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

The diagnostic accuracy of multiparametric magnetic resonance imaging before biopsy in the detection of prostate cancer

OBJECTIVES

To determine the extent to which clinically significant prostate cancer (csPCa) can be detected in a routine National Health Service setting in men with no previous biopsy, when multiparametric magnetic resonance imaging (mpMRI) is introduced into the diagnostic pathway.

PATIENTS AND METHODS

In all, 1 090 mpMRIs were performed between July 2013 and April 2016 in biopsy-naïve men with an abnormal prostate-specific antigen level and/or digital rectal examination. Data were collected from patient records at the Royal Devon and Exeter NHS Foundation Trust. mpMRI Prostate Imaging Reporting and Data System (PI-RADS) scores were compared to transperineal or transrectal ultrasonography (TRUS)-guided biopsy findings as the reference standard. csPCa was defined as Gleason score of ≥3+4. The diagnostic accuracy of mpMRI was also assessed.

RESULTS

The mpMRI was interpretable in 1 023 men and 792 underwent biopsy, of which 106 were transperineal. The median number of cores taken in transperineal and TRUS-guided biopsy were 10 and 6, respectively. The detection rate of csPCa was 37%; csPCa rose from 15% of PI-RADS 1 and 2 to 86% of PI-RADS 5. The sensitivity, negative predictive value, specificity, and positive predictive value were 82%, 85%, 59% and 54%, respectively. The study is limited by its retrospective nature and lack of reporting of follow-up for 'missed cancers'. Men with low mpMRI PI-RADS were also less likely to undergo biopsy. Whilst this selection bias may overestimate the detection rate of csPCa, this reflects the shared decisions patients and clinicians make in day-to-day practice outside of research centres.

CONCLUSION

In a routine clinical setting, the higher the mpMRI PI-RADS, the greater the detection rate of csPCa in biopsy-naïve men. A normal mpMRI does not exclude csPCa; however, mpMRI may have utility in informing shared-decision making on whether to proceed to biopsy and subsequent treatment.

Cost and efficacy comparison of five prostate biopsy modalities: a platform for integrating cost into novel-platform comparative research

BACKGROUND

The cornerstone of prostate cancer diagnosis remains the transrectal ultrasound-guided biopsy (TRUS-BX), which most frequently occurs in the office setting under local anesthesia. However, there are now other techniques of prostate biopsy aimed at improving outcomes such as patient comfort, significant cancer detection, and infectious complications. The purpose of the present study is to compare the cost and efficacy outcomes of five different approaches.

METHODS

We compared the comprehensive costs of a random sample size of 20-30 cases from each of the following: (1) local anesthesia TRUS-BX (reference), (2) sedation TRUS-BX, (3) general anesthesia transperineal template biopsy (TP), (4) sedation MRI-TRUS fusion biopsy (FB), and (5) sedation in-bore MRI biopsy (IB-MRI). Cost categories included pre-procedure, anesthesia pharmacy and recovery, and the technical/professional costs from urology, radiology, and pathology services. For procedure outcomes, we compared the larger cohorts of TRUS-BX, TP, and FB in terms of indication, cancer yield, and downstream decision impact.

RESULTS

Compared with standard TRUS-BX, the total costs of sedation TRUS-BX, TP, FB, and IB-MRI increased significantly ×1.9 (90%), ×2.5 (153%), ×2.5 (150%), and ×2.2 (125%), respectively (p < 0.001). Although there was no statistical difference between the total costs of TP, FB, and IB-MRI, these costs were significantly higher than those of TRUS-BX under either local anesthesia or sedation (p < 0.05). The cost of TRUS-BX under sedation was significantly higher than that of TRUS-BX under local anesthesia (p < 0.001). Compared to TRUS-BX, more significant cancers were detected in FB (16% vs. 36%) and TP (16% vs. 34%) groups (p < 0.001).

CONCLUSIONS

Compared with standard TRUS-BX, the additions of imaging, sedation anesthesia, and transperineal template increase costs significantly, and can be considered along with known improvements in accuracy and side effects. Ongoing efforts to combine imaging and transperineal biopsy, especially in an outpatient/local anesthesia setting may lead to a higher cost/benefit.

Defining the target prior to prostate fusion biopsy: the effect of MRI reporting on cancer detection

PURPOSE

Definition of targets in multiparametric MRI (mpMRI) prior to MRI/TRUS fusion prostate biopsy either by urologist or radiologist, as a prose report or by illustration is crucial for accurate targeted biopsies (TB). The objective was to analyze the effect of MRI reporting on target definition and cancer detection.

METHODS

202 patients underwent MRI/TRUS fusion biopsy with Artemis™ (Eigen, USA). mpMRI results were submitted in written form to urologists, who marked the targets in the proprietary software. An expert uroradiologist reviewed and marked mpMRI targets blinded to biopsy data. We compared number, localization and volume of targets between the observers and analyzed whether variations impaired TB results by bivariate and logistic regression models.

RESULTS

Interobserver variability was moderate regarding number and low regarding localization of targets. Urologists overestimated target volumes significantly compared to radiologists (p = 0.045) and matching target volume between both observers was only 43.9%. Overall cancer detection rate was 69.8 and 52.0% by TB. A higher matching target volume was a significant predictor of cancer in TB (p < 0.001). Logistic regression revealed prostate volume and PI-RADS as independent predictors. Defining targets in incorrect T2w slices in the cranio-caudal axis are one presumable reason for missing cancer in TB.

CONCLUSIONS

A high concordance of the target definition between radiologist and urologist is mandatory for accurate TB. Optimized ROI definition is recommended to improve TB results, preferably as contouring in MRI sequences by the radiologist or, if not feasible, by precise MRI reports including specific localization in sequence and slice as well as an illustration. High prostate volume and low PI-RADS score have to be considered as limiting factors for target definition.

Imaging biomarkers in oncology: Basics and application to MRI

Cancer remains a global killer alongside cardiovascular disease. A better understanding of cancer biology has transformed its management with an increasing emphasis on a personalized approach, so-called "precision cancer medicine." Imaging has a key role to play in the management of cancer patients. Imaging biomarkers that objectively inform on tumor biology, the tumor environment, and tumor changes in response to an intervention complement genomic and molecular diagnostics. In this review we describe the key principles for imaging biomarker development and discuss the current status with respect to magnetic resonance imaging (MRI).

LEVEL OF EVIDENCE

5 TECHNICAL EFFICACY: Stage 5 J. Magn. Reson. Imaging 2018;48:13-26.

Multiparametric MRI reporting using Prostate Imaging Reporting and Data System version 2.0 (PI-RADSv2) retains clinical efficacy in a predominantly post-biopsy patient population

Objective

To evaluate the efficacy of multiparametric magnetic resonance imaging (mp-MRI) using Prostate Imaging Reporting and Data System version 2.0 (PI-RADSv2) definitions in detecting organ-confined prostate cancer.

