Multiparametric MRI guidance in first-time prostate biopsies: what is the real benefit?

PURPOSE

With the increased recognition of the capabilities of prostate multiparametric (mp) magnetic resonance imaging (MRI), attempts are being made to incorporate MRI into routine prostate biopsies. In this study, we aimed to analyze the diagnostic yield via cognitive fusion, transrectal ultrasound (TRUS)-guided, and in-bore MRI-guided biopsies in biopsy-naive patients with positive findings for prostate cancer screening.

METHODS

Charts of 140 patients, who underwent transrectal prostate biopsy after the adaptation of mp-MRI into our routine clinical practice, were reviewed retrospectively. Patients with previous negative biopsies (n=24) and digital rectal examination findings suspicious for ≥cT3 prostate cancer (n=16) were excluded. T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast-enhanced imaging were included in mp-MRI. Cognitive fusion biopsies were performed after a review of mp-MRI data, whereas TRUS-guided biopsies were performed blinded to MRI information. In-bore biopsies were conducted by means of real-time targeting under MRI guidance.

RESULTS

Between January 2012 and February 2014, a total of 100 patients fulfilling the inclusion criteria underwent TRUS-guided (n=37), cognitive fusion (n=49), and in-bore (n=14) biopsies. Mean age, serum prostate specific antigen level, and prostate size did not differ significantly among the study groups. In TRUS-guided biopsy group, 51.3% were diagnosed with prostate cancer, while the same ratio was 55.1% and 71.4% in cognitive fusion and in-bore biopsy groups, respectively (P = 0.429). Clinically significant prostate cancer detection rate was 69.1%, 70.3%, and 90% in TRUS-guided, cognitive fusion, and in-bore biopsy groups, respectively (P = 0.31). According to histopathologic variables in the prostatectomy specimen, significant prostate cancer was detected in 85.7%, 93.3%, and 100% of patients in TRUS-guided, cognitive fusion, and in-bore biopsy groups, respectively.

CONCLUSION

In the first set of transrectal prostate biopsies, mp-MRI guidance did not increase the diagnostic yield significantly.Transrectal ultrasound-guided prostate biopsy (TRUS-guided) to diagnose prostate cancer is currently estimated to be performed in one million men annually in the USA (1). The original random systematic, six-core transrectal prostate biopsy, initially described by Stamey in 1989 (2), has incorporated more cores over time, with laterally directed 12–14 cores being an accepted practice standard. The major limitation of random systematic sampling is that; clinically insignificant cancers are often identified by chance and affect survival data due to lead and length time bias from overdetection and overtreatment of indolent disease (3). Unlike the diagnostic pathways for other organ cancers, which include direct visual or radiologic guidance, the prostate is being sampled by way of standardized, systematic but essentially random approaches.With the aid of multiparametric MRI of the prostate (mp-MRI), clinically relevant localized prostate cancer foci may be identified, selectively sampled, and treated (4–6). Hence attempts are being made to incorporate mp-MRI into routine prostate biopsies. Techniques of MRI-targeted biopsy include visual estimation TRUS-guided biopsy (cognitive fusion); software co-registered MRI-ultrasound TRUS-guided biopsy; and in-bore MRI-guided biopsy.MRI-guided prostate biopsies are particularly useful in the setting of ongoing clinical suspicion of prostate cancer despite previous negative biopsies. Among men with a previous negative biopsy, 72% to 87% of cancers detected by MRI-guidance are clinically significant (7). Likewise, mp-MRI findings can also be utilized to cognitively tailor the initial transrectal prostate biopsy protocol. Among men with no previous biopsy, MRI increases the frequency of significant cancer detection to 50% in low risk and 71% in high risk patients (7).In this study, we aimed to compare the diagnostic efficiency of cognitive fusion, TRUS-guided and in-bore biopsies, which were conducted as the initial sampling modality, in terms of detecting clinically significant prostate cancer.     

Negative predictive value of multiparametric MRI for prostate cancer detection: Outcome of 5-year follow-up in men with negative findings on initial MRI studies

Objective

To assess the clinical negative predictive value (NPV) of multiparametric MRI (mp-MRI) for prostate cancer in a 5-year follow-up.

Materials and methods

One hundred ninety-three men suspected of harboring prostate cancer with negative MRI findings were included. Patients with positive transrectal ultrasound (TRUS)-guided biopsy findings were defined as false-negative. Patients with negative initial TRUS-guided biopsy findings were followed up and only patients with negative findings by digital rectal examination, MRI, and repeat biopsy and no increase in PSA at 5-year follow-up were defined as “clinically negative”. The clinical NPV of mp-MRI was calculated. For quantitative analysis, mean signal intensity on T2-weighted images and the mean apparent diffusion coefficient value on ADC maps of the initial MRI studies were compared between peripheral-zone (PZ) cancer and the normal PZ based on pathologic maps of patients who had undergone radical prostatectomy.

