Prostate cancer localization using multiparametric MR imaging: comparison of Prostate Imaging Reporting and Data System (PI-RADS) and Likert scales

Computer-extracted Features Can Distinguish Noncancerous Confounding Disease from Prostatic Adenocarcinoma at Multiparametric MR Imaging

PURPOSE

To determine the best features to discriminate prostate cancer from benign disease and its relationship to benign disease class and cancer grade.

MATERIALS AND METHODS

The institutional review board approved this study and waived the need for informed consent. A retrospective cohort of 70 patients (age range, 48-70 years; median, 62 years), all of whom were scheduled to undergo radical prostatectomy and underwent preoperative 3-T multiparametric magnetic resonance (MR) imaging, including T2-weighted, diffusion-weighted, and dynamic contrast material-enhanced imaging, were included. The digitized prostatectomy slides were annotated for cancer and noncancerous disease and coregistered to MR imaging with an interactive deformable coregistration scheme. Computer-identified features for each of the noncancerous disease categories (eg, benign prostatic hyperplasia [BPH], prostatic intraepithelial neoplasia [PIN], inflammation, and atrophy) and prostate cancer were extracted. Feature selection was performed to identify the features with the highest discriminatory power. The performance of these five features was evaluated by using the area under the receiver operating characteristic curve (AUC).

RESULTS

High-b-value diffusion-weighted images were more discriminative in distinguishing BPH from prostate cancer than apparent diffusion coefficient, which was most suitable for distinguishing PIN from prostate cancer. The focal appearance of lesions on dynamic contrast-enhanced images may help discriminate atrophy and inflammation from cancer. Which imaging features are discriminative for different benign lesions is influenced by cancer grade. The apparent diffusion coefficient appeared to be the most discriminative feature in identifying high-grade cancer. Classification results showed increased performance by taking into account specific benign types (AUC = 0.70) compared with grouping all noncancerous findings together (AUC = 0.62).

CONCLUSION

The best features with which to discriminate prostate cancer from noncancerous benign disease depend on the type of benign disease and cancer grade. Use of the best features may result in better diagnostic performance.

T2-weighted imaging of the prostate: Impact of the BLADE technique on image quality and tumor assessment

PURPOSE

To retrospectively compare standard and BLADE T2-weighted imaging (T2WI) sequences of the prostate in terms of image quality and tumor assessment.

METHODS

49 prostate cancer patients (64 ± 6 years) who underwent 3 T phased-array coil MRI before prostatectomy were included. T2WI was acquired using standard rectilinear and BLADE techniques. Two readers (R1, R2) independently localized the dominant lesion using T2WI alone and using multi-parametric imaging; recorded presence of extraprostatic extension (EPE) in each lobe; and scored lesion conspicuity and absence of motion artifact (1-5 scale; 5 = highest quality). A third reader, unblinded to pathology, placed ROIs to record tumor-to-peripheral-zone contrast. Standard and BLADE T2WI were compared using paired Wilcoxon tests.

RESULTS

BLADE showed a trend toward improved motion artifact for R1 (3.4 ± 1.3 vs. 2.9 ± 1.5; p = 0.054) but not R2 (4.0 ± 1.0 vs. 3.9 ± 1.1; p = 0.880). Dominant lesions showed significantly lower conspicuity using BLADE for R1 (2.8 ± 2.0 vs. 3.2 ± 2.0; p = 0.011) but not R2 (2.3 ± 1.6 vs. 2.4 ± 1.7; p = 0.353), and significantly lower tumor-to-peripheral-zone contrast using BLADE (0.35 ± 0.13 vs. 0.42 ± 0.15; p ≤ 0.001). R1 and R2 correctly localized four and three fewer dominant tumors, respectively, using BLADE than standard T2WI, although both correctly localized a similar fraction of dominant tumors using multi-parametric sequences. While R1 detected EPE in 10 of 11 patients using both sequences, R2 detected EPE in 3 more patients using BLADE.

CONCLUSION

BLADE may help reduce motion artifact of prostate T2WI and assist EPE detection, although at expense of reduced image contrast. In practice, BLADE may be useful in patients in whom initial T2WI is degraded by motion.

Prediction of biochemical recurrence after radical prostatectomy with PI-RADS version 2 in prostate cancers: initial results

OBJECTIVES

To determine whether the Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) helps predict biochemical recurrence (BCR) after radical prostatectomy for prostate cancer (PCa).

METHODS

We included 158 patients with PCa who underwent magnetic resonance imaging (MRI) and radical prostatectomy (RP). Clinical (prostate-specific antigen, greatest percentage of core, and percentage of positive core number), PI-RADSv2 score on MRI, and surgical parameters (Gleason score, extracapsular extension, seminal vesicle invasion, and tumour volume) were investigated. Univariate and multivariate analyses using Cox's proportional hazards model were performed to assess parameters predictive of BCR (two consecutive prostate specific antigens ≥0.2 ng/ml). Kaplan-Meier survival curves were analyzed.

RESULTS

The rate of BCR was 13.3 % (21/158) after surgery (median follow-up, 25 months; range, 12-36). No subject with a PI-RADS score <4 had BCR. In univariate analysis, all parameters were significant for BCR (p < 0.05), except seminal vesicle invasion (p = 0.254). Meanwhile, PI-RADS score was the only independent parameter for BCR in multivariate analysis (p < 0.05). Two-year, BCR-free survival post-RP was significantly lower for PI-RADS ≥4 (84.7-85.5 %) than for PI-RADS <4 (100 %; p < 0.05).

CONCLUSION

As a preoperative imaging tool, PI-RADSv2 may be useful to predict BCR after radical prostatectomy for PCa.

KEY POINTS

• No subject with PI-RADS <4 had BCR after RP • PI-RADSv2 was the only predictor of BCR in multivariate analysis • Two-year, BCR-free survival following RP was lower for PI-RADS≥4 than for PI-RADS<4 • Inter-rater agreement was good for PI-RADS ≥4 or not.

Presence of Magnetic Resonance Imaging Suspicious Lesion Predicts Gleason 7 or Greater Prostate Cancer in Biopsy-Naive Patients

OBJECTIVE

To compare the relative value of magnetic resonance imaging (MRI) in biopsy-naive patients to those with previous negative biopsy. Although MRI-targeted biopsy has been studied in several major prostate cancer (PCa) cohorts (biopsy naive, previous negative biopsy, and active surveillance), the relative benefit in these cohorts has not been established.

METHODS

We retrospectively reviewed biopsy-naive (n = 45) and previous negative biopsy (n = 55) patients who underwent prostate MRI prior to biopsy at our institution. Patients with an MRI suspicious region (MSR) underwent MRI-targeted biopsy as well as a systematic template biopsy, whereas those without MSR underwent only the template biopsy. All biopsies were performed with the TargetScan (Envisioneering, Pittsburgh, PA) biopsy system. MRI targeting was performed with cognitive guidance.

RESULTS

On multivariate logistic regression, the presence of an MSR was the only statistically significant and independent predictor of Gleason ≥ 7 PCa on biopsy for biopsy-naive men (odds ratio [OR] 40.2, P = .01). For men with previous negative biopsy, the presence of MSR was not a predictor of Gleason ≥ 7 PCa on biopsy (OR 4.35, P = .16), whereas PSA density > 0.15 ng/mL(2) was a significant and independent predictor (OR 66.2, P < .01).

CONCLUSION

Prostate MRI should be considered prior to biopsy in all patients presenting with clinical suspicion for PCa, as presence of a MSR will help guide prebiopsy counseling and provide an opportunity for MRI targeting during biopsy.