Methods

All patients who underwent radical prostatectomy between January 1, 2014 and December 30, 2014 were identified. All underwent mp-MRI within 180 days before surgery. Those with prior pelvic irradiation or androgen deprivation therapy were excluded. Fully embedded, whole-mount histopathology was centrally reviewed and correlated with imaging for tumour location, Gleason score (GS) and stage.

Results

There were 39 patients included, of which 35 (90%) had mp-MRI done post-biopsy. A total of 93 cancer foci were identified on whole-mount pathology, of which mp-MRI detected 63 (68%). Of those detected by mp-MRI, 14 were PI-RADS 3 (n = 6 for GS 6, n = 8 for GS 7, no GS ≥ 8) and 49 were PI-RADS 4–5 (n = 7 for GS 6, n = 33 for GS 7, and n = 9 for GS ≥ 8). There were 30 (32%) cancer foci missed by mp-MRI (n = 15 for GS 6, n = 13 for GS 7 and n = 2 for GS ≥ 8). A lesion classified as PI-RADS 4–5 predicted a higher grade cancer on pathology as compared to PI-RADS 3 (for GS 7 lesions, odds ratio [OR] = 3.53, 95% CI: 0.93–13.45, p = 0.064). The mp-MRI size detection limit was 20 mm² and 100 mm² for 50% and 75% probability of cancer, respectively. In associating with radiological and pathologic stage, the weighted Kappa value was 0.69 (p < 0.0001). The sensitivity and positive predictive values for this study were 68% (95% CI: 57%–77%) and 78% (95% CI: 67%–86%), respectively.

Conclusion

In this predominantly post-biopsy cohort, mp-MRI using PI-RADSv2 reporting has a reasonably high diagnostic accuracy in detecting clinically significant prostate cancer.

Assessment of the Diagnostic Accuracy of Biparametric Magnetic Resonance Imaging for Prostate Cancer in Biopsy-Naive Men: The Biparametric MRI for Detection of Prostate Cancer (BIDOC) Study

IMPORTANCE

Multiparametric magnetic resonance imaging (MRI) enhances detection and risk stratification for significant prostate cancer but is time-consuming (approximately 40 minutes) and expensive. Rapid and simpler (approximately 15-minute) biparametric MRI (bpMRI) using fewer scan sequences could be implemented as a prostate MRI triage test on a larger scale before performing biopsies.

OBJECTIVES

To assess the diagnostic accuracy and negative predictive value (NPV) of a novel bpMRI method in biopsy-naive men in detecting and ruling out significant prostate cancer in confirmatory biopsies.

DESIGN, SETTING, AND PARTICIPANTS

A single-institutional, paired, prospective cohort study of biopsy-naive men with clinical suspicion of prostate cancer from November 1, 2015, to June 15, 2017.

INTERVENTIONS

All patients underwent bpMRI (T2-weighted and diffusion-weighted imaging) followed by standard transrectal ultrasound-guided biopsies (all men) and targeted biopsies of men with suspicious bpMRI findings.

MAIN OUTCOMES AND MEASURES

Suspicion grades of bpMRI, biopsy results, and NPV of bpMRI were evaluated for detection of or ruling out significant prostate cancer (Gleason score ≥4 + 3 or maximum cancerous core length >50% for Gleason score 3 + 4). We compared the diagnostic performance of standard biopsies in all men vs standard plus targeted (combined) biopsies restricted to men with suspicious bpMRI findings. The reference standard was combined biopsy results from all men.

RESULTS

A total of 1020 men were enrolled, with a median age of 67 years (interquartile range, 61-71 years) and a median prostate-specific antigen level of 8.0 ng/mL (interquartile range, 5.7-13.0 ng/mL). Combined biopsies detected any and significant prostate cancer in 655 of 1020 men (64%) and 404 of 1020 men (40%), respectively. Restricting combined biopsies to men with suspicious bpMRI findings meant 305 of 1020 men (30%) with low-suspicious bpMRIs could avoid prostate biopsies (biopsy in 715 men with suspicious bpMRIs vs all 1020 men who required standard biopsies [70%]; P < .001). Significant prostate cancer diagnoses were improved by 11% (396 vs 351 men; P < .001), and insignificant prostate cancer diagnoses were reduced by 40% (173 vs 288 men; P < .001) compared with our current diagnostic standard, standard biopsies alone in all men. The NPV of bpMRI findings in ruling out significant prostate cancer was 97% (95% CI, 95%-99%).

CONCLUSIONS AND RELEVANCE

Low-suspicion bpMRI has a high NPV in ruling out significant prostate cancer in biopsy-naive men. Using a simple and rapid bpMRI method as a triage test seems to improve risk stratification and may be used to exclude aggressive disease and avoid unnecessary biopsies with its inherent risks. Future studies are needed to fully explore its role in clinical prostate cancer management.

Cancer detection rate of prebiopsy MRI with subsequent systematic and targeted biopsy are superior to non-targeting systematic biopsy without MRI in biopsy naïve patients: a retrospective cohort study

Background

To determine whether prebiopsy multiparametric magnetic resonance imaging (mpMRI) with subsequent systematic plus targeted biopsies for suspicious lesions improve prostate cancer detection compared with standard non-targeting systematic biopsies without mpMRI in biopsy-naïve patients.

Methods

Patients who underwent their first prostate biopsy due to suspicion of prostate cancer were analyzed retrospectively to compare the biopsy outcomes between patients who received prebiopsy mpMRI (215 patients) and those who did not (281 patients). mpMRI was performed to determine pre-biopsy likelihood of the presence of prostate cancer using a three-point scale (1 = low level of suspicion, 2 = equivocal, and 3 = high level of suspicion). Systematic biopsies were performed in both groups. Targeted biopsies were added for a high level of suspicious lesions on mpMRI. All biopsies were performed by transperineal biopsy technique. After biopsy, Prostate Imaging Reporting and Data System ver. 2 (PIRADS-2) scoring was performed to describe the mpMRI findings and predictive value of PIRADS-2 was evaluated.

Results

The detection rate of total and clinically significant prostate cancer was significantly higher in patients who received prebiopsy mpMRI than in those who did not (55.3 and 46.0% vs. 42.0 and 35.2%, respectively; p = 0.004 and p = 0.016). The clinically insignificant prostate cancer detection rate was similar between the two groups (9.3% vs. 6.8%; p = 0.32). Of 86 patients who underwent systematic plus targeted biopsy in the MRI cohort and were diagnosed with prostate cancer, seven patients were detected by addition of targeted biopsy whereas 29 patients were missed by targeted biopsy but detected by systematic biopsy. There was a correlation between the PIRADS-2 and prostate cancer detection rate, and a receiver-operator curve analysis yielded an area under the curve of 0.801 (p <  0.0001).

