     

New methods for using computer-aided detection information for the detection of lung nodules on chest radiographs

Objective:

To investigate two new methods of using computer-aided detection (CAD) system information for the detection of lung nodules on chest radiographs. We evaluated an interactive CAD application and an independent combination of radiologists and CAD scores.

Methods:

300 posteroanterior and lateral digital chest radiographs were selected, including 111 with a solitary pulmonary nodule (average diameter, 16 mm). Both nodule and control cases were verified by CT. Six radiologists and six residents reviewed the chest radiographs without CAD and with CAD (ClearRead +Detect™ 5.2; Riverain Technologies, Miamisburg, OH) in two reading sessions. The CAD system was used in an interactive manner; CAD marks, accompanied by a score of suspicion, remained hidden unless the location was queried by the radiologist. Jackknife alternative free response receiver operating characteristics multireader multicase analysis was used to measure detection performance. Area under the curve (AUC) and partial AUC (pAUC) between a specificity of 80% and 100% served as the measure for detection performance. We also evaluated the results of a weighted combination of CAD scores and reader scores, at the location of reader findings.

Results:

AUC for the observers without CAD was 0.824. No significant improvement was seen with interactive use of CAD (AUC = 0.834; p = 0.15). Independent combination significantly improved detection performance (AUC = 0.834; p = 0.006). pAUCs without and with interactive CAD were similar (0.128), but improved with independent combination (0.137).

Conclusion:

Interactive CAD did not improve reader performance for the detection of lung nodules on chest radiographs. Independent combination of reader and CAD scores improved the detection performance of lung nodules.

Advances in knowledge:

(1) Interactive use of currently available CAD software did not improve the radiologists'' detection performance of lung nodules on chest radiographs. (2) Independently combining the interpretations of the radiologist and the CAD system improved detection of lung nodules on chest radiographs.Chest radiography can be considered the workhorse of the radiology department. It is being used for the detection and diagnosis of multiple diseases, including lung nodules, which may represent early lung cancer. Since a chest radiograph is a two-dimensional image, overprojection of multiple anatomical structures is inevitable. This so-called anatomical noise substantially impedes interpretation of chest radiographs. Multiple studies have shown that a substantial amount of lung cancers are missed, ranging from 19% to 26%,^1,2 and even up to 90%.^3–5 More recent studies have shown that the problem of missing lung nodules is still present with the most modern digital radiographic technology.^6,7 Abnormalities can be missed as a result of inadequate search, perception errors or interpretation errors. It has been stated that interpretation by the radiologist is the most important factor for missing lung cancer on chest radiographs.^8,9To reduce miss rates, computer-aided detection (CAD) systems have been developed. Thus far, all studies dealing with chest radiography apply CAD as a second reader to the radiologist, meaning that the CAD marks are made available only after the radiologist has made a primary review. It remains the reader''s discretion to accept or disregard the CAD marks. Results of these studies were contradictory: some found an increased accuracy for the detection of lung nodules,^10–12 whereas other studies reported an increase in sensitivity only at the expense of loss in specificity.^13–16 One problem ameliorating the potential of CAD is the radiologist''s limited ability to reliably discriminate between true-positive (TP) and false-positive (FP) CAD marks.We therefore decided to explore alternative methods of using CAD information. First, we used CAD interactively. In the interactive mode, CAD marks remained hidden unless the radiologist queried a position in the image by clicking with the mouse on that location. If a CAD mark was present in this location, it was shown to the radiologist together with a score of suspicion. Such an interactive CAD system had been shown to be beneficial in chest radiography in an observer study that only used non-radiologists.¹⁷ Second, we computed a mathematical combination of reader and CAD scores. With this method, observers did not need to view the CAD marks at all during their reading of the images, but a mathematical combination of the reader and the CAD scores was computed afterwards. Both methods have been reported to outperform the use of CAD as a second reader for lesion detection in mammograms.^18–20The purpose of this observer study was to test the impact of these two alternative methods of using CAD information on nodule detection on chest radiographs. To optimize baseline performance without CAD, digitally bone-suppressed images (BSIs) were added to the original chest radiographs. BSIs have been shown to improve accuracy for the detection of focal lesions on chest radiographs;^21–24 a further increase in detection performance beyond that of BSIs by adding CAD has also been documented.²⁵     

Computer-aided detection of breast masses depicted on full-field digital mammograms: a performance assessment

Objectives

To investigate the feasibility of converting a computer–aided detection (CAD) scheme for digitised screen–film mammograms to full-field digital mammograms (FFDMs) and assessing CAD performance on a large database.

Methods

The database included 6478 FFDM images acquired on 1120 females, with 525 cancer cases and 595 negative cases. The database was divided into five case groups: (1) cancer detected during screening, (2) interval cancers, (3) “high-risk” recommended for surgical excision, (4) recalled but negative and (5) negative (not recalled). A previously developed CAD scheme for masses depicted on digitised images was converted and re-optimised for FFDM images while keeping the same image-processing structure. CAD performance was analysed on the entire database.

Results

The case-based sensitivity was 75.6% (397/525) for the current mammograms and 40.8% (42/103) for the prior mammograms deemed negative during clinical interpretation but “visible” during retrospective review. The region-based sensitivity was 58.1% (618/1064) for the current mammograms and 28.4% (57/201) for the prior mammograms. The CAD scheme marked 55.7% (221/397) and 35.7% (15/42) of the masses on both views of the current and the prior examinations, respectively. The overall CAD-cued false-positive rate was 0.32 per image, ranging from 0.29 to 0.51 for the five case groups.