Results

The clinical NPV of mp-MRI was 89.6% for significant prostate cancer. Small cancers, prostatitis, and benign prostatic hypertrophy masking prostate cancer returned false-negative results. Quantitative analysis showed that there was no significant difference between PZ cancer and the normal PZ.

Conclusion

The mp-MRI revealed a high clinical NPV and is a useful tool to rule out clinically significant prostate cancer before biopsy.     

MR-sequences for prostate cancer diagnostics: validation based on the PI-RADS scoring system and targeted MR-guided in-bore biopsy

Purpose

This study evaluated the accuracy of MR sequences [T2-, diffusion-weighted, and dynamic contrast-enhanced (T2WI, DWI, and DCE) imaging] at 3T, based on the European Society of Urogenital Radiology (ESUR) scoring system [Prostate Imaging Reporting and Data System (PI-RADS)] using MR-guided in-bore prostate biopsies as reference standard.

Methods

In 235 consecutive patients [aged 65.7?±?7.9 years; median prostate-specific antigen (PSA) 8 ng/ml] with multiparametric prostate MRI (mp-MRI), 566 lesions were scored according to PI-RADS. Histology of all lesions was obtained by targeted MR-guided in-bore biopsy.

Results

In 200 lesions, biopsy revealed prostate cancer (PCa). The area under the curve (AUC) for cancer detection was 0.70 (T2WI), 0.80 (DWI), and 0.74 (DCE). A combination of T2WI + DWI, T2WI + DCE, and DWI + DCE achieved an AUC of 0.81, 0.78, and 0.79. A summed PI-RADS score of T2WI + DWI + DCE achieved an AUC of 0.81. For higher grade PCa (primary Gleason pattern?≥?4), the AUC was 0.85 for T2WI + DWI, 0.84 for T2WI + DCE, 0.86 for DWI + DCE, and 0.87 for T2WI + DWI + DCE. The AUC for T2WI + DWI + DCE for transitional-zone PCa was 0.73, and for the peripheral zone 0.88. Regarding higher-grade PCa, AUC for transitional-zone PCa was 0.88, and for peripheral zone 0.96.

Conclusion

The combination of T2WI + DWI + DCE achieved the highest test accuracy, especially in patients with higher-grade PCa. The use of ≤2 MR sequences led to lower AUC in higher-grade and peripheral-zone cancers.

Key Points

? T2WI + DWI + DCE achieved the highest accuracy in patients with higher grade PCa ? T2WI + DWI + DCE was more accurate for peripheral- than for transitional-zone PCa ? DCE increased PCa detection accuracy in the peripheral zone ? DWI was the leading sequence in the transitional zone     

Imaging and pathology findings after an initial negative MRI-US fusion-guided and 12-core extended sextant prostate biopsy session

PURPOSE

A magnetic resonance imaging-ultrasonography (MRI-US) fusion-guided prostate biopsy increases detection rates compared to an extended sextant biopsy. The imaging characteristics and pathology outcomes of subsequent biopsies in patients with initially negative MRI-US fusion biopsies are described in this study.

MATERIALS AND METHODS

We reviewed 855 biopsy sessions of 751 patients (June 2007 to March 2013). The fusion biopsy consisted of two cores per lesion identified on multiparametric MRI (mpMRI) and a 12-core extended sextant transrectal US (TRUS) biopsy. Inclusion criteria were at least two fusion biopsy sessions, with a negative first biopsy and mpMRI before each.

RESULTS

The detection rate on the initial fusion biopsy was 55.3%; 336 patients had negative findings. Forty-one patients had follow-up fusion biopsies, but only 34 of these were preceded by a repeat mpMRI. The median interval between biopsies was 15 months. Fourteen patients (41%) were positive for cancer on the repeat MRI-US fusion biopsy. Age, prostate-specific antigen (PSA), prostate volume, PSA density, digital rectal exam findings, lesion diameter, and changes on imaging were comparable between patients with negative and positive rebiopsies. Of the patients with positive rebiopsies, 79% had a positive TRUS biopsy before referral (P = 0.004). Ten patients had Gleason 3+3 disease, three had 3+4 disease, and one had 4+4 disease.