Conclusions

Prebiopsy mpMRI with subsequent systematic plus targeted biopsies for suspicious lesions can yield a higher cancer detection rate than non-targeting systematic biopsies. PIRADS-2 scoring is useful for predicting the biopsy outcome.

PI-RADS v2: Current standing and future outlook

The Prostate Imaging-Reporting and Data System (PI-RADS) was created in 2012 to establish standardization in prostate multiparametric magnetic resonance imaging (mpMRI) acquisition, interpretation, and reporting. In hopes of improving upon some of the PI-RADS v1 shortcomings, the PI-RADS Steering Committee released PI-RADS v2 in 2015. This paper reviews the accuracy, interobserver agreement, and clinical outcomes of PI-RADS v2 and comments on the limitations of the current literature. Overall, PI-RADS v2 shows improved sensitivity and similar specificity compared to PI-RADS v1. However, concerns exist regarding interobserver agreement and the heterogeneity of the study methodology.

[PI-RADS 2.0 for Prostate MRI]

The PI-RADS 2.0 classification was established by an international collaboration of the European Society of Urogenital Radiology (ESUR), the American College of Radiology (ACR), and AdMetech Foundation to globally standardize the acquisition and interpretation of multiparametric prostate magnetic resonance imaging (MRI). The PI-RADS 2.0 aims to improve the detection, localization, staging and risk stratification of patients with suspected or histologically confirmed prostate cancer. Suspicious areas on T2-weighted (T2w) MRI, diffusion-weighted MRI (DWI) and dynamic contrast-enhanced MRI (DCE-MRI) were assessed for the presence of a clinically significant prostate cancer with scale from 1 to 5 with 5 being most likely to represent clinically significant prostate cancer. The dominant sequence to detect significant prostate cancer in the peripheral zone is DWI and for the transition zone T2w images. For the local staging of prostate cancer criteria for the assessment of an extracapsular growth were formulated.

Multiparametric (mp) MRI of prostate cancer

Prostate cancer (PCa) is one of the most prevalent cancers in men. A large number of men are detected with PCa; however, the clinical behavior ranges from low-grade indolent tumors that never develop into a clinically significant disease to aggressive, invasive tumors that may rapidly progress to metastatic disease. The challenges in clinical management of PCa are at levels of screening, diagnosis, treatment, and follow-up after treatment. Magnetic resonance imaging (MRI) methods have shown a potential role in detection, localization, staging, assessment of aggressiveness, targeting biopsies, etc. in PCa patients. Multiparametric MRI (mpMRI) is emerging as a better option compared to the individual imaging methods used in the evaluation of PCa. There are attempts to improve the reproducibility and reliability of mpMRI by using an objective scoring system proposed in the prostate imaging reporting and data system (PIRADS) for standardized reporting. Prebiopsy mpMRI may be used to detect PCa in men with elevated prostate-specific antigen or abnormal digital rectal examination and to enable targeted biopsies. mpMRI can also be used to decide on clinical management of patients, for example active surveillance, and may help in detecting only the pathology that requires detection. It can potentially not only guide patient selection for initial and repeat biopsy but also reduce false-negative biopsies. This review presents a description of the MR methods most commonly applied for investigations of prostate. The anatomical, functional and metabolic parameters obtained from these MR methods are discussed with regard to their physical basis and their contribution to mpMRI investigations of PCa.

The combination of prostate imaging reporting and data system version 2 (PI-RADS v2) and periprostatic fat thickness on multi-parametric MRI to predict the presence of prostate cancer

PURPOSE

To evaluate the auxiliary effectiveness of periprostatic fat thickness (PPFT) on multi-parametric magnetic resonance imaging (mp-MRI) to Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) in predicting the presence of prostate cancer (PCa) and high-grade prostate cancer (HGPCa, Gleason Score ≥ 7).

RESULTS

Overall, there were 371 patients (54.3%) with PCa and 292 patients (42.8%) with HGPCa. The mean value of PPFT was 4.04 mm. Multivariate analysis revealed that age, prostatic specific antigen (PSA), volume, PI-RADS score, and PPFT were independent predictors of PCa. All factors plus abnormal digital rectal exam were independent predictors of HGPCa. In addition, the PPFT was the independent predictor of PCa (Odds ratio [OR] 2.56, p = 0.004) and HGPCa (OR 2.70, p = 0.014) for subjects with PI-RADS grade 3. The present two nomograms based on multivariate analysis outperformed the single PI-RADS in aspects of predicting accuracy for PCa (area under the curve: 0.922 vs. 0.883, p = 0.029) and HGPCa (0.919 vs. 0.873, p = 0.007). Decision-curve analysis also indicated the favorable clinical utility of the present two nomograms.

MATERIALS AND METHODS

The clinical data of 683 patients who received transrectal ultrasound guided biopsy and prior mp-MRI were reviewed. PPFT was measured as the shortest perpendicular distance from the pubic symphysis to the prostate on MRI. Univariate and multivariate analyses were performed to determine the independent predictors of PCa and HGPCa. We also constructed two nomograms for predicting PCa and HGPCa based on the logistic regression.

CONCLUSION

The PPFT on mp-MRI is an independent predictor of PCa and HGPCa, notably for patients with PI-RADS grade 3. The nomograms incorporated predictors of PPFT and PI-RADS demonstrated good predictive performance.

Poor reproducibility of PIRADS score in two multiparametric MRIs before biopsy in men with elevated PSA

Purpose

Since January 2015, all men referred to urologists in Norway due to elevated PSA or other suspicion of prostate cancer underwent multiparametric MRI (mpMRI) before prostate biopsy. At our hospital, patients and the initial MRI were assessed by an urologist and if deemed necessary, patients were referred to another institution for MR/US fusion biopsies. Before MR/US biopsy, patients underwent a second mpMRI. Since we noticed disagreement of these two mpMRIs before biopsy, we retrospectively assessed the level of agreement between the two mpMRIs from the two institutions.

Methods

During the first 6 months of 2015, 292 patients were referred to our outpatient clinic. We referred 126 patients of these to the other institution for MR/US fusion biopsy. The 2 mpMRIs were performed within 4 weeks. We analyzed MR reports and schematics for number of lesions and highest PIRADS score per side of the prostate and histological result of the biopsies. Bland–Altman’s plot was used to compare the level of agreement between the two mpMRIs of the same patient before biopsy.