Conclusion

This study indicated that (1) digitised image-based CAD can be converted for FFDMs while performing at a comparable, or better, level; (2) CAD detects a substantial fraction of cancers depicted on prior examinations, albeit most having been marked only on one view; and (3) CAD tends to mark more false-positive results on “difficult” negative cases that are more visually difficult for radiologists to interpret.During the last decade, commercialised computer-aided detection (CAD) systems were widely tested and used clinically as a “second reader” to assist radiologists in interpreting mammograms. These CAD systems process digitised or digital images and cue (mark) suspicious regions that may depict specific abnormalities (i.e. masses and/or microcalcification clusters). The second reader approach emphasises that radiologists should first read and interpret mammograms without CAD followed by the viewing of the CAD results to help highlight the regions that were missed and/or underestimated in their importance prior to making a final recommendation. A number of studies have assessed the impact of using CAD on radiologists'' performances when interpreting mammograms [1-6]. Some studies have shown that radiologists detected more cancers associated with microcalcifications when using CAD for both screen–film mammograms (SFMs) [1] and full-field digital mammograms (FFDMs) [6], while other studies have shown that the use of CAD had little impact on both cancer detection and recall rates of the radiologists [2], or even reduced radiologists'' performances as measured by the areas under the receiver operating characteristic (ROC) curves [5]. Although there is no universal agreement of the actual benefit, if any, when using CAD, in terms of performance improvement [7], the objective assessment of CAD performance alone is important and has scientific merit. Our own previous study demonstrated an improvement in radiologists'' performances when using “highly performing” CAD, whereas radiologists'' performances actually reduced when using “poorly performing” CAD with high false-positive cueing rates [8].A number of previous studies have assessed the performances of commercialised CAD systems alone using different image databases [9-15]. Among these, several studies assessed the performances of CAD systems for FFDM images. One study reported an 89% (32/36) case-based sensitivity at 0.29 false-positive mass cues per image using the ImageChecker M1000-DM system (v.3.1; Hologic Inc., Bedford, MA) [13], and another study reported a 92% (57/62) case-based sensitivity at an overall false-positive rate of 0.58 per image (including both false-positive mass and microcalcification cluster cues) using the SecondLook system (v.7.2; iCAD Inc., Nashua, NH) [14]. Recently, Sadaf et al [15] reported the largest retrospective study to evaluate CAD performance using FFDM images to date. The database included 127 verified cancer cases associated with 5 different types of abnormalities. The CAD scheme (SecondLook v.7.2) achieved overall a 91% (115/127) cancer detection sensitivity, or an 88% (44/51) sensitivity on malignant masses.As the majority of previously reported CAD schemes in mammography were developed for digitised SFM images, researchers have also investigated the feasibility of converting the CAD schemes developed for digitised SFM images to new CAD schemes for FFDM images and comparing the performance difference between the CAD schemes for these two types of images [16,17]. For example, one study reported that two CAD schemes with similar architecture achieved comparable performance levels for the FFDM and SFM images (e.g. 70% sensitivity at 0.9 and 1.0 false-positive marks per image) by using a database of 229 SFM and FFDM examinations depicting 27 malignant and 104 benign masses [16]. Another study investigated the feasibility of converting an SFM-based CAD scheme to classify between malignant and benign masses depicted on FFDM images without changing the structure of the CAD scheme. Using a data set depicting 148 malignant and 139 benign masses, the study reported that there was no significant difference from the result of a previous study using SFM images (with an area under the ROC curve of 0.81 and p=0.83) [17].Despite these research efforts and the reported high performances, the databases used in the previous studies [13-17] were limited. In the assessment of CAD performance using digitised SFM images, studies have shown that the higher sensitivity reported in a study using a limited database (i.e. 89% [9]) was often not achievable in large-scale assessment studies [1,11,12]. Therefore, owing to the large variation of breast abnormalities and normal tissue structures, assembling a large database that can relatively sufficiently represent the general screening population is important to effectively assess or predict CAD performance in clinical practice. In this study, we assembled a large and unique FFDM image database that included a series of mammographic examinations on the same females belonging to one of five categories (groups) and converted our in-house developed CAD scheme for SFM images into a new scheme for FFDM images. An assessment of the CAD performance levels on the entire FFDM image database and each of the five case groups, at an operating level similar to that previously used to assess commercial CAD schemes for SFM images [12], is described herein.     

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.     

Estimation of percentage breast tissue density: comparison between digital mammography (2D full field digital mammography) and digital breast tomosynthesis according to different BI-RADS categories

Objective:

To compare breast density estimated from two-dimensional full-field digital mammography (2D FFDM) and from digital breast tomosynthesis (DBT) according to different Breast Imaging–Reporting and Data System (BI-RADS) categories, using automated software.

Methods:

Institutional review board approval and written informed patient consent were obtained. DBT and 2D FFDM were performed in the same patients to allow within-patient comparison. A total of 160 consecutive patients (mean age: 50±14 years; mean body mass index: 22±3) were included to create paired data sets of 40 patients for each BI-RADS category. Automatic software (MedDensity^©, developed by Giulio Tagliafico) was used to compare the percentage breast density between DBT and 2D FFDM. The estimated breast percentage density obtained using DBT and 2D FFDM was examined for correlation with the radiologists'' visual BI-RADS density classification.

Results:

The 2D FFDM differed from DBT by 16.0% in BI-RADS Category 1, by 11.9% in Category 2, by 3.5% in Category 3 and by 18.1% in Category 4. These differences were highly significant (p<0.0001). There was a good correlation between the BI-RADS categories and the density evaluated using 2D FFDM and DBT (r=0.56, p<0.01 and r=0.48, p<0.01, respectively).

Conclusion:

Using DBT, breast density values were lower than those obtained using 2D FFDM, with a non-linear relationship across the BI-RADS categories. These data are relevant for clinical practice and research studies using density in determining the risk.

Advances in knowledge:

On DBT, breast density values were lower than with 2D FFDM, with a non-linear relationship across the classical BI-RADS categories.To tailor screening and diagnosis protocols, it is important to identify females with an increased risk of breast cancer [1–3]. It has been estimated that females with dense breasts (breast densities of >75%) have 4–6 times higher risk of breast cancer than females with low breast densities [4] and that breast density is increasingly recognised as an independent determinant of breast cancer risk and possibly in prognosis [5]. Assessment of breast density is becoming crucial in epidemiological studies, including the estimation of breast cancer risk and assessing breast density-related risk over time, radiation dose monitoring and monitoring drug-related response [6,7].Different methods and classifications have been reported to assess breast density: the Tabar classification [8], Wolfe''s parenchymal patterns [9], and both semi-quantitative and quantitative computer-aided techniques [10–16]. The Breast Imaging–Reporting and Data System (BI-RADS) classification, considered as the additional quantitative scheme, is routinely used in the USA and was introduced to standardise reporting. Initially, it was based on four qualitative categories but an additional quantitative scheme was added in 2003, based on the extent of fibroglandular tissue [17]. Mammographic breast density estimation may be limited by the two-dimensional (2D) nature of the imaging technique, whereas a three-dimensional (3D) imaging modality, such as digital breast tomosynthesis (DBT), reduces the appearance of the overlapping parenchymal tissue and may therefore influence or alter density assessments [13,14]. In DBT, high-spatial-resolution tomographic images of the breast are reconstructed from multiple low-dose projection images acquired within a limited range of X-ray tube angles [15]. It has been demonstrated in a few studies that the automated estimation of breast density eliminates subjectivity between comparisons of full-field digital mammography (2D FFDM) and DBT and is more reproducible than a quantitative BI-RADS evaluation [14,16]. However, previous research mainly considered patients with relatively high breast density, with the possibility of the results not being applicable across all density categories and showing whether published percentage breast density differences between 2D FFDM and DBT apply to less dense or non-dense breasts. The purpose of our study was to compare the breast tissue density estimated using 2D FFDM and DBT among patients in a balanced data set of the four BI-RADS categories, using fully automated software.     

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.     

Comparison of mammography, sonography, MRI and clinical examination in patients with locally advanced or inflammatory breast cancer who underwent neoadjuvant chemotherapy

Objectives

The purpose of this study was to determine the relative accuracies of mammography, sonography, MRI and clinical examination in predicting residual tumour size and pathological response after neoadjuvant chemotherapy for locally advanced or inflammatory breast cancer. Each prediction method was compared with the gold standard of surgical pathology.

Methods

43 patients (age range, 25–62 years; mean age, 42.7 years) with locally advanced or inflammatory breast cancer who had been treated by neoadjuvant chemotherapy were enrolled prospectively. We compared the predicted residual tumour size and the predicted response on imaging and clinical examination with residual tumour size and response on pathology. Statistical analysis was performed using weighted kappa statistics and intraclass correlation coefficients (ICC).