CONCLUSION

In patients with a negative MRI-US fusion prostate biopsy and indications for repeat biopsy, the detection rate of the follow-up sessions was lower than the initial detection rate. Of the prostate cancers subsequently found, 93% were low grade (≤3+4). In this low risk group of patients, increasing the follow-up time interval should be considered in the appropriate clinical setting.Prostate cancer is the most common cancer in males, with an estimated 238 590 new diagnoses annually in the USA, and it is the second leading cause of cancer-related mortality in males (1). One in six males will develop prostate cancer in his lifetime (1). The current standard of care for diagnosing and grading prostate cancer is a 12-core extended sextant biopsy obtained with transrectal ultrasonography (TRUS) guidance (2, 3). As magnetic resonance imaging (MRI) has superior contrast resolution than ultrasonography (US), it is possible for multiparametric MRI (mpMRI) to detect prostate cancer with high reliability (4). Since clinically insignificant cancer is often invisible to magnetic resonance (MR), prostate MRI preferentially detects more aggressive cancers (5–9). MRI can be used to guide the prostate biopsy, either using a direct “in-gantry” approach or by using MRI-US fusion, which was developed as an office-based alternative (10). MRI-US targeted biopsies have about twice the per-core detection rate of sextant biopsies (11), and have been shown to be particularly useful for prostates measuring greater than 40 mL, which typically have lower rates of cancer detection than smaller prostate glands (12).Since TRUS-guided biopsies have a relatively low sensitivity, many patients with a rising prostate-specific antigen (PSA), but an initial negative biopsy, undergo additional biopsies with progressively lower yields. In a study of sequential systematic biopsies in 1051 males, the detection rate of successive biopsies was 22%, 10%, 5%, and 4%, respectively (13). The third and fourth TRUS-guided biopsy sessions detected lower grade cancers and were found to have higher morbidity than the first two biopsies. Recently, MRI-US fusion biopsy has been reported to increase cancer detection rates in the setting of a prior negative TRUS biopsy (14, 15).While MRI-US fusion biopsy is promising in the setting of previous negative random sampling, the response to a negative MRI-US fusion biopsy is less clear. Since a MRI-US fusion biopsy increases prostate cancer detection, this population should have a lower disease burden than patients with an initial negative TRUS-guided biopsy alone. Now that MRI-US fusion biopsies have been available for several years, such data are beginning to accumulate. Here, we investigate the detection rates of subsequent biopsies in patients with an initial negative MRI-US fusion prostate biopsy.     

Analysis of histological findings obtained combining US/mp-MRI fusion-guided biopsies with systematic US biopsies: mp-MRI role in prostate cancer detection and false negative

Aims and objectives

To evaluate the diagnostic accuracy of mp-MRI correlating US/mp-MRI fusion-guided biopsy with systematic random US-guided biopsy in prostate cancer diagnosis.

Materials and methods

137 suspected prostatic abnormalities were identified on mp-MRI (1.5T) in 96 patients and classified according to PI-RADS score v2. All target lesions underwent US/mp-MRI fusion biopsy and prostatic sampling was completed by US-guided systematic random 12-core biopsies. Histological analysis and Gleason score were established for all the samples, both target lesions defined by mp-MRI, and random biopsies. PI-RADS score was correlated with the histological results, divided in three groups (benign tissue, atypia and carcinoma) and with Gleason groups, divided in four categories considering the new Grading system of the ISUP 2014, using t test. Multivariate analysis was used to correlate PI-RADS and Gleason categories to PSA level and abnormalities axial diameter. When the random core biopsies showed carcinoma (mp-MRI false-negatives), PSA value and lesions Gleason median value were compared with those of carcinomas identified by mp-MRI (true-positives), using t test.

Results

There was statistically significant difference between PI-RADS score in carcinoma, atypia and benign lesions groups (4.41, 3.61 and 3.24, respectively) and between PI-RADS score in Gleason < 7 group and Gleason > 7 group (4.14 and 4.79, respectively). mp-MRI performance was more accurate for lesions > 15 mm and in patients with PSA > 6 ng/ml. In systematic sampling, 130 (11.25%) mp-MRI false-negative were identified. There was no statistic difference in Gleason median value (7.0 vs 7.06) between this group and the mp-MRI true-positives, but a significant lower PSA median value was demonstrated (7.08 vs 7.53 ng/ml).

Conclusion

mp-MRI remains the imaging modality of choice to identify PCa lesions. Integrating US-guided random sampling with US/mp-MRI fusion target lesions sampling, 3.49% of false-negative were identified.

     

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.     

Incremental diagnostic value of targeted biopsy using mpMRI-TRUS fusion <Emphasis Type="Italic">versus</Emphasis> 14-fragments prostatic biopsy: a prospective controlled study

Objectives

To compare the incremental diagnostic value of targeted biopsy using real-time multiparametric magnetic resonance imaging and transrectal ultrasound (mpMRI-TRUS) fusion to conventional 14-cores biopsy.

Patients and Methods

Uni-institutional, institutional review board (IRB) approved prospective blinded study comparing TRUS-guided random and targeted biopsy using mpMRI-TRUS fusion, in 100 consecutive men. We included men with clinical-laboratorial suspicious for prostate cancer and Likert score ≥ 3 mp-MRI. Patients previously diagnosed with prostate cancer were excluded. All patients were submitted to 14-cores TRUS-guided biopsy (mpMRI data operator-blinded), followed by targeted biopsy using mpMRI-TRUS fusion.