Results

There was a poor level of agreement between the two mpMRIs and a statistically significant difference in PIRADS scores. Regression analysis showed that there was no proportional or systematic bias.

Conclusion

In unselected patients with elevated PSA, there seems to be a significant variation of mpMRI results across institutions. The PIRADS scoring system needs to be validated with regards to MR equipment, mpMRI protocols and inter-reader variability of radiologists.

Multiparametric MRI in men with clinical suspicion of prostate cancer undergoing repeat biopsy: a prospective comparison with clinical findings and histopathology

Background Multiparametric magnetic resonance imaging (mpMRI) can improve detection of clinically significant prostate cancer (csPCa). Purpose To compare mpMRI score subgroups to systematic transrectal ultrasound-guided biopsies (TRUS_bx) and prostate-specific antigen (PSA)-based findings for detection of csPCa in men undergoing repeat biopsies. Material and Methods MpMRI was performed prior to re-biopsy in 289 prospectively enrolled patients. All underwent repeat TRUS_bx followed by targeted biopsies (MRI_TB) of any mpMRI-identified lesion. MpMRI suspicion grade, PSA level, and density (PSAd) were compared with biopsy results and further matched to the radical prostatectomy (RP) specimen if available. Results PCa was detected in 128/289 (44%) patients with median age, PSA, and prior negative TRUS_bx of 64 (interquartile range [IQR] = 59-67), 12.0 ng/mL (IQR = 8.3-19.1), and 2 (IQR = 1-3), respectively. TRUS_bx detected PCa in 108/289 (37%) patients, of which 49 (45%) had insignificant cancer. MRI_TB was performed in 271/289 (94%) patients and detected PCa in 96 (35%) with 78 (81%) having csPCa. MpMRI scores showed a high association between suspicion level and biopsy results on both lesion and patient level ( P < 0.001). MpMRI was better than PSA and PSAd ( P < 0.001) to identify patients with missed csPCa. In total, 64/128 (50%) patients underwent RP; 60/64 had csPCa. MpMRI was significantly better in predicting csPCa on RP compared with TRUS_bx ( P = 0.019) as MRI_TB and TRUS_bx correctly identified 47/60 (78%) and 35/60 (58%) patients, respectively. Conclusion MpMRI improves detection of missed csPCa and suspicion scores correlate well with biopsy and RP results on both patient and lesion level.

Novel application of three-dimensional shear wave elastography in the detection of clinically significant prostate cancer

The present study evaluated three-dimensional shear wave elastography (3D SWE) in the detection of clinically significant prostate cancer. Clinically significant prostate cancer was defined by a minimum of one biopsy core with a Gleason score of 3+4 or 6 with a maximum cancer core length >4 mm. Patients with serum prostate-specific antigen levels of 4.0-20.0 ng/ml who were suspected of having prostate cancer from multi-parametric magnetic resonance imaging (mpMRI) were prospectively recruited. The 3D SWE was performed pre-biopsy, after which patients underwent MRI-transrectal ultrasound image-guided targeted biopsies for cancer-suspicious lesions and 12-core systematic biopsies. The pathological biopsy results were compared with the mpMRI and 3D SWE images. A total of 12 patients who were suspected of having significant cancer on mpMRI were included. The median pre-biopsy PSA value was 5.65 ng/ml. Of the 12 patients, 10 patients were diagnosed as having prostate cancer. In the targeted biopsy lesions, there was a significant difference in Young's modulus between the cancer-detected area (median 64.1 kPa, n=20) and undetected area (median 30.8 kPa, n=8; P<0.0001). On evaluation of receiver operating characteristics, a cut-off value of the Young's modulus of 41.0 kPa was used for the detection of clinically significant cancer, with which the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of cancer detection were 58, 97, 86 and 87%, respectively. When combining this cut-off tissue elasticity value with Prostate Imaging Reporting and Data System (PI-RADS) scores, the sensitivity, specificity, positive predictive value and negative predictive value of cancer detection were improved to 70, 98, 91 and 92%, respectively. In the cancer-detected lesions, a significant correlation was identified between the tissue elasticity value of the lesions and Gleason score (r=0.898, P<0.0001). In conclusion, PI-RADS combined with measurement of Young's modulus by 3D SWE may improve the diagnosis of clinically significant prostate cancer.

Assessment of Needle Tip Deflection During Transrectal Guided Prostate Biopsy: Implications for Targeted Biopsies

OBJECTIVES

To measure needle tip deflection during transrectal ultrasound (TRUS) prostate biopsy and evaluate predictors for needle tip deflection.

MATERIALS AND METHODS

Analysis of 568 prostate biopsies obtained from 51 consecutive patients who underwent a standard 12-core TRUS guided prostate biopsy. TRUS guided prostate biopsies were performed using BK flex500, with a side-fire biplane probe. Each biopsy core image was captured and clinical data were recorded prospectively. The angle between the expected trajectory of the needle and actual needle course was measured using the longitudinal view of the captured image. The distance between expected and actual needle tip was calculated. We measured median and interquartile needle tip deflection rate stratified by side and location (apex, midgland, base). Univariable and multivariable linear regressions analysis were performed.

RESULTS

The overall median needle tip deflection was 1.77 mm (IQR 1.35-2.47). Location did not significantly alter needle deflection measurements. On multivariable linear regression analysis, higher prostate volume (B = 0.007 95%, CI 0.004, 0.011; p < 0.001) and the right sided biopsy (B = 0.191 95%, CI 0.047, 0.336; p = 0.010) emerged as predictors of higher needle tip deflection.

CONCLUSIONS

To the best of our knowledge this is the first study to measure needle tip deflection during TRUS guided prostate biopsies. We demonstrated that larger prostate size and biopsy side may affect the accuracy of biopsies. These results may have clinical implication to those performing targeted biopsies.

Repeat multiparametric MRI in prostate cancer patients on active surveillance

Introduction

This study was conducted to describe the changes in repeat multiparametric MRI (mpMRI) occurring in prostate cancer (PCa) patients during active surveillance (AS), and to study possible associations between mpMRI-related parameters in predicting prostate biopsy (Bx) Gleason score (GS) upgrading >3+3 and protocol-based treatment change (TC).

Materials and methods

The study cohort consisted of 76 AS patients with GS 3+3 PCa and at least two consecutive mpMRIs of the prostate performed between 2006–2015. Patients were followed according to the Prostate Cancer Research International Active Surveillance (PRIAS) protocol and an additional mpMRI. The primary end points were GS upgrading (GU) (>3+3) in protocol-based Bxs and protocol-based TC.