PI-RADS Prostate Imaging - Reporting and Data System: 2015, Version 2

The Prostate Imaging - Reporting and Data System Version 2 (PI-RADS™ v2) is the product of an international collaboration of the American College of Radiology (ACR), European Society of Uroradiology (ESUR), and AdMetech Foundation. It is designed to promote global standardization and diminish variation in the acquisition, interpretation, and reporting of prostate multiparametric magnetic resonance imaging (mpMRI) examination, and it is based on the best available evidence and expert consensus opinion. It establishes minimum acceptable technical parameters for prostate mpMRI, simplifies and standardizes terminology and content of reports, and provides assessment categories that summarize levels of suspicion or risk of clinically significant prostate cancer that can be used to assist selection of patients for biopsies and management. It is intended to be used in routine clinical practice and also to facilitate data collection and outcome monitoring for research.

Added Value of Multiparametric Ultrasonography in Magnetic Resonance Imaging and Ultrasonography Fusion-guided Biopsy of the Prostate in Patients With Suspicion for Prostate Cancer

OBJECTIVE

To analyze whether magnetic resonance imaging-ultrasonography (MRI-US) fusion-guided biopsy detects more and clinical significant prostate cancer (PCa) in comparison to conventional transrectal US-guided prostate biopsy (PBX) and to investigate if multiparametric (mp) US during MRI-US fusion can further characterize mpMRI-suspected lesions according to the prostate MRI reporting and data system (PI-RADS).

METHODS

From January 2012 to January 2014, 169 patients with a median of 2 negative conventional PBX and/or initially or consistently elevated prostate-specific antigen levels were prospectively included and underwent 3 T mpMRI. Real-time MRI-US fusion scan was used to biopsy the mpMRI-targeted lesions (n = 316). Scanning by mpUS, including B-mode, power Doppler, strain elastography, and contrast-enhanced US was performed to further characterize those lesions and to score by US modalities resulting in an mpUS score. Afterward, a conventional 10-core PBX was performed. PCa detection based on the results of targeted and conventional PBX was estimated. Performances of single US modalities were analyzed. The mpUS score was also investigated for PCa and PI-RADS score prediction.

RESULTS

Among 169 patients, 71 PCa (42%) were detected. From these 71 cases, clinically significant PCa (Gleason score ≥7) were detected exclusively by MRI-US fusion in 31 from 46 cases (67.4%). The highest sensitivity was observed in contrast-enhanced US (85%) and elastography (80%). The mpUS score predicts PCa and PI-RADS score with an overall accuracy of 86% and 80%, respectively.

CONCLUSION

MRI-US fusion-guided PBX detects more clinically significant PCa compared with conventional TRUS. The mpUS score correlates with PI-RADS in PCa prediction.

Updated prostate imaging reporting and data system (PIRADS v2) recommendations for the detection of clinically significant prostate cancer using multiparametric MRI: critical evaluation using whole-mount pathology as standard of reference

OBJECTIVES

To evaluate the recommendations for multiparametric prostate MRI (mp-MRI) interpretation introduced in the recently updated Prostate Imaging Reporting and Data System version 2 (PI-RADSv2), and investigate the impact of pathologic tumour volume on prostate cancer (PCa) detectability on mpMRI.

METHODS

This was an institutional review board (IRB)-approved, retrospective study of 150 PCa patients who underwent mp-MRI before prostatectomy; 169 tumours ≥0.5-mL (any Gleason Score [GS]) and 37 tumours <0.5-mL (GS ≥4+3) identified on whole-mount pathology maps were located on mp-MRI consisting of T2-weighted imaging (T2WI), diffusion-weighted (DW)-MRI, and dynamic contrast-enhanced (DCE)-MRI. Corresponding PI-RADSv2 scores were assigned on each sequence and combined as recommended by PI-RADSv2. We calculated the proportion of PCa foci on whole-mount pathology correctly identified with PI-RADSv2 (dichotomized scores 1-3 vs. 4-5), stratified by pathologic tumour volume.

RESULTS

PI-RADSv2 allowed correct identification of 118/125 (94 %; 95 %CI: 90-99 %) peripheral zone (PZ) and 42/44 (95 %; 95 %CI: 89-100 %) transition zone (TZ) tumours ≥0.5 mL, but only 7/27 (26 %; 95 %CI: 10-42 %) PZ and 2/10 (20 %; 95 %CI: 0-52 %) TZ tumours with a GS ≥4+3, but <0.5 mL. DCE-MRI aided detection of 4/125 PZ tumours ≥0.5 mL and 0/27 PZ tumours <0.5 mL.

CONCLUSIONS

PI-RADSv2 correctly identified 94-95 % of PCa foci ≥0.5 mL, but was limited for the assessment of GS ≥4+3 tumours ≤0.5 mL. DCE-MRI offered limited added value to T2WI+DW-MRI.

KEY POINTS

• PI-RADSv2 correctly identified 95 % of PCa foci ≥0.5 mL • PI-RADSv2 was limited for the assessment of GS ≥4+3 tumours ≤0.5 mL • DCE-MRI offered limited added value to T2WI+DW-MRI.

A prospective comparative analysis of the accuracy of HistoScanning and multiparametric magnetic resonance imaging in the localization of prostate cancer among men undergoing radical prostatectomy

INTRODUCTION

There is increasing interest in using imaging in the detection and localization of prostate cancer (PCa). Both multiparametric magnetic resonance imaging (mpMRI) and HistoScanning (HS) have been independently evaluated in the detection and localization of PCa. We undertook a prospective, blinded comparison of mpMRI and HS for cancer localization among men undergoing radical prostatectomy.

METHODS

Following approval by the institutional review board, men scheduled to undergo radical prostatectomy, who had previously undergone mpMRI at our institution, were offered inclusion in the study. Those consenting underwent preoperative HS following induction of anesthesia; mpMRI, HS, and surgical step-section pathology were independently read by a single radiologist, urologist, and pathologist, respectively, in a blinded fashion. Disease maps created by each independent reader were compared and evaluated for concordance by a 5 persons committee consisting of 2 urologists, 2 pathologists, and 1 radiologist. Logistic regression for correlated data was used to assess and compare mpMRI and HS in terms of diagnostic accuracy for cancer detection. Generalized estimating equations based on binary logistic regression were used to model concordance between reader opinion and the reference standard assessment of the same lesion site or region as a function of imaging modality.

RESULTS

Data from 31/35 men enrolled in the trial were deemed to be evaluable. On evaluation of cancer localization, HS identified cancer in 36/78 (46.2%) regions of interest, as compared with 41/78 (52.6%) on mpMRI (P = 0.3968). The overall accuracy, positive predictive value, negative predictive value, and specificity for detection of disease within a region of interest were significantly better with mpMRI as compared with HS. HS detected 36/84 (42.9%) cancer foci as compared with 42/84 (50%) detected by mpMRI (P = 0.3678). Among tumors with Gleason score>6, mpMRI detected 19/22 (86.4%) whereas HS detected only 11/22 (50%, P = 0.0078). Similarly, among tumors>10mm in maximal diameter, mpMRI detected 28/34 (82.4%) whereas HS detected only 19/34 (55.9%, P = 0.0352).

CONCLUSION

In our institution, the diagnostic accuracy of HS was inferior to that of mpMRI in PCa for PCa detection and localization. Although our study warrants validation from larger cohorts, it would suggest that the HS protocol requires further refinement before clinical implementation.

Five-point Likert scaling on MRI predicts clinically significant prostate carcinoma

Background

To clarify the relationship between the probability of prostate cancer scaled using a 5-point Likert system and the biological characteristics of corresponding tumor foci.

Methods

The present study involved 44 patients undergoing 3.0-Tesla multiparametric MRI before laparoscopic radical prostatectomy. Tracing based on pathological and MRI findings was performed. The relationship between the probability of cancer scaled using the 5-point Likert system and the biological characteristics of corresponding tumor foci was evaluated.