Results

There was an overall increase in cancer detection rate, from 56% with random technique to 62% combining targeted biopsy using mpMRI-TRUS fusion; incremental diagnosis was even more relevant for clinically significant lesions (Gleason ≥ 7), diagnosing 10% more clinically significant lesions with fusion biopsy technique. Diagnosis upgrade occurred in 5 patients that would have negative results in random biopsies and had clinically significant tumours with the combined technique, and in 5 patients who had the diagnosis of significant tumours after fusion biopsy and clinically insignificant tumours in random biopsies(p=0.0010).

Conclusions

Targeted biopsy using mpMRI-TRUS fusion has incremental diagnostic value in comparison to conventional random biopsy, better detecting clinically significant prostate cancers.

Key Points

? mpMRI-TRUS targeted biopsy increases overall cancer detection rate, but not statistically significant.? mpMRI-TRUS targeted biopsy actually improves the diagnosis of clinically significant PCa.? There was no evidence to acquire the mpMRI-TRUS fusion cores alone.

     

Diagnosing common parotid tumours with magnetic resonance imaging including diffusion-weighted imaging vs fine-needle aspiration cytology: a comparative study

Objectives

The purpose of this study was to evaluate the accuracy of MRI combined with diffusion-weighted imaging (DWI) vs fine-needle aspiration cytology (FNAC) in diagnosing common parotid masses.

Methods

25 consecutive patients (mean age 61 years) with parotid masses were included in this study. Informed consent and ethical approval was obtained. 22 patients underwent both MRI combined with DWI and FNAC. From DWI data, apparent diffusion coefficient maps were generated. The MRI study protocol consisted of T₁ weighted spin echo; T₂ weighted and T₂ weighted fat-suppressed turbo spin echo; DWI; and T₁ weighted fat-suppressed post-contrast images. MRI and FNAC diagnoses were compared with histopathology. Youden''s index was used to compare the two methods.

Results

Masses comprised eight Warthin tumours, eight adenomas (six pleomorphic adenomas, two basal cell adenomas), five carcinomas, two lipomas, one haemagioma and one benign lymphadenopathy. Technically, MRI was successful in 24 of the 25 patients (96%), FNAC was successful in 20 of the 23 patients (87.0%). The accuracy, sensitivity and specificity of MRI without DWI were 96%, 80% and 100%, respectively. Diagnostic accuracy did not increase by adding DWI to conventional MRI; however, DWI was helpful for diagnosing benign tumour histology. MRI combined with DWI was successful for determining accurate tumour typing in all benign masses except one lymphadenopathy. When FNAC had adequate material the accuracy, sensitivity and specificity were 95%, 75% and 100%, respectively. Youden''s index was 0.80 for MRI and 0.75 for FNAC.

Conclusions

MRI combined with DWI seems to have similar diagnostic potential as FNAC in differentiation of benign vs malignant parotid masses.     

Role of diffusion-weighted magnetic resonance imaging in the evaluation of hepatocellular carcinoma response to transcatheter arterial chemoembolization using drug eluting beads; correlation with dynamic MRI

Aim

To evaluate accuracy of DWI in evaluating HCC response to DEB TACE and compare the results with DCE MRI.

Classification of Focal Prostatic Lesions on Transrectal Ultrasound (TRUS) and the Accuracy of TRUS to Diagnose Prostate Cancer

Objective

To improve the diagnostic efficacy of transrectal ultrasound (TRUS)-guided targeted prostatic biopsies, we have suggested the use of a new scoring system for the prediction of malignancies regarding the characteristics of focal suspicious lesions as depicted on TRUS.

Materials and Methods

A total of 350 consecutive patients with or without prostate cancer who underwent targeted biopsies for 358 lesions were included in the study. The data obtained from participants were randomized into two groups; the training set (n = 240) and the test set (n = 118). The characteristics of focal suspicious lesions were evaluated for the training set and the correlation between TRUS findings and the presence of a malignancy was analyzed. Multiple logistic regression analysis was used to identify variables capable of predicting prostatic cancer. A scoring system that used a 5-point scale for better malignancy prediction was determined from the training set. Positive predictive values for malignancy prediction and the diagnostic accuracy of the scored components with the use of receiver operating characteristic curve analysis were evaluated by test set analyses.

Results

Subsequent multiple logistic regression analysis determined that shape, margin irregularity, and vascularity were factors significantly and independently associated with the presence of a malignancy. Based on the use of the scoring system for malignancy prediction derived from the significant TRUS findings and the interactions of characteristics, a positive predictive value of 80% was achieved for a score of 4 when applied to the test set. The area under the receiver operating characteristic curve (AUC) for the overall lesion score was 0.81.

Conclusion

We have demonstrated that a scoring system for malignancy prediction developed for the characteristics of focal suspicious lesions as depicted on TRUS can help predict the outcome of TRUS-guided biopsies.     

Bone metastases from prostate, breast and multiple myeloma: differences in lesion conspicuity at short-tau inversion recovery and diffusion-weighted MRI

Objectives

The objective of this study was to compare the relative conspicuity of bone metastases on short-tau inversion recovery (STIR) and diffusion-weighted MRI (DWI) whole-body MR sequences for breast, prostate and myeloma malignancies.