Results

Out of 76 patients, 53 (69%) had progression (PIRADS upgrade, size increase or new lesion[s]), while 18 (24%) had radiologically stable disease, and 5 (7%) had regression (PIRADS or size decrease, disappearance of lesion[s]) in repeat mpMRIs during AS. PIRADS scores of 4–5 in the initial mpMRI were associated with GU (p = 0.008) and protocol-based TC (p = 0.009). Tumour progression on repeat mpMRIs was associated with TC (p = 0.045) but not with GU (p = 1.00). PIRADS scores of 4–5 predict GU (sensitivity 0.80 [95% confidence interval (CI); 0.51–0.95, specificity 0.62 [95% CI; 0.52–0.77]) with PPV and NPV values of 0.34 (95% CI; 0.21–0.55) and 0.93 (95% CI; 0.80–0.98), respectively.

Conclusion

mpMRI is a useful tool not only to select but also to monitor PCa patients on AS.

Evaluating the performance of PI-RADS v2 in the non-academic setting

PURPOSE

To evaluate the utility of PI-RADS v2 to diagnose clinically significant prostate cancer (CS-PCa) with magnetic resonance ultrasound (MR/US) fusion-guided prostate biopsies in the non-academic setting.

MATERIALS/METHODS

Retrospective analysis of men whom underwent prostate multiparametric MRI and subsequent MR/US fusion biopsies at a single non-academic center from 11/2014 to 3/2016. Prostate MRIs were performed on a 3-Tesla scanner with a surface body coil. The Prostate Imaging Reporting and Data System (PI-RADS) v2 scoring algorithm was utilized and MR/US fusion biopsies were performed in selected cases. Mixed effect logistic regression analyses and receiver-operating characteristic (ROC) curves were performed on PI-RADS v2 alone and combined with PSA density (PSAD) to predict CS-PCa.

RESULTS

170 patients underwent prostate MRI with 282 PI-RADS lesions. MR/US fusion diagnosed 71 CS-PCa, 33 Gleason score 3+3, and 168 negative. PI-RADS v2 score is a statistically significant predictor of CS-PCa (P < 0.001). For each one-point increase in the overall PI-RADS v2 score, the odds of having CS-PCa increases by 4.2 (95% CI 2.2-8.3). The area under the ROC curve for PI-RADS v2 is 0.69 (95% CI 0.63-0.76) and for PI-RADS v2 + PSAD is 0.76 (95% CI 0.69-0.82), statistically higher than PI-RADS v2 alone (P < 0.001). The rate of CS-PCa was about twice higher in men with high PSAD (≥0.15) compared to men with low PSAD (<0.15) when a PI-RADS 4 or 5 lesion was detected (P = 0.005).

CONCLUSION

PI-RADS v2 is a strong predictor of CS-PCa in the non-academic setting and can be further strengthened when utilized with PSA density.

Targeted 11C-choline PET-CT/TRUS software fusion-guided prostate biopsy in men with persistently elevated PSA and negative mpMRI after previous negative biopsy

Background

We evaluated the feasibility and accuracy of 11C–choline PET-CT/TRUS fusion-guided prostate biopsy in men with persistently elevated PSA and negative mpMRI or contraindication to MRI, after previous negative biopsy. Clinical data were part of a prospective on-going observational clinical study: “Diagnostic accuracy of target mpMRI/US fusion biopsy in patients with suspected prostate cancer after initial negative biopsy”. Patients with a negative biopsy and negative mpMRI (PI-RADS v.2 < 3) or absolute contraindications to MRI and persistently elevated PSA, were included. All patients underwent 11C–choline PET with dedicated acquisition of the pelvis and PET-CT/TRUS-guided prostate biopsy by Bio-Jet™ fusion system (D&K Technologies, Germany). The primary endpoint was to assess the accuracy of 11C–choline PET-CT to determine the presence and the topographical distribution of PCa.

Results

Overall, 15 patients (median age 71 yrs. ± 8.89; tPSA 13.5 ng/ml ± 4.3) were analysed. Fourteen had a positive PET scan, which revealed 30 lesions. PCa was detected in 7/15 patients (46.7%) and four patients presented a clinically significant PCa: GS > 6. Over 58 cores, 25 (43.1%) were positive. No statistically significant difference in terms of mean and median values for SUVmax and SUVratio between benign and malignant lesions was found. PCa lesions with GS 3 + 3 (n = 3) showed a median SUVmax and SUVratio of 4.01 and 1.46, compared to 5.45 and 1.57, respectively for lesions with GS >6 (n = 4).

Conclusion

Software PET-CT/TRUS fusion-guided target biopsy could be a diagnostic alternative in patients with a suspected primary PCa and negative mpMRI, but its specificity appeared low.

A systematic review on multiparametric MR imaging in prostate cancer detection

BACKGROUND

Literature data suggest that multi-parametric Magnetic Resonance Imaging (MRI), including morphologic T2-weigthed images (T2-MRI) and functional approaches such as Dynamic Contrast Enhanced-MRI (DCE-MRI), Diffusion Weighted Imaging (DWI) and Magnetic Resonance Spectroscopic Imaging (MRSI), give an added value in the prostate cancer localization and local staging.

METHODS

We performed a systematic review of literature about the role and the potentiality of morphological and functional MRI in prostate cancer, also in a multimodal / multiparametric approach, and we reported the diagnostic accuracy results for different imaging modalities and for different MR coil settings: endorectal coil (ERC) and phased array coil (PAC). Forest plots and receiver operating characteristic curves were performed. Risk of bias and the applicability at study level were calculated.

RESULTS

Thirty three papers were identified for the systematic review. Sensitivity and specificity values were, respectively, for T2-MRI of 75% and of 60%, for DCE-MRI of 80% and of 72%, for MRSI of 89% and of 69%, for combined T2-MRI and DCE-MRI of 87% and of 46%, for combined T2-MRI and MRSI of 79% and of 57%, for combined T2-MRI, DWI and DCE-MRI of 81% and of 84%, and for combined MRSI and DCE-MRI of 83% and of 83%. For MRI studies performed with ERC we obtained a pooled sensitivity and specificity of 81% and of 66% while the pooled values for MRI studies performed with PAC were of 78% and of 64%, respectively (p>0.05 at McNemar test). No studies were excluded from the analysis based on the quality assessment.

CONCLUSIONS

ERC use yielded no additional benefit in terms of prostate cancer detection accuracy compared to multi-channel PAC use (71% versus 68%) while the use of additional functional imaging techniques (DCE-MRI, DWI and MRSI) in a multiparametric MRI protocol improves the accuracy of prostate cancer detection allowing both the early cure and the guidance of biopsy.