Results

A total of 102 tumor foci were identified histologically from the 44 specimens. Of the 102 tumors, 55 were assigned a score based on MRI findings (score 1: n = 3; score 2: n = 3; score 3: n = 16; score 4: n = 11 score 5: n = 22), while 47 were not pointed out on MRI. The tracing study revealed that the proportion of >0.5 cm³ tumors increased according to the upgrade of Likert scores (score 1 or 2: 33 %; score 3: 68.8 %; score 4 or 5: 90.9 %, χ² test, p < 0.0001). The proportion with a Gleason score >7 also increased from scale 2 to scale 5 (scale 2: 0 %; scale 3: 56.3 %; scale 4: 72.7 %; 5: 90.9 %, χ² test, p = 0.0001). On using score 3 or higher as the threshold of cancer detection on MRI, the detection rate markedly improved if the tumor volume exceeded 0.5 cm³ (<0.2 cm³: 10.3 %; 0.2-0.5 cm³: 25 %; 0.5-1.0 cm³: 66.7 %; 1.0 < cm³: 92.1 %).

Conclusions

Each Likert scale favobably reflected the corresponding tumor’s volume and Gleason score. Our observations show that “score 3 or higher” could be a useful threshold to predict clinically significant carcinoma when considering treatment options.

Prebiopsy MRI and MRI-ultrasound Fusion-targeted Prostate Biopsy in Men With Previous Negative Biopsies: Impact on Repeat Biopsy Strategies

OBJECTIVE

To report outcomes of magnetic resonance imaging (MRI)-ultrasound fusion-targeted biopsy (MRF-TB) and 12-core systematic biopsy (SB) over a 26-month period in men with prior negative prostate biopsy.

MATERIALS AND METHODS

Between June 2012 and August 2014, 210 men presenting to our institution for prostate biopsy with ≥1 prior negative biopsy underwent multiparametric MRI followed by MRF-TB and SB and were entered into a prospective database. Clinical characteristics, maximum mpMRI suspicion scores (mSS), and biopsy results were queried from the database, and the detection rates of Gleason ≥7 prostate cancer (PCa) and overall PCa were compared between biopsy techniques using McNemar's test.

RESULTS

Forty seven (29%) of 161 men meeting inclusion criteria (mean age, 65 ± 8 years; mean prostate-specific antigen, 8.9 ± 8.9) were found to have PCa. MRF-TB and SB had overall cancer detection rates (CDRs) of 21.7% and 18.6% (P = .36), respectively, and CDR for Gleason score (GS) ≥7 disease of 14.9% and 9.3% (P = .02), respectively. Of 26 men with GS ≥7 disease, MRF-TB detected 24 (92.3%) whereas SB detected 15 (57.7%; P < .01). Using UCSF-CAPRA criteria, only 1 man was restratified from low risk to higher risk based on SB results compared to MRF-TB alone. Among men with mSS <4, 72% of detected cancers were low risk by UCSF-CAPRA criteria.

CONCLUSION

In men with previous negative biopsies and persistent suspicion of PCa, SB contributes little to the detection of GS ≥7 disease by MRF-TB, and avoidance of SB bears consideration. Based on the low likelihood of detecting GS ≥7 cancer and overall low-risk features of PCa in men with mSS <4, limiting biopsy to men with mSS ≥4 warrants further investigation.

Image Guided Focal Therapy for Magnetic Resonance Imaging Visible Prostate Cancer: Defining a 3-Dimensional Treatment Margin Based on Magnetic Resonance Imaging Histology Co-Registration Analysis

PURPOSE

We compared prostate tumor boundaries on magnetic resonance imaging and radical prostatectomy histological assessment using detailed software assisted co-registration to define an optimal treatment margin for achieving complete tumor destruction during image guided focal ablation.

MATERIALS AND METHODS

Included in study were 33 patients who underwent 3 Tesla magnetic resonance imaging before radical prostatectomy. A radiologist traced lesion borders on magnetic resonance imaging and assigned a suspicion score of 2 to 5. Three-dimensional reconstructions were created from high resolution digitalized slides of radical prostatectomy specimens and co-registered to imaging using advanced software. Tumors were compared between histology and imaging by the Hausdorff distance and stratified by the magnetic resonance imaging suspicion score, Gleason score and lesion diameter. Cylindrical volume estimates of treatment effects were used to define the optimal treatment margin.

RESULTS

Three-dimensional software based registration with magnetic resonance imaging was done in 46 histologically confirmed cancers. Imaging underestimated tumor size with a maximal discrepancy between imaging and histological boundaries for a given tumor of an average ± SD of 1.99 ± 3.1 mm, representing 18.5% of the diameter on imaging. Boundary underestimation was larger for lesions with an imaging suspicion score 4 or greater (mean 3.49 ± 2.1 mm, p <0.001) and a Gleason score of 7 or greater (mean 2.48 ± 2.8 mm, p = 0.035). A simulated cylindrical treatment volume based on the imaging boundary missed an average 14.8% of tumor volume compared to that based on the histological boundary. A simulated treatment volume based on a 9 mm treatment margin achieved complete histological tumor destruction in 100% of patients.

CONCLUSIONS

Magnetic resonance imaging underestimates histologically determined tumor boundaries, especially for lesions with a high imaging suspicion score and a high Gleason score. A 9 mm treatment margin around a lesion visible on magnetic resonance imaging would consistently ensure treatment of the entire histological tumor volume during focal ablative therapy.

Likert score 3 prostate lesions: Association between whole-lesion ADC metrics and pathologic findings at MRI/ultrasound fusion targeted biopsy

BACKGROUND

To assess associations between whole-lesion apparent diffusion coefficient (ADC) metrics and pathologic findings of Likert score 3 prostate lesions at MRI/ultrasound fusion targeted biopsy.

METHODS

This retrospective Institutional Review Board-approved study received a waiver of consent. We identified patients receiving a highest lesion score of 3 on 3 Tesla multiparametric MRI reviewed by a single experienced radiologist using a 5-point Likert scale and who underwent fusion biopsy. A total of 188 score 3 lesions in 158 patients were included. Three-dimensional volumes-of-interest encompassing each lesion were traced on ADC maps. Logistic regression was used to predict biopsy results based on whole-lesion ADC metrics and patient biopsy history. Biopsy yield was compared between metrics.

RESULTS

By lesion, targeted biopsy identified tumor in 22.3% and Gleason score (GS) > 6 tumor in 8.5%, although results varied by biopsy history: biopsy-naïve (n = 80), 20.0%/8.8%; prior negative biopsy (n = 53), 9.4%/1.9%; prior positive biopsy (n = 55): 40.0%/14.5%. Biopsy history, whole-lesion mean ADC, whole-lesion ADC10-25 , and whole-lesion ADC25-50 were each significantly associated with tumor or GS > 6 tumor at fusion biopsy (P ≤ 0.047). In men without prior negative prostate biopsy, whole-lesion ADC25-50  ≤ 1.04*10(-3) mm2 /s achieved 90.0% sensitivity and 50.0% specificity for GS > 6 tumor, which was significantly higher (P < 0.001) than specificity of PSA (17.5%) at identical sensitivity.

CONCLUSION

For score 3 lesions in patients without prior negative biopsy, whole-lesion ADC metrics help detect GS > 6 cancer while avoiding negative biopsies. However, deferral of fusion biopsy may be considered for score 3 lesions in patients with prior negative biopsy (without applying whole-lesion ADC metrics) given exceedingly low (∼ 2%) frequency of GS > 6 tumor in this group.

Classifying CT/MR findings in patients with suspicion of hepatocellular carcinoma: Comparison of liver imaging reporting and data system and criteria-free Likert scale reporting models

PURPOSE

To compare the Liver Imaging Reporting and Data System (LI-RADS) and a criteria-free Likert scale (LS) reporting models for classifying computed tomography/magnetic resonance imaging (CT/MR) findings of suspicious hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Imaging data of 281 hepatic nodules in 203 patients were retrospectively included. Imaging characteristics including diameter, arterial hyperenhancement, washout, and capsule were reviewed independently by two groups of readers using LI-RADS and LS (range, score 1-5). LS is primarily based on the overall impression of image findings without using fixed criteria. Interreader agreement (IRA), intraclass agreement (ICA), and diagnostic performance were determined by Fleiss, Cohen's kappa (κ), and logistic regression, respectively.