Results

The ICC values between predicted tumour size and pathologically determined tumour size were 0.65 for clinical examination, 0.69 for mammography, 0.78 for sonography and 0.97 for MRI. Agreement between the response predictions at mid-treatment and the responses measured by pathology had kappa values of 0.28 for clinical examination, 0.32 for mammography, 0.46 for sonography and 0.68 for MRI. Agreement between the final response predictions and the responses measured by pathology had kappa values of 0.43 for clinical examination, 0.44 for mammography, 0.50 for sonography and 0.82 for MRI.

Conclusion

Predictions of response and residual tumour size made on MRI were better correlated with the assessments of response and residual tumour size made upon pathology than were predictions made on the basis of clinical examination, mammography or sonography. Thus, the evaluation of predicted response using MRI could provide a relatively sensitive early assessment of chemotherapy efficacy.The advantages of neoadjuvant chemotherapy are multiple and it has been used widely during the past few years [1]. Its primary role is to induce tumour shrinkage and permit breast-conserving surgery, primarily in patients with advanced breast cancer [2-4]. Neoadjuvant chemotherapy allows earlier treatment of micrometastatic disease and the study of biological markers that might predict tumour response [5]. The effectiveness of chemotherapeutic agents in treating both primary breast cancer and potential metastatic disease may be enhanced by the presence of tumour neovascularity. If chemotherapy is given before surgery, while tumour vascularity remains intact, the chemotherapeutic agents may be better able to reach the tumour and thus be more effective.Neoadjuvant chemotherapy of locally advanced breast cancer (LABC) has also been shown to improve the resectability rate, offering disease-free and overall survival rates that are at least equivalent to those offered by surgery alone [6,7]. Pathological complete response (pCR) is clinically significant because it is associated with improved long-term prognosis and decreased risk of recurrence [6,8]. Decisions regarding the continuation of current regimens and the appropriate type and timing of surgery depend on the radiological and clinical assessment of residual tumour size during neoadjuvant chemotherapy [9,10]. Until now, many studies have shown that physical examinations, mammography and sonography provide suboptimal evaluations of lesion extent that do not allow accurate assessments of pathological response or residual tumour size [5^,11-13]. In the case of LABC, physical examination, mammography or sonography may be suitable for detecting the larger lesions of non-responders, but they have limited sensitivity for responders with smaller residual lesions [14,15]. For mammography, calcifications may persist or even increase in patients who respond to neoadjuvant chemotherapy [14,16,17].Many previous studies have shown that MRI is the most reliable technique for evaluating residual disease after neoadjuvant chemotherapy, although initial reports described frequent false-negatives with smaller-volume disease [18-27]. Recent studies have increased the sensitivity of MRI, with increased resolution, reduced slice thickness and lower enhancement thresholds being used to minimise the underestimation of residual disease [15^,22-27]. It is still difficult, however, to distinguish residual scarring, necrosis and fibrosis from viable residual malignancy and to predict accurate response after neoadjuvant chemotherapy, especially in responders. Few published studies have described work with patients with inflammatory breast cancer who underwent neoadjuvant chemotherapy because the incidence of this disease is very low [28,29]. The purpose of our study was to determine the relative accuracies of mammography, sonography, MRI and clinical examination in predicting residual tumour size and pathological response after neoadjuvant chemotherapy for locally advanced and inflammatory breast cancer. We compared each prediction method with the gold standard of surgical pathology.     

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.     

Impact of biplane versus single-plane imaging on radiation dose,contrast load and procedural time in coronary angioplasty

Coronary angioplasties can be performed with either single-plane or biplane imaging techniques. The aim of this study was to determine whether biplane imaging, in comparison to single-plane imaging, reduces radiation dose and contrast load and shortens procedural time during (i) primary and elective coronary angioplasty procedures, (ii) angioplasty to the main vascular territories and (iii) procedures performed by operators with various levels of experience. This prospective observational study included a total of 504 primary and elective single-vessel coronary angioplasty procedures utilising either biplane or single-plane imaging. Radiographic and clinical parameters were collected from clinical reports and examination protocols. Radiation dose was measured by a dose–area–product (DAP) meter intrinsic to the angiography system. Our results showed that biplane imaging delivered a significantly greater radiation dose (181.4±121.0 Gycm²) than single-plane imaging (133.6±92.8 Gycm², p<0.0001). The difference was independent of case type (primary or elective) (p = 0.862), vascular territory (p = 0.519) and operator experience (p = 0.903). No significant difference was found in contrast load between biplane (166.8±62.9 ml) and single-plane imaging (176.8±66.0 ml) (p = 0.302). This non-significant difference was independent of case type (p = 0.551), vascular territory (p = 0.308) and operator experience (p = 0.304). Procedures performed with biplane imaging were significantly longer (55.3±27.8 min) than those with single-plane (48.9±24.2 min, p = 0.010) and, similarly, were not dependent on case type (p = 0.226), vascular territory (p = 0.642) or operator experience (p = 0.094). Biplane imaging resulted in a greater radiation dose and a longer procedural time and delivered a non-significant reduction in contrast load than single-plane imaging. These findings did not support the commonly perceived advantages of using biplane imaging in single-vessel coronary interventional procedures.The use of biplane imaging during diagnostic coronary angiography and coronary interventions has been reported to reduce the total contrast load to the patient compared with single-plane imaging [1–8]. Additionally, acquiring two simultaneous images from two orthogonal planes has been reported to be more efficient than single-plane imaging [2, 8–11]. However, there are conflicting reports as to whether the radiation dose to the patient differs between biplane and single-plane imaging during coronary studies [3, 10, 11].Biplane imaging allows two cineangiography runs to be recorded simultaneously with a single injection of contrast. With single-plane imaging, however, the same information can be acquired only by carrying out the two cineangiography runs serially with two separate injections of contrast [1, 2, 8, 10]. Biplane imaging enables the operator to visualise the target lesion in orthogonal planes simultaneously and was presumed to be more efficient than single-plane imaging, particularly in difficult procedures [1, 4, 9, 12]. Accordingly, examinations would become faster, use of fluoroscopy would be reduced, fewer cineangiography runs would be required and the average radiation dose to the patient would be comparatively lower than in the case of procedures performed with single-plane imaging. The contrast load with biplane imaging was also expected to be significantly reduced [3, 4, 11].These perceived advantages of biplane imaging have led to recommendations for its use in paediatric and adult cardiac catheter laboratories [1, 4, 5, 10, 12, 13]. A previous study comparing biplane and single-plane imaging in 1156 diagnostic coronary angiography procedures found a small, but notable, reduction in contrast load accompanied by significantly longer table times and screening times with biplane imaging, although radiation dose was not examined [14].Contrast-induced nephropathy (CIN) is a complication associated with prolonged hospitalisation and development of end-stage renal failure [15]. Patients with pre-existing renal disease, diabetes, congestive heart failure or older age are at the greatest risk in developing CIN [16–18]. These high-risk patients have a calculated incidence of CIN ranging from 10% to 30% [4, 18–20]. Pre-hydration is the primary intervention for preventing contrast nephropathy [18], but is not possible in the setting of emergency (primary) angioplasty procedures. The total contrast load during interventional procedures has been established as an independent predictor of CIN and could be effectively controlled by the operator during primary angioplasty cases [18, 21, 22]. Biplane imaging is commonly employed to minimise the contrast load, especially in patients with renal impairment and those who require primary coronary angioplasty procedures [1, 6, 7, 18, 23].Numerous studies have found that the radiation dose varies significantly according to tube angulations, particularly in the combination of steep left anterior oblique (LAO) with cranial or caudal angulations [24–27]. However, there are no published data on whether the radiation dose with biplane or single-plane imaging during coronary angioplasty differs between the three vascular territories: right coronary artery (RCA), left anterior descending (LAD) and left circumflex/intermediate (LCX). Furthermore, interventional cardiac procedures are operator dependent [28–30]. Hence, it was postulated that senior cardiologists would be more familiar with biplane equipment and thereby more able to reduce radiation dose, contrast load and procedural time than less experienced operators. To our knowledge, no studies have been published that compare the impact of biplane and single-plane imaging in coronary angioplasty procedures.The aims of this study were to determine whether biplane imaging reduces both contrast load and radiation dosage and shortens procedural time in patients undergoing primary or elective coronary angioplasty compared with single-plane imaging. We also investigated if there was a significant difference in radiation dose, contrast load and procedural time between biplane and single-plane imaging during coronary angioplasty in the three main vascular territories (RCA, LAD and LCX) and in procedures performed by operators with various levels of experience.     