Computer aided detection in prostate cancer diagnostics: A promising alternative to biopsy? A retrospective study from 104 lesions with histological ground truth

BACKGROUND

Prostate cancer (PCa) diagnosis by means of multiparametric magnetic resonance imaging (mpMRI) is a current challenge for the development of computer-aided detection (CAD) tools. An innovative CAD-software (Watson Elementary™) was proposed to achieve high sensitivity and specificity, as well as to allege a correlate to Gleason grade.

AIM/OBJECTIVE

To assess the performance of Watson Elementary™ in automated PCa diagnosis in our hospital´s database of MRI-guided prostate biopsies.

METHODS

The evaluation was retrospective for 104 lesions (47 PCa, 57 benign) from 79, 64.61±6.64 year old patients using 3T T2-weighted imaging, Apparent Diffusion Coefficient (ADC) maps and dynamic contrast enhancement series. Watson Elementary™ utilizes signal intensity, diffusion properties and kinetic profile to compute a proportional Gleason grade predictor, termed Malignancy Attention Index (MAI). The analysis focused on (i) the CAD sensitivity and specificity to classify suspect lesions and (ii) the MAI correlation with the histopathological ground truth.

RESULTS

The software revealed a sensitivity of 46.80% for PCa classification. The specificity for PCa was found to be 75.43% with a positive predictive value of 61.11%, a negative predictive value of 63.23% and a false discovery rate of 38.89%. CAD classified PCa and benign lesions with equal probability (P 0.06, χ2 test). Accordingly, receiver operating characteristic analysis suggests a poor predictive value for MAI with an area under curve of 0.65 (P 0.02), which is not superior to the performance of board certified observers. Moreover, MAI revealed no significant correlation with Gleason grade (P 0.60, Pearson´s correlation).

CONCLUSION

The tested CAD software for mpMRI analysis was a weak PCa biomarker in this dataset. Targeted prostate biopsy and histology remains the gold standard for prostate cancer diagnosis.

Validation of Prostate Imaging-Reporting and Data System Version 2: A Retrospective Analysis

PURPOSE

Use of magnetic resonance imaging (MRI)/transrectal ultrasound fusion biopsies to determine the accuracy of multiparametric MRI (mpMRI), using Prostate Imaging-Reporting and Data System version 2 (PI-RADSv2), for detecting clinically significant prostate cancer in the overall gland and specifically the peripheral zone (PZ) and transitional zone (TZ).

METHODS

A retrospective analysis of patients who underwent fusion biopsy identified 137 men with 231 prostate lesions was approved by the Institutional Review Board. Subjects initially classified under PI-RADSv1 criteria were regraded using PI-RADSv2 by a radiologist blinded to PI-RADSv1 score and biopsy results. Spearman correlation, chi-squared, and logistic regression analysis were performed.

RESULTS

There was positive correlation between PI-RADSv2 and Gleason scores (P < 0.001). In the PZ, mpMRI demonstrated 100% sensitivity, 100% negative predictive value, and 35.9% positive predictive value, compared to 100%, 100%, and 27.1%, respectively, for TZ lesions. When predicting clinically significant prostate cancer, the PI-RADSv2 area under the curve for TZ lesions was 0.844 (95% CI: 0.753-0.935, P < 0.001) and 0.769 (95% CI: 0.684-0.854, P < 0.001) for PZ lesions. Combining PI-RADSv2 with additional risk factors (body mass index, prostate-specific antigen density, digital rectal examination) improved the area under curve.

CONCLUSIONS

PI-RADSv2 achieves excellent sensitivity and negative predictive value for both PZ and TZ lesions.

Development and internal validation of prediction models for biochemical failure and composite failure after focal salvage high intensity focused ultrasound for local radiorecurrent prostate cancer: Presentation of risk scores for individual patient prognoses

PURPOSE

Patient selection for focal salvage remains difficult. Therefore, we developed and internally validated prediction models for biochemical failure (BF) and a composite endpoint (CE) following focal salvage high intensity focused ultrasound (HIFU) for radiorecurrent prostate cancer.

MATERIALS AND METHODS

A prospective HIFU registry identified 150 cases (November 2006-August 2015). Recurrence was assessed with multiparametric magnetic resonance imaging (MRI) combined with template prostate mapping biopsies, targeted biopsies, or systematic transrectal ultrasound-guided biopsies. Metastatic disease was ruled out with a positron emission tomography-computed tomography and a bone scan. Focal salvage HIFU consisted of quadrant-ablation, hemi-ablation, or index-lesion ablation. Cox-regression was used for BF (Phoenix-definition) and CE (BF/MRI+/biopsies+/local or systemic treatment/metastases+/prostate cancer specific mortality+). Internal validation was performed using bootstrap resampling (500 datasets) after which C-statistic and hazard ratios were adjusted. Models were calibrated and risk scores created.

RESULTS

Median follow-up was 35 months (interquartile range: 22-52). Median biochemical disease-free survival (DFS) was 33 months (95% CI: 23-45). Median CE-free survival was 24 months (95% CI: 21-35). After multivariable analysis, DFS interval after primary radiotherapy, presalvage prostate-specific antigen (PSA), PSA-doubling time, prostatic volume, and T-stage (both MRI based) predicted BF. For the CE, PSA-doubling time was not predictive but additionally, primary Gleason score was. The adjusted C-statistics were 0.68 and 0.64 for BF and CE, respectively. Calibration was accurate until 48 months. The risk scores showed 3 groups, with biochemical DFS of 60%, 35%, and 7% and CE-free survival of 40%, 24%, and 0% at 4 years.

CONCLUSION

Our model, once externally validated, could allow for better selection of patients for focal salvage HIFU.

Clinically insignificant prostate cancer suitable for active surveillance according to Prostate Cancer Research International: Active surveillance criteria: Utility of PI-RADS v2

BACKGROUND

Active surveillance (AS) is an important treatment strategy for prostate cancer (PCa). Prostate Imaging-Reporting and Data System (PI-RADS) v2 has been addressed, but few studies have reported the value of PI-RADS v2 for assessing risk stratification in patients with PCa, especially on selecting potential candidates for AS.

PURPOSE

To investigate the utility of PI-RADS v2 and apparent diffusion coefficient (ADC) in evaluating patients with insignificant PCa, who are suitable for AS.

STUDY TYPE

Retrospective.

SUBJECTS

In all, 238 patients with PCa who met the Prostate Cancer Research International: Active Surveillance criteria underwent radical prostatectomy.

FIELD STRENGTH/SEQUENCE

3.0T, including T₂ -weighted, diffusion-weighted, and dynamic contrast-enhanced imaging.