RESULTS

There were 167 contrast-enhanced CT (CECT) versus 114 MR data. Overall, IRA was moderate (κ = 0.47, 0.52); IRA was moderate-to-good for arterial hyperenhancement, washout, and capsule (κ = 0.56-0.69); excellent for diameter and tumor embolus (κ = 0.99). Overall, ICA between LI-RADS and LS was moderate (κ = 0.44-0.50); ICA was good for scores 1-2 (κ = 0.71-0.90), moderate for scores 3 and 5 (κ = 0.41-0.52), but very poor for score 4 (κ = 0.11-0.19). LI-RADS produced significantly lower accuracy (78.6% vs. 87.2%) and sensitivity (72.1% vs. 92.8%), higher specificity (97.3% vs. 71.2%) and positive likelihood ratio (+LR: 26.32 vs. 3.23) in diagnosis of HCC. CECT produced relatively low IRA, ICA, and diagnostic ability against MR.

CONCLUSION

There were substantial variations in liver observations between LI-RADS and LS. Further study is needed to investigate ICA between CECT and MR.

Relationship Between Prebiopsy Multiparametric Magnetic Resonance Imaging (MRI), Biopsy Indication, and MRI-ultrasound Fusion-targeted Prostate Biopsy Outcomes

BACKGROUND

Increasing evidence supports the use of magnetic resonance imaging (MRI)-ultrasound fusion-targeted prostate biopsy (MRF-TB) to improve the detection of clinically significant prostate cancer (PCa) while limiting detection of indolent disease compared to systematic 12-core biopsy (SB).

OBJECTIVE

To compare MRF-TB and SB results and investigate the relationship between biopsy outcomes and prebiopsy MRI.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective analysis of a prospectively acquired cohort of men presenting for prostate biopsy over a 26-mo period. A total of 601 of 803 consecutively eligible men were included.

INTERVENTIONS

All men were offered prebiopsy MRI and assigned a maximum MRI suspicion score (mSS). Men with an MRI abnormality underwent combined MRF-TB and SB.

OUTCOMES

Detection rates for all PCa and high-grade PCa (Gleason score [GS] ≥7) were compared using the McNemar test.

RESULTS AND LIMITATIONS

MRF-TB detected fewer GS 6 PCas (75 vs 121; p<0.001) and more GS ≥7 PCas (158 vs 117; p<0.001) than SB. Higher mSS was associated with higher detection of GS ≥7 PCa (p<0.001) but was not correlated with detection of GS 6 PCa. Prediction of GS ≥7 disease by mSS varied according to biopsy history. Compared to SB, MRF-TB identified more GS ≥7 PCas in men with no prior biopsy (88 vs 72; p=0.012), in men with a prior negative biopsy (28 vs 16; p=0.010), and in men with a prior cancer diagnosis (42 vs 29; p=0.043). MRF-TB detected fewer GS 6 PCas in men with no prior biopsy (32 vs 60; p<0.001) and men with prior cancer (30 vs 46; p=0.034). Limitations include the retrospective design and the potential for selection bias given a referral population.

CONCLUSIONS

MRF-TB detects more high-grade PCas than SB while limiting detection of GS 6 PCa in men presenting for prostate biopsy. These findings suggest that prebiopsy multiparametric MRI and MRF-TB should be considered for all men undergoing prostate biopsy. In addition, mSS in conjunction with biopsy indications may ultimately help in identifying men at low risk of high-grade cancer for whom prostate biopsy may not be warranted.

PATIENT SUMMARY

We examined how magnetic resonance imaging (MRI)-targeted prostate biopsy compares to traditional systematic biopsy in detecting prostate cancer among men with suspicion of prostate cancer. We found that MRI-targeted biopsy detected more high-grade cancers than systematic biopsy, and that MRI performed before biopsy can predict the risk of high-grade cancer.

Evaluation of the European Society of Urogenital Radiology (ESUR) PI-RADS scoring system for assessment of extra-prostatic extension in prostatic carcinoma

INTRODUCTION

To evaluate extra-prostatic extension (EPE) comparing PI-RADS to non-standardized reporting.

MATERIALS AND METHODS

With IRB approval, 145 consecutive patients underwent radical prostatectomy (RP) and multi-parametric (T2W+DWI+DCE) MRI between 2012 and 2013. Eighty patients (66.3% with EPE) were staged without PI-RADS and 65 patients (64.6% with EPE) were staged using a 5-point PI-RADS scoring system. Studies were reported by fellowship-trained radiologists in routine clinical practice. Individual PIRADS scores were assessed using ROC to determine the score which optimized sensitivity/specificity. Diagnostic accuracy for EPE was compared with/without PI-RADS using the McNemar test. Subgroup analysis by radiologist experience was performed using Spearman correlation and chi-square.

RESULTS

Area under ROC curve for EPE using PI-RADS was 0.62 and optimal sensitivity/specificity was achieved with PI-RADS score ≥ 3. Compared to non-standardized reporting, sensitivity for EPE improved with PI-RADS (59.5% [49.1-68.2] vs. 24.5% [16.7-31.2]), p=0.01; with no difference in specificity (68.0% [50.5-82.6]) vs. (75.0% [60.1-87.6]), p=0.06. Overall accuracy improved with PI-RADS (62.7% [49.6-73.6] vs. 42.0% [31.7-50.7%]), p=0.006. Diagnostic accuracy was better among experienced radiologists without PI-RADS (p=0.005); however, there was no difference in accuracy by reader experience using PI-RADS (p=0.24).

CONCLUSION

The PI-RADS criteria for EPE improves sensitivity without reducing specificity. PI-RADS may reduce differences in accuracy by reader experience.

Magnetic Resonance Imaging-Ultrasound Fusion Targeted Prostate Biopsy in a Consecutive Cohort of Men with No Previous Biopsy: Reduction of Over Detection through Improved Risk Stratification

PURPOSE

MRF-TB (magnetic resonance imaging-ultrasound fusion targeted prostate biopsy) may improve the detection of prostate cancer in men presenting for prostate biopsy. We report clinical outcomes of 12-core systematic biopsy and MRF-TB in men who presented for primary biopsy and further describe pathological characteristics of cancers detected by systematic biopsy and not by MRF-TB.

MATERIALS AND METHODS

Clinical outcomes of 452 consecutive men who underwent prebiopsy multiparametric magnetic resonance imaging followed by MRF-TB and systematic biopsy at our institution between June 2012 and June 2015 were captured in an institutional review board approved database. Clinical characteristics, biopsy results and magnetic resonance imaging suspicion scores were queried from the database.

RESULTS

Prostate cancer was detected in 207 of 382 men (54.2%) with a mean±SD age of 64±8.5 years and mean±SEM prostate specific antigen 6.8±0.3 ng/ml who met study inclusion criteria. The cancer detection rate of systematic biopsy and MRF-TB was 49.2% and 43.5%, respectively (p=0.006). MRF-TB detected more Gleason score 7 or greater cancers than systematic biopsy (117 of 132 or 88.6% vs 102 of 132 or 77.3%, p=0.037). Of 41 cancers detected by systematic biopsy but not by MRF-TB 34 (82.9%) demonstrated Gleason 6 disease, and 26 (63.4%) and 34 (82.9%) were clinically insignificant by Epstein criteria and a UCSF CAPRA (University of California-San Francisco-Cancer of the Prostate Risk Assessment) score of 2 or less, respectively.

CONCLUSIONS

In men presenting for primary prostate biopsy MRF-TB detects more high grade cancers than systematic biopsy. Most cancers detected by systematic biopsy and not by MRF-TB are at clinically low risk. Prebiopsy magnetic resonance imaging followed by MRF-TB decreases the detection of low risk cancers while significantly improving the detection and risk stratification of high grade disease.

Prostate Cancer: Interobserver Agreement and Accuracy with the Revised Prostate Imaging Reporting and Data System at Multiparametric MR Imaging

PURPOSE

To evaluate accuracy and interobserver variability with the use of the Prostate Imaging Reporting and Data System (PI-RADS) version 2.0 for detection of prostate cancer at multiparametric magnetic resonance (MR) imaging in a biopsy-naïve patient population.