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.     

Breast-specific gamma imaging as an adjunct modality for the diagnosis of invasive breast cancer with correlation to tumour size and grade

Objectives

The purpose of this study was to determine the sensitivity of breast-specific gamma imaging (BSGI) in the detection of invasive breast cancers and to characterise the sensitivity of BSGI based on tumour size and pathological grade.

Methods

139 females with invasive carcinoma who underwent BSGI were retrospectively reviewed. Patients were injected in the antecubital vein with 20–30 mCi (925–1110 MBq) of ^99mTc-sestamibi. Images were obtained with a high-resolution, breast-specific gamma camera (Dilon 6800; Dilon Technologies, Newport News, VA) and were categorised based on radiotracer uptake as normal, normal with heterogeneous uptake, probably abnormal and abnormal. For a positive examination, the region of the area of increased uptake had to correlate with the laterality and location of the biopsy-proven cancer.

Results

149 invasive cancers in 139 patients with a mean size of 1.8 cm (0.2–8.5 cm) were included. 146 were identified with BSGI (98.0%). All cancers which measured ≥0.7 cm (n=123) as well as all cancers grade 2 or higher (n=102), regardless of tumour size, were identified with BSGI (100%). There were 6 cancers that were pathological grade 1 and measured <7 mm, of which 50% (3/6) were identified with BSGI. The overall sensitivity of BSGI for the detection of invasive breast cancer is 98.0%. The sensitivity for subcentimetre cancers is 88.5% (23/26).

Conclusion

BSGI has a high sensitivity for the detection of invasive breast cancer. Our results demonstrate that BSGI detected all invasive breast cancers pathological grade 2 and higher regardless of size and all cancers which measured ≥7 mm regardless of grade. BSGI can reliably detect invasive breast cancers and is a useful adjunct imaging modality for the diagnosis of breast cancer.Mammography has remained the modality of choice for breast cancer screening. Nevertheless, it is an imperfect examination with a sensitivity of 78–85% that declines to 68% in females with dense breasts [1-6]. The limitations of mammography have resulted in the development of adjunct imaging modalities to improve breast cancer detection. Most frequently, ultrasound is used in conjunction with mammography as an adjunct imaging modality for breast cancer diagnosis, particularly in females with dense breasts [2].Mammography and ultrasound are both anatomical approaches for the diagnosis of breast cancer. Nuclear medicine techniques that utilise physiological properties of tumours are increasingly being used. A meta-analysis of scintimammographic studies using a traditional, general purpose gamma camera demonstrated an average sensitivity of 84% for breast cancer detection, although many of the cancers included in these studies were palpable and larger [7]. However, scintimammography with a general purpose gamma camera is limited in the detection of non-palpable cancers and cancers less than 1 cm in size because of intrinsic resolution limitations [8-11]. Another limitation is the inability of a general purpose gamma camera to image in positions comparable to those obtained with mammography, limiting the ability to correlate between these two modalities.To overcome the limitations of a traditional gamma camera for the detection of breast cancer, a high-resolution, small-field-of-view gamma camera was developed that allows for the reliable detection of cancers smaller than 1 cm [12]. This technique is referred to as breast-specific gamma imaging (BSGI). Studies with BSGI have demonstrated reliable detection of cancers, both invasive and ductal carcinoma in situ (DCIS), as small as 1 mm [13]. Furthermore, the BSGI camera allows for imaging in positions comparable to mammography, which allows for more direct correlation of mammographic imaging and BSGI [14].An early study using prototype BSGI cameras reported an improvement in the sensitivity for detecting breast cancer when compared with a traditional gamma camera [15]. One study of high-risk females with normal clinical breast examination and a Breast Imaging Reporting and Data System 1 or 2 mammogram demonstrated that BSGI was able to locate occult carcinomas in 13.5% of patients [16]. A recent report demonstrated that BSGI has a sensitivity of 96.4% for invasive carcinoma and 90.9% in DCIS [13,17].The purpose of this study was to investigate the sensitivity of BSGI for invasive breast cancers in the largest reported series to date and to correlate BSGI sensitivity based on tumour pathological size and grade.     

Stand-alone performance of a computer-assisted detection prototype for detection of acute pulmonary embolism: a multi-institutional comparison

Objective

To assess whether the performance of a computer-assisted detection (CAD) algorithm for acute pulmonary embolism (PE) differs in pulmonary CT angiographies acquired at various institutions.

Methods

In this retrospective study, we included 40 consecutive scans with and 40 without PE from 3 institutions (n=240) using 64-slice scanners made by different manufacturers (General Electric; Philips; Siemens). CAD markers were classified as true or false positive (FP) using independent evaluation by two readers and consultation of a third chest radiologist in discordant cases. Image quality parameters were subjectively scored using 4/5-point scales. Image noise and vascular enhancement were measured. Statistical analysis was done to correlate image quality of the three institutions with CAD stand-alone performance.

Results

Patient groups were comparable with respect to age (p=0.22), accompanying lung disease (p=0.12) and inpatient/outpatient ratio (p=0.67). The sensitivity was 100% (34/34), 97% (37/38) and 92% (33/36), and the specificity was 18% (8/44), 15% (6/41) and 13% (5/39). Neither significantly differed between the institutions (p=0.21 and p=0.820, respectively). The mean number of FP findings (4.5, 6.2 and 3.7) significantly varied (p=0.02 and p=0.03), but median numbers (2, 3 and 3) were comparable. Image quality parameters were significantly associated with the number of FP findings (p<0.05) but not with sensitivity. After correcting for noise and vascular enhancement, the number of FPs did not significantly differ between the three institutions (p=0.43).