ASSESSMENT

Insignificant cancer was defined histopathologically as an organ-confined disease with a tumor volume <0.5 cm³ without Gleason score 4-5. Patients were divided into two groups based on the PI-RADS v2 and tumor ADC: A, PI-RADS score ≤3 and ADC ≥1.095 × 10^-3 mm² /s; and B, PI-RADS score 4-5 or ADC <1.095 × 10^-3 mm² /s. Preoperative clinical and imaging variables were evaluated regarding the associations with insignificant cancer.

RESULTS

Of the 238 patients, 101 (42.8%) were diagnosed with insignificant cancer on pathological findings. The number of positive cores, prostate-specific antigen density (PSAD), PI-RADS v2 and tumor ADC were significantly associated with insignificant cancer on univariate analysis (P < 0.05). However, multivariate analysis indicated tumor ADC (odds ratio [OR] = 4.57, P < 0.001) and PI-RADS v2 (OR = 3.60, P < 0.001) were independent predictors of insignificant cancer. Area under the receiver operating characteristics curve (AUC) reached 0.803 when PI-RADS v2 (AUC = 0.747) was combined with tumor ADC (AUC = 0.786).

DATA CONCLUSION

The PI-RADS v2 together with tumor ADC may be a useful marker for predicting patients with insignificant PCa when considering AS.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1072-1079.

Application of Prostate Imaging Reporting and Data System Version 2 (PI-RADS v2): Interobserver Agreement and Positive Predictive Value for Localization of Intermediate- and High-Grade Prostate Cancers on Multiparametric Magnetic Resonance Imaging

RATIONALE AND OBJECTIVES

To evaluate interobserver agreement with the use of and the positive predictive value (PPV) of Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) for the localization of intermediate- and high-grade prostate cancers on multiparametric magnetic resonance imaging (mpMRI).

MATERIALS AND METHODS

In this retrospective, institutional review board-approved study, 131 consecutive patients who had mpMRI followed by transrectal ultrasound-MR imaging fusion-guided biopsy of the prostate were included. Two readers who were blinded to initial mpMRI reports, clinical data, and pathologic outcomes reviewed the MR images, identified all prostate lesions, and scored each lesion based on the PI-RADS v2. Interobserver agreement was assessed by intraclass correlation coefficient (ICC), and PPV was calculated for each PI-RADS category.

RESULTS

PI-RADS v2 was found to have a moderate level of interobserver agreement between two readers of varying experience, with ICC of 0.74, 0.72, and 0.67 for all lesions, peripheral zone lesions, and transitional zone lesions, respectively. Despite only moderate interobserver agreement, the calculated PPV in the detection of intermediate- and high-grade prostate cancers for each PI-RADS category was very similar between the two readers, with approximate PPV of 0%, 12%, 64%, and 87% for PI-RADS categories 2, 3, 4, and 5, respectively.

CONCLUSIONS

In our study, PI-RADS v2 has only moderate interobserver agreement, a similar finding in studies of the original PI-RADS and in initial studies of PI-RADS v2. Despite this, PI-RADS v2 appears to be a useful system to predict significant prostate cancer, with PI-RADS scores correlating well with the likelihood of intermediate- and high-grade cancers.

Impact of the integration of proton magnetic resonance imaging spectroscopy to PI-RADS 2 for prediction of high grade and high stage prostate cancer

Objective

To compare the predictions of dominant Gleason pattern ≥ 4 or non-organ confined disease with Prostate Imaging Reporting and Data System (PI-RADS v2) with or without proton magnetic resonance spectroscopic imaging (¹H-MRSI).

Materials and Methods

Thirty-nine men underwent 3-tesla endorectal multiparametric MRI including ¹H-MRSI and prostatectomy. Two radiologists assigned PI-RADS v2 and ¹H-MRSI scores to index lesions. Statistical analyses used logistic regressions, receiver operating characteristic (ROC) curves, and 2x2 tables for diagnostic accuracies.

Results

The sensitivity and specificity of ¹H-MRSI and PI-RADS v2 for high-grade prostate cancer (PCa) were 85.7% (57.1%) and 92.9% (100%), and 56% (68.0%) and 24.0% (24.0%). The sensitivity and specificity of ¹H-MRSI and PI-RADS v2 for extra-prostatic extension (EPE) were 64.0% (40%) and 20.0% (48%), and 50.0% (57.1%) and 71.4% (64.3%). The area under the ROC curves (AUC) for prediction of high-grade prostate cancer were 0.65 and 0.61 for PI-RADS v2 and 0.72 and 0.70 when combined with ¹H-MRSI (readers 1 and 2, p = 0.04 and 0.21). For prediction of EPE the AUC were 0.54 and 0.60 for PI-RADS v2 and 0.55 and 0.61 when combined with ¹H-MRSI (p > 0.05).

Conclusion

¹H-MRSI might improve the discrimination of high-grade prostate cancer when combined to PI-RADS v2, particularly for PI-RADS v2 score 4 lesions, but it does not affect the prediction of EPE.

Predictive role of Trimprob associated with multiparametric MRI in the diagnosis of prostate cancer

Objectives

To evaluate the predictive value of TRIMprob test to detect prostate cancer (PCa) in patients referred to prostate biopsy (PB).

Material and Methods

Patients with PSA <10ng/mL and rectal exam without findings suggestive of prostate cancer were selected for TRIMprob evaluation. Exam was performed by a single operator through transperineal approach. Patients admitted for the study were submitted to TRIMprob and multiparametric magnetic resonance (mpMRI) and posteriorly to PB.

Results

In total, 77 patients were included. TRIMprob showed evidences of PCa in 25 (32.5%) and was negative in 52 patients (67.5%). The rate of detection of prostate cancer at biopsy was higher in patients with positive TRIMprob (16/25; 64.0%) than in patients with negative TRIMprob (11/52; 21.1%; p<0.001). Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of TRIMprob were respectively 61.5%, 82.0%, 64.0%, 80.3% and 74.0%. ROC curve showed the following areas under the curve values for TRIMprob, mpMRI and combination of TRIMprob + mpMRI: 0.706; 0.662 and 0.741 respectively. At combined analysis, when both TRIMprob and mpMRI were negative for prostate cancer, accuracy was 96.3% or only 1 in 27 PB was positive (3.7%).

Conclusions

Trimprob had similar predictive value for PCa in patients submitted to PB as mpMRI. Combined TRIMprob and mpMRI showed higher accuracy than when performed singly.