MATERIALS AND METHODS

This retrospective HIPAA-compliant study was approved by the local ethics committee, and written informed consent was obtained from all patients for use of their imaging and histopathologic data in future research studies. In 101 biopsy-naïve patients with elevated prostate-specific antigen levels who underwent multiparametric MR imaging of the prostate and subsequent transrectal ultrasonography (US)-MR imaging fusion-guided biopsy, suspicious lesions detected at multiparametric MR imaging were scored by five readers who were blinded to pathologic results by using to the newly revised PI-RADS and the scoring system developed in-house. Interobserver agreement was evaluated by using κ statistics, and the correlation of pathologic results with each of the two scoring systems was evaluated by using the Kendall τ correlation coefficient.

RESULTS

Specimens of 162 lesions in 94 patients were sampled by means of transrectal US-MR imaging fusion biopsy. Results for 87 (54%) lesions were positive for prostate cancer. Kendall τ values with the PI-RADS and the in-house-developed scoring system, respectively, at T2-weighted MR imaging in the peripheral zone were 0.51 and 0.17 and in the transitional zone, 0.45 and -0.11; at diffusion-weighted MR imaging, 0.42 and 0.28; at dynamic contrast material-enhanced MR imaging, 0.23 and 0.24, and overall suspicion scores were 0.42 and 0.49. Median κ scores among all possible pairs of readers for PI-RADS and the in-house-developed scoring system, respectively, for T2-weighted MR images in the peripheral zone were 0.47 and 0.15; transitional zone, 0.37 and 0.07; diffusion-weighted MR imaging, 0.41 and 0.57; dynamic contrast-enhanced MR imaging, 0.48 and 0.41; and overall suspicion scores, 0.46 and 0.55.

CONCLUSION

Use of the revised PI-RADS provides moderately reproducible MR imaging scores for detection of clinically relevant disease.

Evaluation of Multiparametric Magnetic Resonance Imaging in Detection and Prediction of Prostate Cancer

Background

Although European Society of Urogenital Radiology proposed the potential of multiparametric magnetic resonance imaging (MP-MRI) as a tool in the diagnostic pathway for prostate cancer (PCa) and published a unified scoring system named Prostate Imaging Reporting and Data System (PI-RADS version 1), these still need to be validated by real-life studies.

Objective

To evaluate the role of MP-MRI in detection and prediction of PCa.

Methods

Patients with clinical suspicion of PCa who underwent prebiopsy MP-MRI from 2002 to 2009 were recruited. MP-MRI results were retrospectively assigned as overall scores using PI-RADS by two radiologists. Patients were followed and the end point was the diagnosis of PCa. Receiver operating characteristics (ROC) curve was performed to test diagnostic efficacy of MP-MRI, under results of biopsy within three months. The cox proportional hazards model was used to identify independent variables for the detection of PCa.

Results

Finally, 1113 of the 1806 enrolled patients were included for analysis. The median follow-up was 56.0 months (1–137 mo). For 582 patients biopsied within three months, area under the curve for the detection of PCa with MP-MRI was 0.88 (95% confidence interval [CI], 0.75–1.00) in group of baseline prostate specific antigen (PSA) 0.01–4.00 ng/ml (n = 31), 0.90 (95% CI, 0.84–0.95) in PSA 4.01–10.00 ng/ml (n = 142), and 0.91 (95% CI, 0.87–0.94) in PSA >10.00 ng/ml (n = 409), respectively. In the cox model adjusted for age and baseline PSA level, for the detection rate of PCa, compared with PI-RADS 1–2 (reference), the hazard ratio was 6.43 (95% CI, 4.29–9.65) for PI-RADS 3, 18.58 (95% CI, 13.36–25.84) for PI-RADS 4–5 (p < 0.001).

Conclusions

Prebiopsy MP-MRI with PI-RADS is demonstrated as a valuable diagnostic and predictive tool for PCa.

Clinical evaluation of a computer-aided diagnosis system for determining cancer aggressiveness in prostate MRI

Objectives

To investigate the added value of computer-aided diagnosis (CAD) on the diagnostic accuracy of PIRADS reporting and the assessment of cancer aggressiveness.

Methods

Multi-parametric MRI and histopathological outcome of MR-guided biopsies of a consecutive set of 130 patients were included. All cases were prospectively PIRADS reported and the reported lesions underwent CAD analysis. Logistic regression combined the CAD prediction and radiologist PIRADS score into a combination score. Receiver-operating characteristic (ROC) analysis and Spearman’s correlation coefficient were used to assess the diagnostic accuracy and correlation to cancer grade. Evaluation was performed for discriminating benign lesions from cancer and for discriminating indolent from aggressive lesions.

Results

In total 141 lesions (107 patients) were included for final analysis. The area-under-the-ROC-curve of the combination score was higher than for the PIRADS score of the radiologist (benign vs. cancer, 0.88 vs. 0.81, p = 0.013 and indolent vs. aggressive, 0.88 vs. 0.78, p < 0.01). The combination score correlated significantly stronger with cancer grade (0.69, p = 0.0014) than the individual CAD system or radiologist (0.54 and 0.58).

Conclusions

Combining CAD prediction and PIRADS into a combination score has the potential to improve diagnostic accuracy. Furthermore, such a combination score has a strong correlation with cancer grade.

Key Points

• Computer-aided diagnosis helps radiologists discriminate benign findings from cancer in prostate MRI.

• Combining PIRADS and computer-aided diagnosis improves differentiation between indolent and aggressive cancer.

• Adding computer-aided diagnosis to PIRADS increases the correlation coefficient with respect to cancer grade.

Natural History of Pathologically Benign Cancer Suspicious Regions on Multiparametric Magnetic Resonance Imaging Following Targeted Biopsy

PURPOSE

We determined the natural history of pathologically benign cancer suspicious regions on multiparametric magnetic resonance imaging following targeted biopsy.

MATERIALS AND METHODS

Between January 2012 and September 2014, 330 men underwent prostate multiparametric magnetic resonance imaging. A total of 533 cancer suspicious regions were identified and scored on a Likert scale of 1 to 5 based on suspicion for malignancy with 5 indicating the highest suspicion level. Following multiparametric magnetic resonance imaging all men underwent magnetic resonance imaging-ultrasound fusion targeted prostate biopsy using ProFuse software and the ei-Nav|Artemis system (innoMedicus, Cham, Switzerland), and a computer generated 12-core random biopsy. We analyzed a cohort of 34 men with a total of 51 cancer suspicious regions who had benign prostate biopsies and underwent repeat multiparametric magnetic resonance imaging and prostate specific antigen testing at 1 year. Changes in the greatest linear measurement, the suspicion score and serum prostate specific antigen were ascertained.

RESULTS

During 1 year the suspicion score distribution and the mean greatest linear measurement of the cancer suspicious regions decreased significantly (p <0.0001) while mean prostate specific antigen did not significantly change (p = 0.632). Two (3.9%), 15 (29.4%) and 34 cancer suspicious regions (66.7%) showed an increase, no change and decrease in suspicion score, respectively. No (0%), 21 (42.0%) and 29 cancer suspicious regions (58.0%) showed an increase of 20% or greater, no change and a decrease of 20% or greater in greatest linear measurement, respectively. Of the 2 cancer suspicious regions exhibiting an increased suspicion score neither showed a prostate specific antigen increase of 0.5 ng/ml or greater.

CONCLUSIONS

Our study provides compelling evidence that few benign cancer suspicious regions increase in suspicion score and/or the greatest linear measurement within 1 year independent of the baseline suspicion score. Therefore, routinely repeating multiparametric magnetic resonance imaging at 1 year in men with pathologically benign cancer suspicious regions should be discouraged since it is unlikely to influence management decisions.