Conclusions

CAD stand-alone performance is independent of scanner type but strongly related to image quality and thus scanning protocols.Multidetector-row CT (MDCT) has become the first-line diagnostic imaging modality for pulmonary embolism (PE) at most institutions [1-4]. With the technical evolution of MDCT, an increasing number of ever-thinner sections are generated that have to be systematically scrutinised for the presence of emboli in pulmonary arteries. This is a challenging task, especially for smaller and more peripheral pulmonary vessels. As a result, the detection of subsegmental small emboli has a variable interobserver agreement. One study using a 16-slice MDCT scanner reported κ-values ranging from 0.56 to 0.85 [5].The aims of automated computer-assisted detection (CAD) software for pulmonary emboli are to decrease perception errors, to reduce the workload and speed up evaluation, and to make reader performance less dependent on their level of skill or training. The majority of the previously published studies have tested the stand-alone performance of various CAD algorithms [6-13]. Up to now there have been four studies that tested the influence of CAD on radiologists'' detection performance [8,14-16]. However, all studies so far tested the CAD on CT pulmonary angiograms (CTPAs) from a single institution.It is likely that the quality of the CTPA influences the performance of the CAD algorithm. Poorly timed contrast, motion artefacts, noise and the presence of accompanying lung diseases lead to higher numbers of false-positive (FP) findings [6,7]. Because image quality depends on CT protocol parameters, the CT manufacturer and patient instructions, it can be expected that the performance of a CAD algorithm might differ between institutions. The purpose of this study was therefore to assess whether the performance of a CAD algorithm for acute pulmonary embolism differs in CTPAs acquired at various institutions.     

Obscure gastrointestinal bleeding: diagnostic performance of 64-section multiphase CT enterography and CT angiography compared with capsule endoscopy

Objective:

To compare the diagnostic capabilities between capsule endoscopy (CE) and multislice CT (MSCT) enterography in combination with MSCT angiography for assessment of obscure gastrointestinal bleeding (OGIB).

Methods:

A total of 127 patients with OGIB were looked at in this study. 82 patients (aged 42.7 ± 19.1 years; 34 males) were assigned to receive MSCT diagnosis and 67 patients to (aged 53.9 ± 16.2 years; 28 males) receive CE diagnosis. Among them, 22 patients (aged 54.1 ± 19.1 years; 12 males) received both examinations. Oral isotonic mannitol and intramuscular injection of anisodamine were performed; non-ionic contrast (iopromide, 370 mg I ml⁻¹) was intravenously administered; and then multiphase scanning was conducted at arterial, small intestinal and portal venous phases in MSCT. The results were compared with findings of reference standards including double balloon enteroscopy, digital subtraction angiography, intraoperative pathological examination and/or clinical diagnosis.

Results:

Administration of anisodamine markedly increased the satisfaction rate of bowel filling (94.67% vs 28.57%; p < 0.001) but not the diagnostic yield (p = 0.293) of MSCT. Compared with MSCT, CE showed an improved overall diagnostic yield (68.66% vs 47.56%; p = 0.010), which was also observed in overt bleeding patients (i.e. patients with continued passage of visible blood) (76.19% vs 51.02%; p = 0.013) and in patients aged younger than 40 years of age (85% vs 51.28%; p = 0.024). However, CE had similar positive rates to MSCT (p > 0.05). Among the 22 cases in whom both examinations were conducted, CE showed no significantly different diagnostic capability compared with MSCT (p = 0.4597).

Conclusion:

Both CE and MSCT are safe and effective diagnostic methods for OGIB.

Advances in knowledge:

CE is preferred for overt bleeding or patients aged younger than 40 years. The combined use of CE and MSCT is recommended in OGIB diagnosis.Obscure gastrointestinal bleeding (OGIB), which accounts for approximately 5% of all gastrointestinal haemorrhage cases,¹ is defined as persistent or recurring gastrointestinal bleeding without an obvious aetiology after gastroduodenoscopy and colonoscopy.^2,3 Based on the presence or absence of clinically evident bleeding, OGIB could be divided into occult (no visible blood) and overt (continued passage of visible blood, such as haematemesis, melaena or haematochezia) bleeding.^3,4 OGIB frequently occurs in the small bowel and is caused by small bowel diseases such as intestinal erosions, ulcers, vascular anomaly, gastrointestinal tumours and inflammatory bowel and parasitic diseases.^5,6Multiple diagnostic techniques have been developed to elucidate the causes of OGIB. Among them, two non-invasive technologies, capsule endoscopy (CE) and multislice CT (MSCT) markedly improved the ability to determine the causes of OGIB by allowing the visualization of the gastrointestinal tract.^2,3,6 CE is able to obtain direct visualization of mucosal surface of the entire small intestine.^4,7,8 However, capsule retention remains a major risk of CE diagnosis.^4,9–11 In addition, the visual field restriction limits the value of CE in diagnosis of umbilicate or extraluminal lesions, since the small bowel is difficult to evaluate owing to its large length and tortuous course.^4,10 Conversely, MSCT, including MSCT angiography (MSCTA), MSCT enteroclysis and MSCT enterography (MSCTE), has full capacity to depict the extraintestinal lesions, owing to the combination of the advantages of enteral volume challenge with the ability of cross-sectional imaging.^4,12 Yet, substantial patient radiation exposure is one of the major disadvantages of MSCT diagnosis.^3,13 Careful preparation is also needed before examination.¹⁴ Considering that both CE and MSCT have advantages and disadvantages, a limited number of published data have compared the two diagnostic tools in patients with OGIB.^4,6,15–17 However, most of these studies did not refer to MSCTA, and apparently different results were obtained owing to the advancement of the two technologies. Thus, an updated and comprehensive comparison is required.Hence, we compared the diagnostic capability of MSCTE in combination with MSCTA with CE in patients suffering from OGIB. In this study, MSCTE and MSCTA technologies performed with a 64-slice spiral CT scanner were combined by non-contrast-enhanced scanning after oral administration of a neutral enteric contrast material (isotonic mannitol, 2.5%) and the intramuscular injection of anisodamine to restrain enterocinesia, and the following multiphase scanning at arterial, small intestinal and portal venous phases followed the intravenous infusion of non-ionic iodinated contrast material (iopromide, 370 mg I ml⁻¹). In addition, the influences of the clinical bleeding pattern and age on the diagnostic capability were also investigated.     