Methods

44 whole-body MRI scans were reviewed retrospectively (coronal T₁ weighted, STIR and DWI with b=800). On each scan, up to four of the largest bone lesions were identified on T₁ weighting, and the region of interest signal intensity was measured on STIR and DWI, as well as the background signal intensity. The mean lesion signal to background ratio was calculated for each patient and then for each malignancy group.

Results

In prostate cancer patients, the DWI signal/background ratio was greater than that of STIR in 22 out of 24 patients (mean DWI lesion/background ratio 3.91, mean STIR lesion/background ratio 2.31; p=0.0001). In multiple myeloma, the DWI ratio was higher in 6/7 patients (DWI group mean ratio 7.59, STIR group mean ratio 3.7; p=0.0366). In 13 breast cancer patients, mean STIR and DWI signal/background were similar (DWI group mean ratio 4.13, group mean STIR ratio 4.26; p=0.8587).

Conclusion

Bone lesion conspicuity measured by lesion/background signal intensity was higher on DWI b=800 than on STIR in patients with prostate cancer and multiple myeloma. DWI should be used in whole-body MR oncology protocols in these conditions to maximise lesion detection.Metastatic disease to bones can be the only site of distant spread in patients with prostate or breast cancer. Accurate detection of such disease dissemination can be challenging as small-volume disease confined to the marrow cavity may be missed on radionuclear bone scintigraphy or CT imaging. Whole-body (WB) MRI is increasingly used in oncological imaging as a tool to improve detection of bone metastases. Several authors report good results compared with other modalites. Baur-Melnyk et al [1] found WB MRI gave superior detection rate and staging for myeloma compared with CT, and Shortt et al [2], evaluating the same malignancy, concluded that WB MRI performed better than positron emission tomography CT. In prostate and breast patients, Gutzeit et al [3] found WB MRI to rank equally with skeletal scintigraphy for detection of bone lesions, and in some cases detected markedly more metastases. In a recent pooled meta-analysis of published studies, WB MRI showed a pooled sensitivity of 90.0% and pooled specificity of 91.8% for the detection of bone metastases [4].WB MRI imaging protocols have evolved with time as MRI scanners are now more technologically advanced. Conventional WB MRI studies have typically employed T₁ weighted (T₁W) and short-tau inversion recovery (STIR) sequences [1,5,6]. However, more recently, diffusion-weighted sequences are increasingly being utilised [3,7]. The image contrast from diffusion-weighted MRI (DWI) is based on difference in the mobility of water protons between tissues. As the mobility of water protons is impeded more in tumour than in normal tissues, this results in higher signal intensity returned from tumour tissues on DWI. Nakanishi et al [8] found that adding DWI to T₁ and STIR sequences improved the sensitivity and positive predictive value for detecting bone metastases in a variety of tumour types.Although WB MRI using combinations of T₁W, STIR and DWI sequences is being applied in clinical practice, it is unclear to what degree DWI improves lesion detection compared with the more widely applied STIR imaging. Clearly, a high lesion-to-background contrast ratio would improve lesion conspicuity and detectability. Hence, the purpose of this study was to determine the relative conspicuity of bone lesions with STIR and DWI sequences for breast, prostate and myeloma malignancies.     

Detection of prostate cancer with three-dimensional transrectal ultrasound: correlation with biopsy results

Objectives

The aim of this study was to evaluate the role of three-dimensional transrectal ultrasound in the diagnosis of prostate cancer.

Methods

A total of 112 patients with elevated serum prostate-specific antigen (PSA) or a positive digital rectal examination were evaluated using three-dimensional greyscale transrectal ultrasound (3D-GS TRUS) and three-dimensional power Doppler sonography (3D-PDS). Target biopsies were obtained together with 12 core systematic biopsies. Pathological results were correlated with the imaging data.

Results

Cancers were detected in 269 biopsy sites from 41 patients. 229 sites of cancer were depicted by 3D-GS TRUS and 213 sites were depicted by 3D-PDS. 30 sites were missed by both 3D-GS TRUS and 3D-PDS. Abnormal prostate images depicted by 3D-GS TRUS and 3D-PDS were associated with lesions with a Gleason score of 6.9 or higher.