Current role of multiparametric magnetic resonance imaging in the management of prostate cancer

The purpose of this review was to evaluate the current role of multiparametric magnetic resonance imaging (mp-MRI) in the management of prostate cancer (PC). The diagnosis of PC remains controversial owing to overdetection of indolent disease, which leads to overtreatment and subsequent patient harm. mp-MRI has the potential to equilibrate the imbalance between detection and treatment. The limitation of the data for analysis with this new technology is problematic, however. This issue has been compounded by a paradigm shift in clinical practice aimed at utilizing this modality, which has been rolled out in an ad hoc fashion often with commercial motivation. Despite a growing body of literature, pertinent clinical questions remain. For example, can mp-MRI be calibrated to reliably detect biologically significant disease? As with any new technology, objective evaluation of the clinical applications of mp-MRI is essential. The focus of this review was on the evaluation of mp-MRI of the prostate with respect to clinical utility.

ProstateAnalyzer: Web-based medical application for the management of prostate cancer using multiparametric MR imaging

OBJECTIVES

In this paper, we present ProstateAnalyzer, a new web-based medical tool for prostate cancer diagnosis. ProstateAnalyzer allows the visualization and analysis of magnetic resonance images (MRI) in a single framework.

METHODS

ProstateAnalyzer recovers the data from a PACS server and displays all the associated MRI images in the same framework, usually consisting of 3D T2-weighted imaging for anatomy, dynamic contrast-enhanced MRI for perfusion, diffusion-weighted imaging in the form of an apparent diffusion coefficient (ADC) map and MR Spectroscopy. ProstateAnalyzer allows annotating regions of interest in a sequence and propagates them to the others.

RESULTS

From a representative case, the results using the four visualization platforms are fully detailed, showing the interaction among them. The tool has been implemented as a Java-based applet application to facilitate the portability of the tool to the different computer architectures and software and allowing the possibility to work remotely via the web.

CONCLUSION

ProstateAnalyzer enables experts to manage prostate cancer patient data set more efficiently. The tool allows delineating annotations by experts and displays all the required information for use in diagnosis. According to the current European Society of Urogenital Radiology guidelines, it also includes the PI-RADS structured reporting scheme.

Prostate Imaging Reporting and Data System and Likert Scoring System: Multiparametric MR Imaging Validation Study to Screen Patients for Initial Biopsy

PURPOSE

To compare the diagnostic performance of the magnetic resonance (MR) imaging-based Prostate Imaging Reporting and Data System (PI-RADS) and a Likert scale in the detection of prostate cancer in a cohort of patients undergoing initial prostate biopsy.

MATERIALS AND METHODS

This institutional review board-approved two-center prospective study included 118 patients with normal digital rectal examination (DRE) results but elevated prostate-specific antigen (PSA) levels (4-20 ng/mL) who were referred for initial prostate biopsies and had one suspicious (Likert scale score, ≥3) focus at prebiopsy 1.5-T multiparametric MR imaging performed with T2-weighted, diffusion-weighted [DW], and dynamic contrast material-enhanced imaging. Targeted core biopsies and random systematic core biopsies were performed. The elementary unit for analysis was the core. Relationships were assessed by using the Mann-Whitney U test. Yates corrected and Pearson χ(2) tests were used to evaluate categoric variables. A training set was randomly drawn to construct the receiver operating characteristic curves for the summed PI-RADS scores and for the Likert scale scores. The thresholds to recommend biopsy were obtained from the Youden J statistics and were tested in the remaining validation set in terms of predictive characteristics. Interobserver variability was analyzed by using weighed κ statistics in a random set of 50 patients.

RESULTS

Higher T2-weighted, DW, and dynamic contrast-enhanced imaging PI-RADS scores were observed in areas that yielded cancer-positive cores. The percentage of positive cores increased with the sum of scores aggregated in five classes as follows: For summed PI-RADS scores of 3-5, the percentage of positive cores was 2.3%; for scores of 6-8, it was 5.8%; for scores of 9 or 10, it was 24.7%; for scores of 11 or 12, it was 51.8%; and for scores of 13-15, it was 72.1% (P for trend, <.0001). For the threshold of summed PI-RADS scores of 9 or greater, sensitivity was 86.6%, specificity was 82.4%, the positive predictive value was 52.4%, the negative predictive value was 96.5%, and accuracy was 83.2%. The respective data for Likert scale scores of 3 or greater were 93.8%, 73.6%, 44.3%, 98.1%, and 73.3%. Good interobserver agreement was observed for the Likert scale (κ = 0.80) and the summed PI-RADS (κ = 0.73) scoring systems.

CONCLUSION

PI-RADS provided the site-specific stratified risk of cancer-positive cores in biopsy-naive men with normal DRE results and elevated PSA levels. There was no significant difference between summed PI-RADS scores of 9 or greater and Likert scale scores of 3 or greater in the detection of cancer in the peripheral zone.

Evaluation of the prostate imaging reporting and data system for the detection of prostate cancer by the results of targeted biopsy of the prostate

PURPOSE

The purpose of this study was to evaluate the magnetic resonance prostate imaging reporting and data system (PI-RADS) for the detection of prostate cancer by the results of magnetic resonance imaging (MRI)-guided biopsy of the prostate as a reference standard.

PATIENTS AND METHODS

In 55 patients who had undergone MRI-guided biopsy of the prostate, we retrospectively matched every biopsy core with the corresponding lesion in previously acquired endorectal multiparametric MRI including T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced MRI (DCE-MRI) at 1.5 T. Two readers blinded to the results of the biopsy evaluated each biopsied lesion according to the PI-RADS scoring system. The results of the targeted biopsy were used as a reference standard. Receiver operating characteristic analysis was performed for statistical analysis.

RESULTS

A total of 113 lesions in the 55 patients were evaluated; 30 lesions were malignant. When evaluated according to the criteria of the PI-RADS scoring system, DCE-MRI revealed a lower area under the receiver operating characteristic curve (AUC) (0.76) compared with T2WI (0.88; P=0.06) and DWI (0.93; P=0.004). A sum score combining T2WI, DWI, and DCE-MRI yielded an AUC of 0.93, whereas a sum score combining only T2WI and DWI yielded an AUC of 0.95. In central gland lesions, T2WI showed a numerically higher AUC compared with DWI (0.98 and 0.95), whereas, in peripheral zone lesions, DWI was superior (AUC of 0.93 and 0.73; P=0.04). An approach assigning a PI-RADS score for T2WI to central gland lesions and for DWI to peripheral zone lesions yielded an AUC of 0.96 and was numerically superior compared with any sequence alone and sum scores combining T2WI and DWI as well as T2WI, DWI, and DCE-MRI.

CONCLUSIONS

The PI-RADS scoring system shows a good diagnostic performance for the detection of prostate cancer when using a sum score. However, DCE-MRI does not seem to add significant value when evaluated according to the recommended criteria. Assigning a score for T2WI to central gland lesions and for DWI to peripheral zone lesions might be sufficient for stratification of patients for further diagnostic workup.

Characterization of prostate cancer using T2 mapping at 3T: a multi-scanner study

RATIONALE AND OBJECTIVES

To assess the prostate T2 value as a predictor of malignancy on two different 3T scanners.

PATIENTS AND METHODS

Eighty-three pre-prostatectomy multiparametric MRIs were retrospectively evaluated [67 obtained on a General Electric MRI (scanner 1) and 16 on a Philips MRI (scanner 2)]. After correlation with prostatectomy specimens, readers measured the T2 value of regions-of-interest categorized as "cancers", "false positive lesions", or "normal tissue".

RESULTS

On scanner 1, in PZ, cancers had significantly lower T2 values than false positive lesions (P=0.02) and normal tissue (P=2×10(-9)). Gleason≥6 cancers had similar T2 values than false positive lesions and significantly higher T2 values than Gleason≥7 cancers (P=0.009). T2 values corresponding to a 25% and 75% risk of Gleason≥7 malignancy were respectively 132 ms (95% CI: 129-135 ms) and 77 ms (95% CI: 74-81 ms). In TZ, cancers had significantly lower T2 values than normal tissue (P=0.008), but not than false positive findings. Mean T2 values measured on scanner 2 were not significantly different than those measured on scanner 1 for all tissue classes.