Zooming method (× 2.0) of digital mammography vs digital magnification view (× 1.8) in full-field digital mammography for the diagnosis of microcalcifications

The purpose of this study was to determine whether the interpretation of microcalcifications assessed on images zoomed (× 2.0) from digital mammograms is at least equivalent to that from digital magnification mammography (× 1.8) with respect to diagnostic accuracy and image quality. Three radiologists with different levels of experience in mammography reviewed each full-field digital mammography reader set for 185 patients with pathologically proven microcalcification clusters, which consisted of digital magnification mammograms (MAGs) with a magnification factor of 1.8 and images zoomed from mammograms (ZOOM) with a zoom factor of 2.0. Each radiologist rated their suspicion of breast cancer in microcalcific lesions using a six-point scale and the image quality and their confidence in the decisions using a five-point scale. Results were analysed according to display methods using areas under the receiver operating characteristic curves (A_z value) for ZOOM and MAGs to interpret microcalcifications, and the Wilcoxon matched pairs signed rank test for image quality and confidence levels. There was no statistically significant difference in the level of suspicion of breast cancer between the ZOOM and MAG groups (A_z = 0.8680 for ZOOM; A_z = 0.8682 for MAG; p = 0.9897). However, MAG images were significantly better than ZOOM images in terms of visual imaging quality (p < 0.001), and the confidence level with MAG was better than with ZOOM (p < 0.001). In conclusion, the performance of radiologists in the diagnosis of microcalcifications using ZOOM was similar to that using MAGs, although image quality and confidence levels were better using MAGs.Magnification mammography produces better spatial resolution and signal-to-noise ratio than does contact mammography. It is well established as a valuable adjunct to contact mammography, especially for the diagnosis of microcalcifications, despite the additional radiation exposure and increased radiation dose because of the shorter distance between the breast and X-ray source during examination [1–4].However, with respect to full-field digital mammography (FFDM), a few studies using zoomed images from contact mammograms have recently been reported and, as a result, a debate has arisen over whether a digital zooming system of FFDM can replace the magnification view of digital mammography [5–7]. Whereas Fischer et al [5] reported that zoomed images of a digital contact mammogram were equivalent to direct magnification of FFDM for the interpretation of microcalcifications, our previous report suggested that magnification mammography yielded better sensitivity and receiver operating characteristic (ROC) analysis than did zoomed images [7]. However, that study compared images zoomed by a factor of 1.3 with images magnified by a factor of 1.8. Therefore, we wondered whether using a zooming factor comparable to a magnification factor of 1.8 would yield the same results.The purpose of this study was to determine whether the diagnostic accuracy and image quality of microcalcification assessments using images twice zoomed from contact mammograms were equivalent to those obtained using digital magnification mammography by a magnification factor of 1.8.     

Hepatocellular carcinoma in cirrhotic patients at multidetector CT: hepatic venous phase versus delayed phase for the detection of tumour washout

Objectives

Our aim was to compare retrospectively hepatic venous and delayed phase images for the detection of tumour washout during multiphasic multidetector row CT (MDCT) of the liver in patients with hepatocellular carcinoma (HCC).

Methods

30 cirrhotic patients underwent multiphasic MDCT in the 90 days before liver transplantation. MDCT was performed before contrast medium administration and during hepatic arterial hepatic venous and delayed phases, images were obtained at 12, 55 and 120 s after trigger threshold. Two radiologists qualitatively evaluated images for lesion attenuation. Tumour washout was evaluated subjectively and objectively. Tumour-to-liver contrast (TLC) was measured for all pathologically proven HCCs.

Results

48 HCCs were detected at MDCT. 46 of the 48 tumours (96%) appeared as either hyper- or isoattenuating during the hepatic arterial phase subjective washout was present in 15 HCCs (33%) during the hepatic venous phase and in 35 (76%) during the delayed phase (p<0.001, McNemar’s test). Objective washout was present in 30 of the 46 HCCs (65%) during the hepatic venous phase and in 42 of the HCCs (91%) during the delayed phase (p=0.001). The delayed phase yielded significantly higher mean TLC absolute values compared with the hepatic venous phase (−16.1±10.8 HU vs −10.5±10.2 HU; p<0.001).

Conclusions

The delayed phase is superior to the hepatic venous phase for detection of tumour washout of pathologically proven HCC in cirrhotic patients.Multiphasic contrast-enhanced multidetector row CT (MDCT) plays a pivotal role in the diagnostic work-up of cirrhotic patients, who are at increased risk of developing hepatocellular carcinoma (HCC) [1]. Increased enhancement of the tumour compared with the surrounding liver parenchyma during the hepatic arterial phase is the cornerstone for the diagnosis of HCC at multiphasic MDCT [1,2]. However, a variety of entities—dysplastic nodules [3], confluent hepatic fibrosis [4], non-tumourous arterioportal shunts [5] and haemangioma [6]—can also manifest with increased arterial enhancement and thus mimic HCC, particularly if they are smaller than 2 cm in diameter.Tumour washout, i.e. hypoattenuation relative to the adjacent hepatic parenchyma during the hepatic venous or delayed phase, has been recognised as a strong predictor of HCC [7,8]. This sign has been included, along with the presence of hypervascularity, in the latest American Association for the Study of Liver Diseases (AASLD) guidelines for the diagnosis of HCC at multiphasic MDCT, MRI or contrast-enhanced ultrasonography [1]. Although it is well known that tumour enhancement is best visualised during the late hepatic arterial phase [9,10], there is no consensus regarding the correct timing for the detection of tumour washout at multiphasic MDCT of the liver. Most commonly, the hepatic arterial phase is followed by the hepatic venous phase, acquired 60–70 s after injection of contrast material [9-12]. In addition, a delayed phase, acquired from 2–10 min after contrast material injection, can follow the hepatic venous phase [13-20] or can occur alone after the hepatic arterial phase [21-23]. Regardless of the phase sequence chosen, to the best of our knowledge, no study has yet compared the hepatic venous and delayed phases for the detection of tumour washout in patients with HCC. The purpose of our study was to compare retrospectively the hepatic venous and delayed phases for the detection of tumour washout during multiphasic MDCT of the liver in patients with HCC who underwent liver transplantation.     

The many faces of posterior reversible encephalopathy syndrome

The classic imaging findings of posterior reversible encephalopathy syndrome (PRES) are of bilateral parietal and occipital subcortical vasogenic oedema, and are well established in the literature. As experience with PRES grows, varied and atypical presentations are being increasingly described. This pictorial review illustrates the variable presentations of PRES, including cases with atypical imaging findings. We illustrate cases of PRES with varying distributions of vasogenic oedema as well as cases with atypical imaging findings, such as variations of haemorrhage and restricted diffusion. Atypical imaging findings should not dissuade the diagnosis of PRES in the appropriate clinical situation, and knowledge of the varied appearance and atypical findings of PRES allows the radiologist to make this diagnosis.Posterior reversible encephalopathy syndrome (PRES) describes a neurological syndrome characterised by a variety of symptoms, including headache, altered mental status, visual disturbances and seizures, and is accompanied by a unique, potentially reversible imaging pattern [1,2]. Causes of PRES are diverse and include hypertension, eclampsia/pre-eclampsia, sepsis, immunosuppressive agents, chemotherapy, collagen vascular disease and renal failure [2]. Although the pathophysiology of PRES remains unknown, the currently preferred explanation relates to hypertension, impaired autoregulation and hyperperfusion [2]. The classic imaging findings are of vasogenic oedema in the subcortical white matter of the parietal and occipital lobes [3]. As experience with PRES grows in the literature, atypical presentations of PRES are being increasingly described. Authors have demonstrated cases of PRES with atypical vasogenic oedema patterns of distribution, such as frontal lobe, cerebellum, basal ganglia or brain stem involvement [3-6]. Unilateral cases of PRES have also been demonstrated [4]. In addition, cases of PRES with haemorrhage [7] and reversible restricted diffusion [8] have been described. Knowledge of the different presentations of PRES is important, as atypical imaging findings should not dissuade a diagnosis of PRES in the correct clinical context. The purpose of this review is to demonstrate the diverse imaging features of PRES. The cases illustrated in this review demonstrate clinical and imaging presentations characteristic of PRES, with the characteristic clinical and imaging reversibility associated with this diagnosis.     