Conclusion

The detection rates of prostate cancer were significantly improved with 3D-GS TRUS and 3D-PDS on serum PSA levels >10 ng ml^–1 or 20 ng ml^–1. 3D-GS TRUS and 3D-PDS may improve the biopsy yield by determining appropriate sites for target and systematic biopsies. The abnormalities detected by 3D ultrasound were associated with moderate- and high-grade prostate cancers. However, based on the number of false-negative TRUS results, the use of systematic prostate biopsies should not be eliminated.Prostate cancer is a common malignancy in older males. Previous autopsy studies have shown that one-third of males over 50 years old have latent cancer, yet only 10% develop clinically significant carcinomas during their lifetime [1]. The exact mechanism mediating the progression of microfocal cancers into symptomatic forms of the disease has not been elucidated. Since prostate cancers demonstrate remarkably heterogeneous behaviours ranging from slow-growing lesions to aggressive tumours that metastasise rapidly [2], the diagnosis and treatment of prostate cancers is very challenging. The current methods of screening for prostate cancer include measuring serum prostate-specific antigen (PSA) levels, digital rectal examination and transrectal ultrasound (TRUS) scanning and biopsy. However, controversy surrounds which screening method is the most clinically significant for detecting lesions.Since approximately 20–50% of prostate cancers are invisible by greyscale (GS) TRUS [3], GS TRUS has limited value for detection of prostate cancer [4,5]. In addition, 35% of lesions missed by GS TRUS are moderate- or high-grade tumours [6]. Colour Doppler ultrasound, as an important adjunct to GS TRUS, could improve detection of prostate cancer, although in one study 16% of cases with clinically significant cancer were still missed by this method [7].Three-dimensional (3D) TRUS is a relatively new imaging modality. Preliminary studies have shown improved cancer detection with 3D TRUS when compared with two-dimensional TRUS [8,9]. However, it is still unknown which malignant lesions may be detected by 3D TRUS. Furthermore, 3D TRUS has not been analysed in correlation with the site-specific biopsy pathological results.The purpose of this study was to assess the role of 3D-GS TRUS and 3D power Doppler sonography (3D-PDS) in the diagnosis of prostate carcinoma. This study correlated 3D-GS TRUS and 3D-PDS data with biopsy pathological results using a site-by-site analysis that included target and systematic biopsies.     

Added value of diffusion-weighted MRI in detection of cervical cancer recurrence: comparison with morphologic and dynamic contrast-enhanced MRI sequences

PURPOSE

We aimed to evaluate the added value of diffusion-weighted imaging (DWI) to standard magnetic resonance imaging (MRI) for detecting post-treatment cervical cancer recurrence. The detection accuracy of T2-weighted (T2W) images was compared with that of T2W MRI combined with either dynamic contrast-enhanced (DCE) MRI or DWI.

METHODS

Thirty-eight women with clinically suspected uterine cervical cancer recurrence more than six months after treatment completion were examined with 1.5 Tesla MRI including T2W, DCE, and DWI sequences. Disease was confirmed histologically and correlated with MRI findings. The diagnostic performance of T2W imaging and its combination with either DCE or DWI were analyzed. Sensitivity, positive predictive value, and accuracy were calculated.

RESULTS

Thirty-six women had histologically proven recurrence. The accuracy for recurrence detection was 80% with T2W/DCE MRI and 92.1% with T2W/DWI. The addition of DCE sequences did not significantly improve the diagnostic ability of T2W imaging, and this sequence combination misclassified two patients as falsely positive and seven as falsely negative. The T2W/DWI combination revealed a positive predictive value of 100% and only three false negatives.

CONCLUSION

The addition of DWI to T2W sequences considerably improved the diagnostic ability of MRI. Our results support the inclusion of DWI in the initial MRI protocol for the detection of cervical cancer recurrence, leaving DCE sequences as an option for uncertain cases.Cervical cancer is the fourth most frequent cancer in women worldwide (1). Early stage disease is treated with surgery or chemoradiotherapy and has a good prognosis. However, around 30% of all patients treated for cervical carcinoma develop progressive or recurrent tumors (2).Recurrent cervical cancer is defined as local tumor regrowth or the development of distant organ/lymph node metastases at least six months after regression of the initial lesion. Approximately two-thirds of recurrences appear within the first two years following initial treatment, with 90% recurring by five years post-treatment (3). Risk factors for recurrence include histopathologic features, depth of tumor invasion, and nodal status (4).Pelvic recurrence can be located centrally (cervix, uterus, vagina, parametria, ovaries, bladder, or rectum) or in the pelvic sidewalls. Extrapelvic recurrence most commonly involves the para-aortic lymph nodes, lungs, liver, or bone (4–6).Treatment of recurrent cancer depends on the primary treatment approach, location, and extension. Patients with locally recurrent disease can be offered salvage treatments with curative potential (chemoradiotherapy, if not given previously, or pelvic exenteration in patients who already received chemoradiotherapy). Distant metastases, however, are nearly always incurable (3).In patients who successfully completed primary treatment, surveillance has been advocated to detect the residual or recurrent disease at curable stages (7). The use of imaging studies such as magnetic resonance imaging (MRI) is indicated on the basis of clinical suspicion (8).T2-weighted (T2W) imaging is the reference sequence for cervical cancer staging (9). Recurrent tumors are known to show high signal intensity on T2W MRI, contrasting with the low signal intensity of the cervical stroma. However, some benign conditions such as necrosis, inflammation, and edema may also increase signal intensity on T2W images, representing a potential challenge to the radiologist, particularly after radiotherapy (10–13).Moreover, post-treatment changes can result in areas of fibrosis that are also difficult to differentiate from recurrence (14). MRI has proven to be superior to computed tomography (CT) in distinguishing fibrosis and scarring from active disease, but imaging findings are sometimes indeterminate, complicating the evaluation of recurrent disease (3).In recent years, the functional MRI techniques such as dynamic multiphase contrast-enhanced (DCE) MRI and diffusion-weighted imaging (DWI) have emerged as fundamental tools in female pelvic imaging evaluation (15). Although DCE was shown to be more accurate than T2W alone for tumor recurrence identification, the use of both sequences is recommended (10).Recently, DWI has been added to pelvic MRI protocols to increase diagnostic accuracy in tumor staging. This technique is a functional tool that relies on tissue water displacement to create a contrasted image. For correct evaluation and avoidance of pitfalls, the generated images must be interpreted alongside anatomical sequences. The apparent diffusion coefficient (ADC) map is also needed to reduce image misinterpretation, for example due to the T2 shine-through effect (15). In highly cellular tissues, water movement is restricted and such lesions appear bright at high b-values (1000 s/mm²) and have low ADC value, appearing dark gray on ADC maps in contrast to areas of freely moving water such as urine in the bladder (14). Some recent studies have suggested that DWI and ADC maps can be potentially useful in oncologic follow-up (14, 16).The purpose of this study was to compare the accuracy of T2W/DWI with that of conventional anatomical sequences alone and T2W/DCE imaging sequences in the evaluation of recurrent disease in patients treated for uterine cervical carcinoma.     