CONCLUSION

All tested tissue classes had similar mean T2 values on both scanners. In PZ, the T2 value was a significant predictor of Gleason≥7 cancers.

How accurate is multiparametric MR imaging in evaluation of prostate cancer volume?

PURPOSE

To assess the factors influencing multiparametric (MP) magnetic resonance (MR) imaging accuracy in estimating prostate cancer histologic volume (Vh).

MATERIALS AND METHODS

A prospective database of 202 patients who underwent MP MR imaging before radical prostatectomy was retrospectively used. Institutional review board approval and informed consent were obtained. Two independent radiologists delineated areas suspicious for cancer on images (T2-weighted, diffusion-weighted, dynamic contrast material-enhanced [DCE] pulse sequences) and scored their degree of suspicion of malignancy by using a five-level Likert score. One pathologist delineated cancers on whole-mount prostatectomy sections and calculated their volume by using digitized planimetry. Volumes of MR true-positive lesions were measured on T2-weighted images (VT2), on ADC maps (VADC), and on DCE images [VDCE]). VT2, VADC, VDCE and the greatest volume determined on images from any of the individual MR pulse sequences (Vmax) were compared with Vh (Bland-Altman analysis). Factors influencing MP MR imaging accuracy, or A, calculated as A = Vmax/Vh, were evaluated using generalized linear mixed models.

RESULTS

For both readers, Vh was significantly underestimated with VT2 (P < .0001, both), VADC (P < .0001, both), and VDCE (P = .02 and P = .003, readers 1 and 2, respectively), but not with Vmax (P = .13 and P = .21, readers 1 and 2, respectively). Mean, 25th percentile, and 75th percentile, respectively, for Vmax accuracy were 0.92, 0.54, and 1.85 for reader 1 and 0.95, 0.57, and 1.77 for reader 2. At generalized linear mixed (multivariate) analysis, tumor Likert score (P < .0001), Gleason score (P = .009), and Vh (P < .0001) significantly influenced Vmax accuracy (both readers). This accuracy was good in tumors with a Gleason score of 7 or higher or a Likert score of 5, with a tendency toward underestimation of Vh; accuracy was poor in small (<0.5 cc) or low-grade (Gleason score ≤6) tumors, with a tendency toward overestimation of Vh.

CONCLUSION

Vh can be estimated by using Vmax in aggressive tumors or in tumors with high Likert scores.

Use of the Prostate Imaging Reporting and Data System (PI-RADS) for Prostate Cancer Detection with Multiparametric Magnetic Resonance Imaging: A Diagnostic Meta-analysis

CONTEXT

In 2012, an expert panel of the European Society of Urogenital Radiology (ESUR) published the Prostate Imaging Reporting and Data System (PI-RADS) for prostate cancer (PC) detection with multiparametric magnetic resonance imaging (mp-MRI). Since then, many centers have reported their experiences.

PURPOSE

To review the diagnostic accuracy of PI-RADS for PC detection with mp-MRI.

EVIDENCE ACQUISITION

We searched Medline and Embase up to March 20, 2014. We included diagnostic accuracy studies since 2012 that used PI-RADS with mp-MRI for PC detection in men, using prostatectomy or biopsy as the reference standard. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool by two independent reviewers. Data necessary to complete 2×2 contingency tables were obtained from the included studies, and test characteristics including sensitivity and specificity were calculated. Results were pooled and plotted in a summary receiver operating characteristics plot.

EVIDENCE SYNTHESIS

Fourteen studies (1785 patients) could be analyzed. The pooled data showed sensitivity of 0.78 (95% confidence interval [CI] 0.70-0.84) and specificity of 0.79 (95% CI 0.68-0.86) for PC detection, with negative predictive values ranging from 0.58 to 0.95. Sensitivity analysis revealed pooled sensitivity of 0.82 (95% CI 0.72-0.89) and specificity of 0.82 (95% CI 0.67-0.92) in studies with correct use of PI-RADS (ie, clear description in the methodology and no adjustment of criteria). For studies with a less strict or adjusted use of PI-RADS criteria, or unclear description of the methodology, had pooled sensitivity of 0.73 (95% CI 0.62-0.82) and specificity of 0.75 (95% CI 0.61-0.84).

CONCLUSIONS

In patients for whom PC is suspected, PI-RADS appears to have good diagnostic accuracy in PC detection, but no recommendation regarding the best threshold can be provided because of heterogeneity.

PATIENT SUMMARY

Pooling of results from all previous studies that used a relatively new 5-point scoring system for prostate magnetic resonance imaging showed that this scoring system appears to be able to detect prostate cancer accurately.

Shear wave elastography for localization of prostate cancer lesions and assessment of elasticity thresholds: implications for targeted biopsies and active surveillance protocols

PURPOSE

Shear wave elastography allows the detection of cancer by using focused ultrasound pulses for locally deforming tissue. The differences in tissue elasticity and stiffness have been used increasingly in breast cancer imaging and help detect potential tumor lesions in the prostate. In this study we localized prostate cancer lesions using shear wave elastography before radical prostatectomy and assessed the examiner independent elasticity threshold for cancer foci detection.

MATERIALS AND METHODS

Shear wave elastography scanning of the whole prostate was performed before radical prostatectomy in 60 consecutive patients with high, intermediate and low risk disease. Localization of suspected lesions and density threshold (kPa) were recorded in up to 12 areas and resulted in 703 different fields. Shear wave elastography findings were correlated with final pathology. Initially 381 areas were used to establish shear wave elastography cutoffs (development cohort 32 patients). Subsequently these cutoffs were validated in 322 areas (validation cohort 28 patients).

RESULTS

Using shear wave elastography significant differences were recorded for the elasticity of benign tissue vs prostate cancer nodules at 42 kPa (range 29 to 71.3) vs 88 kPa (range 54 to 132) (all p <0.001). Median cancer lesion diameter was 26 mm (range 18 to 41). Applying the most informative cutoff of 50 kPa to the validation cohort resulted in 80.9% and 69.1% sensitivity and specificity, respectively, and 74.2% accuracy for detecting cancer nodules based on final pathological finding. The corresponding positive and negative predictive values were 67.1% and 82.2%, respectively.

CONCLUSIONS

Shear wave elastography allows the identification of cancer foci based on shear wave elastography differences. Moreover, reliable cutoffs for this approach can be established, allowing examiner independent localization of prostate cancer foci.

Transperineal in-bore 3-T MR imaging-guided prostate biopsy: a prospective clinical observational study

PURPOSE

To determine the detection rate, clinical relevance, Gleason grade, and location of prostate cancer ( PCa prostate cancer ) diagnosed with and the safety of an in-bore transperineal 3-T magnetic resonance (MR) imaging-guided prostate biopsy in a clinically heterogeneous patient population.

MATERIALS AND METHODS

This prospective retrospectively analyzed study was HIPAA compliant and institutional review board approved, and informed consent was obtained. Eighty-seven men (mean age, 66.2 years ± 6.9) underwent multiparametric endorectal prostate MR imaging at 3 T and transperineal MR imaging-guided biopsy. Three subgroups of patients with at least one lesion suspicious for cancer were included: men with no prior PCa prostate cancer diagnosis, men with PCa prostate cancer who were undergoing active surveillance, and men with treated PCa prostate cancer and suspected recurrence. Exclusion criteria were prior prostatectomy and/or contraindication to 3-T MR imaging. The transperineal MR imaging-guided biopsy was performed in a 70-cm wide-bore 3-T device. Overall patient biopsy outcomes, cancer detection rates, Gleason grade, and location for each subgroup were evaluated and statistically compared by using χ(2) and one-way analysis of variance followed by Tukey honestly significant difference post hoc comparisons.