Clinical dose performance of full field digital mammography in a breast screening programme

Objective

BreastCheck, the Irish Breast Screening Programme, has employed three different models of a full field digital mammography (FFDM) system since its transition to a digital service in 2007. The three models from GE Healthcare, Hologic and Sectra exhibit differences in their design and function, the most significant of which include anode target/filter choice, detector technology and the type of exposure automation.

Methods

The aim of this study was to use the results from a clinical breast dose survey to examine the differences between three different FFDM models in terms of exposure selection, breast mean glandular dose (MGD) and automatic exposure control (AEC) dose contribution.

Results

The accuracy of the dose estimation was improved by inclusion of the AEC pre-exposure dose contribution. The photon-counting system demonstrated the lowest average MGD. The GE Healthcare and Hologic flat-panel detector systems demonstrated a small but statistically significant dose difference. The pre-exposure dose contribution did not exceed 13% of the total exposure dose for any system in the survey. A comparison of the system calculated organ dose estimate from each machine with the corresponding MGD calculated from medical physics measurements indicated reasonably accurate organ dose estimates for most systems in the survey.

Conclusion

The results of this study provide a comprehensive assessment of the breast dose performance of current digital mammography systems in a clinical screening setting.The nationwide expansion of the Irish breast screening programme in 2007 was accompanied by a transition to full field digital mammography (FFDM) technology. Digital mammography could be still considered as a developing technology and experience with digital mammography in breast screening was limited at the time of the change. The advantages associated with digital imaging with respect to workflow efficiency and productivity are well established while the evidence base for clinical benefit associated with improved breast imaging performance through the adoption of digital imaging for mammography continues to grow [1,2]. There are other emerging advantages of digital imaging in breast screening, including the potential for radiation dose reduction [3-5]. Currently available digital mammography systems differ from each other in many ways which can affect the patient dose and can provide system dose advantages. The most significant technical factors in digital mammography systems which impact breast dose include the anode target/filter choice, detector technology and the type of exposure automation. There are also other factors which can affect the dose, including applied breast compression and grid type [6]. A standard feature available on all digital mammography systems is the calculation and display of organ dose estimation. This feature could be a significant factor for the user in the regulation of the patient breast dose.The Irish National Breast Screening Programme, BreastCheck, invites women in the age range 50–64 years to participate in breast cancer screening every 2 years. All women have two views of the breast taken at each visit. Screening is performed in both static screening units and in mobile units, with all reading performed centrally. Three models of FFDM systems, the General Electric (GE, Buc, France) Essential, Hologic Selenia (Danbury, CT) and Sectra MDM L30 (Solna, Sweden), are used in BreastCheck. These systems offer three distinct options of target/filter combination. They also use three distinct detector technologies: flat-panel phosphor, selenium flat-panel and photon counting. The ongoing development of digital mammography has been accompanied by optimisation of the X-ray beam and detector technology towards minimising breast dose and optimising image quality [7,8]. The imaging systems used in BreastCheck also employ different approaches to automation of exposures. The type of automation varies depending on the design and purpose of the control. In two models the detector is used as the automatic exposure control (AEC) sensor, which necessitates a pre-exposure, as detector operation entails separate acquisition and image-read phases [9]. This approach differs to that used by the photon-counting detector system, which permits instantaneous AEC sensor operation during image acquisition using the leading edge detector [10]. The aim of the automated control is to regulate the signal-to-noise ratio (SNR) or contrast-to-noise ratio (CNR) and, depending on the system design, to ensure the radiation intensities do not exceed the capacity of the detector [9,10].Compliance with the European Directive on health protection of individuals against the dangers of ionising radiation in relation to medical exposures 97/43/EURATOM [11] requires that all X-ray units are subject to a patient dose survey at regular intervals. This is emphasised for screening programmes, where the majority of the invited population are asymptomatic. The use of digital imaging offers the advantage that many aspects of the data collection and processing can be automated [12]. The aim of this study was to exploit the results from a comprehensive clinical breast dose survey to examine the differences between three different FFDM models in terms of exposure selection, breast mean glandular dose (MGD) and AEC dose contribution. A comparison of the organ dose estimate from each machine with the corresponding dose calculated by medical physics measurements was also performed.     

Focal nodular hyperplasia: characterisation at gadoxetic acid-enhanced MRI and diffusion-weighted MRI

Purpose:

The aim of this study was to assess the enhancement patterns of hepatic focal nodular hyperplasia (FNH) on gadoxetic acid-enhanced MRI and diffusion-weighted (DW) MRI.

Methods:

This retrospective study had institutional review board approval. Gadoxetic acid-enhanced and DW MR images were evaluated in 23 patients with 30 FNHs (26 histologically proven and 4 radiologically diagnosed). The lesion enhancement patterns of the hepatobiliary phase images were classified as heterogeneous or homogeneous signal intensity (SI), and as dominantly high/iso or low SI compared with those of adjacent liver parenchyma. Heterogeneous (any) SI lesions and homogeneous low SI lesions were categorised into the fibrosis group, whereas homogeneous high/iso SI lesions were categorised into the non-fibrosis group. Additionally, lesion SI on T₂ weighted images, DW images and apparent diffusion coefficient (ADC) values were compared between the two groups.

Results:

The lesions showed heterogeneous high/iso SI (n=16), heterogeneous low SI (n=5), homogeneous high/iso SI (n=7) or homogeneous low SI (n=2) at the hepatobiliary phase MR images. The fibrosis group lesions were more likely to show high SI on DW images and T₂ weighted images compared with those in the non-fibrosis group (p<0.05). ADC values tended to be lower in the fibrosis group than those in the non-fibrosis group without significance.

Conclusion:

FNH showed variable enhancement patterns on hepatobiliary phase images during gadoxetic acid-enhanced MRI. SI on DW and T₂ weighted images differed according to the fibrosis component contained in the lesion.