Prostate cancer: contouring target and organs at risk by kilovoltage and megavoltage CT and MRI in patients with and without hip prostheses

Objective:

In radiotherapy treatment, planning target volume and organs at risk are contoured on kilovoltage CT (kVCT) images. Unlike MR images, kVCT does not provide precise information on target volume extension. Since neither kVCT nor MRI may be suitable for contouring in patients with ferrous hip prostheses, this study evaluated whether megavoltage CT (MVCT) reduced interobserver variability.

Methods:

Two patients without hip prostheses and one patient (Patient 3) with hip prostheses were enrolled. Six radiation oncologists contoured prostate, rectum and bladder on kVCT (Patients 1 and 3), MRI (Patient 2) and MVCT images (Patient 3). MVCT was acquired with fine, normal and coarse modalities. Interobserver variability for each organ was analysed using conformity index (CI) and coefficient of variation (CV).

Results:

In patients without hip prostheses, CIs were higher in prostate contouring with MRI than with kVCT, indicating lower interobserver variability with MRI. Very slight variations were seen in rectum and bladder contouring. In the patient with hip prostheses (Patient 3), contouring on kVCT lowered CI and increased CV in the prostate, bladder and rectum. The differences were more marked in the prostate. Only fine modality MVCT reduced interobserver variability and only for the prostate.

Conclusion:

Even though greater noise and less soft-tissue contrast increase contouring variability with MVCT than with kVCT, lack of artefacts on MVCT could provide better image definition by this modality in hip prosthesis patients in whom MRI is precluded.

Advances in knowledge:

We recommend the fine modality MVCT for contouring hip prostheses patients.     

Role of magnetic resonance spectroscopic imaging ([1H]MRSI) and dynamic contrast-enhanced MRI (DCE-MRI) in identifying prostate cancer foci in patients with negative biopsy and high levels of prostate-specific antigen (PSA)

Purpose

The purpose of this study was to evaluate the role of magnetic resonance spectroscopic imaging (MRSI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in detecting tumour foci in patients with elevated prostate-specific antigen (PSA) and negative transrectal ultrasonography (TRUS)-guided biopsy.

Materials and methods

This prospective randomised trial was conducted on 150 patients who underwent [¹H]MRSI and DCE-MRI and targeted biopsies of suspicious areas on MRI associated with random biopsies.

Results

After the second biopsy, the diagnosis of prostate adenocarcinoma was made in 64/150 cases. On a perpatient basis, MRSI had 82.8% sensitivity, 91.8% specificity, 88.3% positive predictive value (PPV), 87.8% negative predictive value (NPV) and 85.7% diagnostic accuracy. The sensitivity, specificity, PPV, NPV and accuracy for DCE-MRI was 76.5%, 89.5%, 84.5%, 83.7% and 82%, respectively. The combination of MRSI and DCE-MRI yielded 93.7% sensitivity, 90.7% specificity, 88.2% PPV, 95.1% NPV and 90.9% accuracy in detecting prostate carcinoma.

Conclusions

The combined study with [1H]MRSI and DCE-MRI showed promising results in guiding the biopsy of cancer foci in patients with an initial negative TRUS-guided biopsy.     