RESULTS

Ninety biopsy procedures were performed with no serious adverse events, with a mean of 3.7 targets sampled per gland. Cancer was detected in 51 (56.7%) men: 48.1% (25 of 52) with no prior PCa prostate cancer , 61.5% (eight of 13) under active surveillance, and 72.0% (18 of 25) in whom recurrence was suspected. Gleason pattern 4 or higher was diagnosed in 78.1% (25 of 32) in the no prior PCa prostate cancer and active surveillance groups. Gleason scores were not assigned in the suspected recurrence group. MR targets located in the anterior prostate had the highest cancer yield (40 of 64, 62.5%) compared with those for the other parts of the prostate (P < .001).

CONCLUSION

In-bore 3-T transperineal MR imaging-guided biopsy, with a mean of 3.7 targets per gland, allowed detection of many clinically relevant cancers, many of which were located anteriorly.

Multiparametric magnetic resonance imaging of the prostate: technical aspects and role in clinical management

The heterogeneity and largely indolent nature of prostate cancer require better tools to avoid overdetection of low-risk disease and improve diagnostic accuracy in high-risk patients. During the last 3 decades, magnetic resonance imaging (MRI) has evolved to become the most accurate imaging technique for prostate cancer detection and staging, with a promising role in risk stratification. Because each MRI technique has advantages and limitations, state of the art of the so-called multiparametric MRI of the prostate is achieved combining anatomical T2-weighted imaging integrated with other techniques in which image contrast is related to the pathophysiology of the disease, such as diffusion-weighted imaging, dynamic contrast-enhanced imaging, and MR spectroscopy. After reviewing this article, readers will understand the clinical challenges in the management of patients with confirmed or suspected prostate cancer, when and how multiparametric MRI of the prostate can provide meaningful information, and how to perform and interpret it.

Evaluation of the PI-RADS scoring system for mpMRI of the prostate: a whole-mount step-section analysis

PURPOSE

Evaluation of the Prostate Imaging Reporting and Data System (PI-RADS) scoring system for classifying multi-parametric magnetic resonance imaging findings of the prostate using whole-mount step-section slides as reference standard.

MATERIALS AND METHODS

Prospective inclusion of 50 consecutive patients with biopsy-proven prostate cancer (PCa). All patients received a multi-parametric MRI of the prostate, consisting of T2-weighted, diffusion-weighted, and dynamic contrast-enhanced MRI. After prostatectomy, all prostates were prepared as whole-mount step-section slides. For each patient, six lesions were predefined on whole-mount step-sections according to a distinct scheme and the corresponding regions were identified on MRI. Each lesion then was scored on MRI according to PI-RADS by an experienced blinded uro-radiologist and compared with histopathological findings.

RESULTS

PCa received significant (p < 0.01) higher overall PI-RADS scores (4.10 ± 0.75) compared with benign changes (2.00 ± 0.74). In the peripheral zone, each single modality score showed good diagnostic accuracy for PCa detection (area under the curve [AUC] > 0.90). When combining all single modality scores, an even higher discriminative ability of PCa detection (AUC = 0.97, 95 % CI 0.95-0.99) could be achieved. In contrast, in the transitional zone, dynamic contrast-enhanced MRI (DCE) showed very low diagnostic accuracy (AUC = 0.60). Regarding tumor malignancy, no high-grade PCa (Gleason >7a) was present at PI-RADS scores <4 and no Gleason 6 PCa at a PI-RADS score of 5.

CONCLUSION

The PI-RADS scoring system showed good diagnostic accuracy: Only PI-RADS 4 and 5 showed high-grade PCa. However, it seems necessary to revise the PI-RADS scoring system concerning DCE in the transitional zone.

A prospective comparison of MRI-US fused targeted biopsy versus systematic ultrasound-guided biopsy for detecting clinically significant prostate cancer in patients on active surveillance

BACKGROUND

In active surveillance (AS) patients: (i) To compare the ability of a multiparametric MRI (mpMRI)-ultrasound biopsy system to detect clinically significant (CS) prostate cancer with systematic 12-core biopsy (R-TRUSBx), and (ii) To assess the predictive value of mpMRI with biopsy as the reference standard.

METHODS

Seventy-two men on AS prospectively underwent 3T mpMRI . MRI-ultrasound fusion biopsy (UroNavBx) and R-TRUSBx was performed. CS cancer was defined using two thresholds: 1) GS ≥ 7 (CS7) and 2) GS = 6 with >50% involvement (GS6). CS cancer detection rates and predictive values were determined.

RESULTS

CS7 cancers were found in 19/72 (26%), 7 (37%) identified by UroNavBx alone, 2 (11%) by R-TRUSBx alone (P = 0.182). UroNav targeted biopsy was 6.3× more likely to yield a core positive for CS7 cancer compared with R-TRUSBx (25% of 141 versus 4% of 874, P < 0.001). Upgrading of GS occurred in 15/72 patients (21%), 13 (87%) detected by UroNavBx and 10 (67%) by R-TRUSBx. The NPV of mpMRI for CS7 cancer was 100%. MRI suspicion level significantly predicted CS cancer on multivariate analysis (OR 3.6, P < 0.001).

CONCLUSION

UroNavBx detected CS cancer with far fewer cores compared with R-TRUSBx, and mpMRI had a perfect negative predictive value in this population.

Multiparametric MRI in biopsy guidance for prostate cancer: fusion-guided

Prostate cancer (PCa) is the most common solid-organ malignancy among American men and the second most deadly. Current guidelines recommend a 12-core systematic biopsy following the finding of an elevated serum prostate-specific antigen (PSA). However, this strategy fails to detect an unacceptably high percentage of clinically significant cancers, leading researchers to develop new, innovative methods to improve the effectiveness of prostate biopsies. Multiparametric-MRI (MP-MRI) has emerged as a promising instrument in identifying suspicious regions within the prostate that require special attention on subsequent biopsy. Fusion platforms, which incorporate the MP-MRI into the biopsy itself and provide active targets within real-time imaging, have shown encouraging results in improving the detection rate of significant cancer. Broader applications of this technology, including MRI-guided focal therapy for prostate cancer, are in early phase trials.

Prostate cancer: performance characteristics of combined T₂W and DW-MRI scoring in the setting of template transperineal re-biopsy using MR-TRUS fusion

OBJECTIVES

To measure the performance characteristics of combined T2-weighted (T₂W) and diffusion-weighted (DW) magnetic resonance imaging (MRI) suspicion scoring prior to MR-transrectal ultrasound (TRUS) fusion template transperineal (TTP) re-biopsy.

METHODS

Thirty-nine patients referred for prostate re-biopsy, with prior MRI examinations, were retrospectively included. The MR images, including T₂W and DW-MRI, had been independently evaluated prospectively by two radiologists using a structured scoring system. An MR-TRUS fusion TTP re-biopsy was used for MR target and non-targeted biopsy cores. Targeting performance and correlation with disease status were evaluated on a per-patient and per-region basis.

RESULTS

The cancer yield was 41% (16/39 patients). MR targeting accurately detected the disease in 12/16 (75%) cancerous patients and missed the disease in 4/16 (25%) patients, all with Gleason 3 + 3 disease. There was a significant relationship (P < 0.01) between MR suspicion score and the significance of cancer. Reader 1 had significantly higher sensitivity in the transition zone (TZ; 0.84) compared with the peripheral zone (PZ; 0.32) (P = 0.04). Inter-reader agreement was moderate for the PZ and substantial for the TZ.

CONCLUSIONS

MRI targeting is beneficial in the setting of TTP MR-TRUS fusion re-biopsy and MR suspicion score relates to prostate cancer clinical significance. A T₂W and DW-MRI structured scoring system results in good inter-reader agreement in this setting.

KEY POINTS

• Pre-biopsy MRI aids the detection of high significance cancer during prostate re-biopsy. • MRI suspicion level correlates with the clinical significance of prostate cancer detected. • T₂W and DW-MRI structured scoring of pre-biopsy MRI permits good inter-reader agreement.