Advances in knowledge:

FNH shows a wide spectrum of imaging findings on gadoxetic acid-enhanced MRI and DW MRI.Focal nodular hyperplasia (FNH) is the second most common benign hepatic tumour after haemangioma, and most frequently occurs in females of childbearing and middle age [1]. It is considered to result from a congenital vascular disorder leading to a hyperplastic response of the surrounding liver parenchyma and is histologically characterised by normal hepatocytes with malformed bile ducts [2,3]. It is generally accepted that FNH can be managed conservatively and most cases do not require surgery because of the lack of malignancy potential and low risk of complications such as rupture or haemorrhage [4,5]. Therefore, the goal of imaging is to make a confident diagnosis and to avoid a biopsy or even surgical resection.MRI is a well-established and widely used diagnostic modality for detecting and characterising focal hepatic lesions and generally allows a confident diagnosis of typical FNH [6–8]. Findings of typical FNH on conventional gadolinium-enhanced MRI are brisk arterial enhancement, iso or slightly low signal intensity (SI) on the portal and equilibrium phase, iso or slightly low SI on T₁ weighted images, iso or slightly high SI on T₂ weighted images, a central scar showing high SI on T₂ weighted images and delayed dynamic enhancement [6–9]. However, when atypical imaging features are present, such as atypical findings of a central scar, high SI on T₁ weighted images or washout during the portal or equilibrium phase, it is not easy to distinguish FNH from other hypervascular tumours, such as hepatocellular adenomas, hypervascular metastasis or fibrolamellar hepatocellular carcinomas [6,9]. Indeed, according to a study by Bieze et al [6], characterisation of FNH and hepatocellular adenoma on standard MRI is inconclusive in 40% of lesions.Gadoxetic acid (Primovist®; Bayer-Schering Pharma, Berlin, Germany) is a new recently approved hepatobiliary gadolinium-based contrast agent. It has dual pharmacokinetic actions that combine extracellular properties for dynamic phase imaging with high hepatocyte-specific uptake and biliary excretion for delayed hepatobiliary phase imaging [10,11]. Many reports have concluded that FNHs show liver-specific enhancement and appear as iso or high SI on hepatobiliary phase imaging, and this enhancement pattern is a new additional criterion for diagnosing FNH, particularly in comparison with hepatocellular adenoma [6,10–15]. However, even though the major enhancement features of FNH are iso or high SI on hepatobiliary phase imaging, the portion of the central stellate scar or radiating fibrous septa of FNH demonstrates low SI owing to a lack of functioning hepatocytes. We postulate that the overall SI of FNH lesions during hepatobiliary phase imaging is dependent on their proportions of cellular and fibrous components.Diffusion-weighted (DW) imaging is useful for the detection and characterisation of hepatic focal lesions [16–18]. In theory, DW imaging measures the random motion of water molecules in biological tissues and reflects tissue properties, such as the size of the extracellular space, viscosity and cellularity [18–20]. According to prior hepatic fibrosis evaluations using DW imaging, lower apparent diffusion coefficient (ADC) values are observed in cirrhotic liver compared with normal liver tissue, which may be owing to restricted diffusion from extracellular fibrosis [21–25]. Despite the fact that FNH is benign, some lesions show diffusion restrictions, probably owing to their high cellularity [26–28], and fibrosis components contained in FNH lesions should influence the degree of diffusion restriction.The purpose of this study was to classify FNH lesions according to their enhancement pattern on hepatobiliary phase imaging and to assess the findings on DW and T₂ weighted imaging of the lesions with regard to those on hepatobiliary phase imaging.     

Use of 99mTc-doxorubicin scintigraphy in females with breast cancer: a pilot study

Objective:

Doxorubicin (Eurofarma, São Paulo, Brazil) is an antitumour agent widely used in the treatment of breast cancer and can be used for tumour tracking when labelled with a radionuclide. Here, we present the results obtained with technetium-99m (^99mTc)-doxorubicin, using the direct method, to evaluate its uptake in breast cancer.

Methods:

Four females with confirmed breast carcinoma diagnosis and breast image reporting and data system Category 5 on mammography underwent whole-body and thorax single-photon emission CT/CT imaging 1 and 3 h after ^99mTc-doxorubicin administration.

Results:

We observed increased uptake in breast carcinoma lesions and elimination via renal and hepatic pathways.

Conclusion:

These preliminary results suggest that ^99mTc-doxorubicin may be a promising radiopharmaceutical for the evaluation of patients with breast cancer. Further studies are ongoing.

Advances in knowledge:

To our knowledge, this is the first study to evaluate the use of a directly labelled doxorubicin tracer in humans. ^99mTc-doxorubicin could provide information on the response of tumours to doxorubicin.Breast cancer is the most common cancer in females worldwide, with an estimated 1.67 million new cases in 2012.¹ In order to improve the treatment and prognosis of breast cancer, early detection is extremely important. However, the techniques most often used for cancer evaluation, such as mammography, ultrasonography and MRI, have limitations and are not always capable of differentiating benign from malignant lesions. Breast scintigraphy has some clinical indications and, in association with other imaging methods, can increase the accuracy of diagnoses and reduce unnecessary biopsies.²Advances in imaging modalities have contributed to the improvement of early breast cancer diagnosis.³ The use of positron emission tomography (PET) and its new radiopharmaceuticals is an important advance in cancer detection.⁴ Hybrid acquisition of PET with CT (PET/CT) allows evaluation of morphological parameters, increasing the sensitivity and specificity of PET findings.⁴ However, the uptake of fluorine-18-fludeoxyglucose (¹⁸F-FDG), the radiopharmaceutical most often used for PET, changes according to different variables, such as the histological type. In breast cancer, infiltrating ductal carcinoma shows higher uptake than infiltrating lobular carcinoma, while in ductal carcinoma, uptake is usually low.^{5–7 18}F-FDG uptake also depends on the grade of breast cancer.^6,8 Hybrid PET/CT has low sensitivity for tumours <1 cm, owing to limitations in spatial resolution and tumour variables,^7,8 and ¹⁸F-FDG uptake may occur in benign lesions such as inflammatory granulomatous mastitis.⁹ Although PET/CT is limited in the evaluation of tumour size and the presence of multifocal disease, this might change with the advent of positron emission mammography (PEM). Eo et al¹⁰ reported that PEM diagnosed more malignant breast lesions than PET/CT, particularly in tumours <2 cm.Unfortunately, PET scanners are not available in all nuclear medicine services, notably in developing countries. Conventional gamma cameras, on the other hand, are widely available and therefore single-photon emission CT (SPECT) radiopharmaceuticals have the potential to benefit a larger number of patients. Another promising tool is the use of dedicated apparatus for conventional nuclear medicine of the breast, called molecular breast imaging (MBI), which can detect malignant breast lesions <1 cm.^11,12Doxorubicin (Eurofarma, São Paulo, Brazil) is a potent antitumour agent that is widely used in chemotherapy for several types of cancer.¹³ It acts by intercalating nucleotide bases, binding to the lipid membrane, and also inhibits the biosynthesis of macromolecules.¹⁴ Among the main side effects of this drug is possible cardiotoxicity.¹⁵ Technetium-99m (^99mTc) is the radionuclide most often used in conventional nuclear medicine; our research group has used ^99mTc to radiolabel different types of cells and molecules.^16–23 We previously reported a technique for labelling the thymidine precursor thymine with ^99mTc, with good specificity and high predictive value.^16–18 We have also used ^99mTc-doxorubicin in dogs and cats in order to evaluate its uptake in different kinds of tumours, with promising results, which led to the approval of this pilot trial.²⁴