Contrast enhanced MRI and Diffusion Weighted Imaging (DWI) in the evaluation of renal cell carcinoma and differentiation of its subtypes

Objective

The prognosis of different histologic subtypes of RCC varies and affects management. Patients with chromophobe or papillary RCC have better prognosis than those with clear cell RCC. The aim of our work was to study the utility of DCE and DWI in the preoperative prediction of renal cell carcinoma subtypes, using histopathology as a gold standard method of diagnosis.

Diffusion-weighted MR imaging and ADC measurement in normal prostate,benign prostatic hyperplasia and prostate carcinoma

Purpose

Our aim was to investigate the diffusion-weighted Imaging (DWI) appearance and apparent diffusion coefficient (ADC) values of normal prostatic gland, prostate carcinoma (PCa) and benign prostate hyperplasia (BPH) and to determine the utility of DWI in their characterization.

Materials and methods

During a period of 16 months, 40 consecutive patients, with elevated PSA level and 12 healthy volunteers with no clinical symptoms or history of prostate disease were prospectively evaluated with DWI of the prostate. MRI was performed using a 1.5T MR scanner equipped with a pelvic phased array coil. For anatomical imaging, T2W FSE in the three orthogonal planes, and T1WI in axial plane were obtained. DWI with b values of 0, 300, 500 and 800 s/mm² were performed in axial plane. The results were confirmed by TRUS-guided biopsy or prostatectomy.

Results

Patients ranged in age from 45 to 85 years (mean 66.6 ± 7.9 year). Twenty patients were confirmed to have BPH, whereas 20 patients had PCa. The mean and SD of ADC values for the peripheral zone (PZ), central gland (CG), BPH nodules and PCa were 1.839 ± 0.233, 1.469 ± 0.239, 1.359 ± 0.201 and 0.87 ± 0.13 respectively. The mean ADC value of PCa was significantly lower than that of CG, PZ, and BPH nodule, with p value <0.05.

Conclusion

DW MR imaging characteristics and ADC values can differentiate PCa and BPH. DWI with ADC may be used as a complementary method to conventional MRI in diagnosis of PCa and BPH.     

Role of novel magnetic resonance imaging sequences in characterization of ovarian masses

Introduction

Differentiating a benign from a malignant adnexal mass would provide a basis for optimal preoperative planning and may also reduce the number of unnecessary laparotomies patients undergoing treatment for benign disease. MRI provides additional information on the composition of soft-tissue masses using differences in MR relaxation properties seen in various types of tissue. More recently developed MRI sequences, like diffusion weighted, susceptibility weighted, and dynamic contrast enhancement sequences provided additional capacities for adnexal lesion tissue characterization.

Aim of the work

The aim of this work was to study the role of MRI including the novel sequences, namely dynamic contrast enhanced MRI (DCE–MRI), diffusion weighted images (DWI) and susceptibility weighted images (SWI) in the characterization of ovarian masses.

Patients and methods

This study included 25 patients having indeterminate adnexal masses at ultrasound. They were subjected to pelvic MRI, including T1, T2, T1 fat sat sequences, as well as the DWI, SWI, and DCE sequences. Final diagnosis was reached through histopathological data, or therapeutic response.

Results

All endometriomas showed blooming on SWI. All malignant lesions showed restricted diffusion and type III DCE curves.

Conclusion

MRI, especially the more recent sequences (DWI, SWI and DCE) allows accurate characterization of ovarian lesions.     

Washout gradient in dynamic contrast-enhanced MRI is associated with tumor aggressiveness of prostate cancer

Purpose:

To investigate the associations between dynamic contrast‐enhanced magnetic resonance imaging (DCE MRI) parameters and the Gleason score (GS) for prostate cancer (PCA) with localization information provided by concurrent apparent diffusion coefficient (ADC) maps.

Materials and Methods:

Forty‐three male patients received MR scans, including diffusion tensor imaging (DTI) and DCE MRI, on a 1.5 T MR system. All patients were confirmed to have PCA in the following biopsy within 2 weeks. ADC maps calculated from DTI were used to colocalize cancerous and noncancerous regions on DCE MRI for perfusion analysis retrospectively. Semiquantitative parameters (peak enhancement, initial gradient, and washout gradient [WG] and quantitative parameters [K^trans, ν_e, and k_ep]) were calculated and correlated with the GS. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of the perfusion parameters in assessing the aggressiveness of PCA.

Results:

A total of 41 PCA nodules were included in the analysis. Among all quantitative and semiquantitative parameters, only WG showed significant correlation with GS (r = ?0.75, P < 0.0001). By defining tumor aggressiveness as a GS >6, WG demonstrated a good diagnostic performance, with the area under the ROC curve being 0.88. Under a cutoff point of WG = 0.125 min^?1, the sensitivity and specificity were 0.87 and 0.78, respectively.

Conclusion:

WG shows a significant association with GS and good diagnostic performance in assessing tumor aggressiveness. Therefore, WG is a potential marker of GS. J. Magn. Reson. Imaging 2012;36:912–919. © 2012 Wiley Periodicals, Inc.