Evidenced-based clinical practice guideline for prostate cancer (summary: Japanese Urological Association, 2016 edition)

These guidelines cover a wide range of topics from prostate cancer epidemiology to palliative care. Questions arising in daily clinical practice have been extracted and formulated as clinical questions. In the 4 years since the previous edition, there have been major changes - for example, robot-assisted prostatectomy has rapidly come into widespread use, and new hormones and anticancer drugs have been developed for castration-resistant prostate cancer. In response to these developments, the number of fields included in this guideline was increased from 11 in the 2012 edition to 16, and the number of clinical questions was increased from 63 to 70. The number of papers identified in searches of the existing literature increased from 4662 in the first edition, published in 2006, to 10 490 in the 2012 edition. The number of references has reached 29 448 just during this review period, indicating the exponential increase in research on the topic of prostate cancer. Clinical answers have been prepared based on the latest evidence. Recommendation grades for the clinical answers were determined by radiologists, pathologists, and other specialists in addition to urologists in order to reflect the recent advances and diversity of prostate cancer treatment. Here, we present a short English version of the original guideline, and overview its key clinical issues.

Interreader Agreement of Prostate Imaging Reporting and Data System Version 2 Using an In-Bore MRI-Guided Prostate Biopsy Cohort: A Single Institution's Initial Experience

OBJECTIVE

The purpose of this study is to determine the interobserver agreement of the Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) for diagnosing prostate cancer using in-bore MRI-guided prostate biopsy as the reference standard.

MATERIALS AND METHODS

Fifty-nine patients underwent in-bore MRI-guided prostate biopsy between January 21, 2010, and August 21, 2013, and underwent diagnostic multiparametric MRI 6 months or less before biopsy. A single index lesion per patient was selected after retrospective review of MR images. Three fellowship-trained abdominal radiologists (with 1-11 years' experience) blinded to clinical information interpreted all studies according to PI-RADSv2. Interobserver agreement was assessed using Cohen kappa statistics.

RESULTS

Thirty-eight lesions were in the peripheral zone and 21 were in the transition zone. Cancer was diagnosed in 26 patients (44%). Overall PI-RADS scores were higher for all biopsy-positive lesions (mean ± SD, 3.9 ± 1.1) than for biopsy-negative lesions (3.1 ± 1.0; p < 0.0001) and for clinically significant lesions (4.2 ± 1.0) than for clinically insignificant lesions (3.1 ± 1.0; p < 0.0001). Overall suspicion score interobserver agreement was moderate (κ = 0.45). There was moderate interobserver agreement among overall PI-RADS scores in the peripheral zone (κ = 0.46) and fair agreement in the transition zone (κ = 0.36).

CONCLUSION

PI-RADSv2 scores were higher in the biopsy-positive group. PI-RADSv2 showed moderate interobserver agreement among abdominal radiologists with no prior experience using the scoring system.

A meta-analysis of use of Prostate Imaging Reporting and Data System Version 2 (PI-RADS V2) with multiparametric MR imaging for the detection of prostate cancer

OBJECTIVES

This meta-analysis was undertaken to review the diagnostic accuracy of PI-RADS V2 for prostate cancer (PCa) detection with multiparametric MR (mp-MR).

METHODS

A comprehensive literature search of electronic databases was performed by two observers independently. Inclusion criteria were original research using the PI-RADS V2 system in reporting prostate MRI. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Data necessary to complete 2 × 2 contingency tables were obtained from the included studies.

RESULTS

Thirteen studies (2,049 patients) were analysed. This is an initial meta-analysis of PI-RADs V2 and the overall diagnostic accuracy in diagnosing PCa was as follows: pooled sensitivity, 0.85 (0.78-0.91); pooled specificity, 0.71 (0.60-0.80); pooled positive likelihood ratio (LR+), 2.92 (2.09-4.09); pooled negative likelihood ratio (LR-), 0.21 (0.14-0.31); pooled diagnostic odds ratio (DOR), 14.08 (7.93-25.01), respectively. Positive predictive values ranged from 0.54 to 0.97 and negative predictive values ranged from 0.26 to 0.92.

CONCLUSION

Currently available evidence indicates that PI-RADS V2 appears to have good diagnostic accuracy in patients with PCa lesions with high sensitivity and moderate specificity. However, no recommendation regarding the best threshold can be provided because of heterogeneity.

KEY POINTS

• PI-RADS V2 shows good diagnostic accuracy for PCa detection. • Initially pooled specificity of PI-RADS v2 remains moderate. • PCa detection is increased by experienced radiologists. • There is currently a high heterogeneity in prostate diagnostics with MRI.

Diagnostic value and relative weight of sequence-specific magnetic resonance features in characterizing clinically significant prostate cancers

Purpose

To assess the diagnostic weight of sequence-specific magnetic resonance features in characterizing clinically significant prostate cancers (csPCa).

Materials and methods

We used a prospective database of 262 patients who underwent T2-weighted, diffusion-weighted, and dynamic contrast-enhanced (DCE) imaging before prostatectomy. For each lesion, two independent readers (R1, R2) prospectively defined nine features: shape, volume (V_Max), signal abnormality on each pulse sequence, number of pulse sequences with a marked (S_Max) and non-visible (S_Min) abnormality, likelihood of extracapsular extension (ECE) and PSA density (dPSA). Overall likelihood of malignancy was assessed using a 5-level Likert score. Features were evaluated using the area under the receiver operating characteristic curve (AUC). csPCa was defined as Gleason ≥7 cancer (csPCa-A), Gleason ≥7(4+3) cancer (csPCa-B) or Gleason ≥7 cancer with histological extraprostatic extension (csPCa-C),

Results

For csPCa-A, the Signal1 model (S_Max+S_Min) provided the best combination of signal-related variables, for both readers. The performance was improved by adding V_Max, ECE and/or dPSA, but not shape. All models performed better with DCE findings than without.

When moving from csPCa-A to csPCa-B and csPCa-C definitions, the added value of V_Max, dPSA and ECE increased as compared to signal-related variables, and the added value of DCE decreased.

For R1, the best models were Signal1+ECE+dPSA (AUC = 0,805 [95%CI:0,757–0,866]), Signal1+V_Max+dPSA (AUC = 0.823 [95%CI:0.760–0.893]) and Signal1+ECE+dPSA [AUC = 0.840 (95%CI:0.774–0.907)] for csPCa-A, csPCA-B and csPCA-C respectively. The AUCs of the corresponding Likert scores were 0.844 [95%CI:0.806–0.877, p = 0.11], 0.841 [95%CI:0.799–0.876, p = 0.52]) and 0.849 [95%CI:0.811–0.884, p = 0.49], respectively.

For R2, the best models were Signal1+V_Max+dPSA (AUC = 0,790 [95%CI:0,731–0,857]), Signal1+V_Max (AUC = 0.813 [95%CI:0.746–0.882]) and Signal1+ECE+V_Max (AUC = 0.843 [95%CI: 0.781–0.907]) for csPCa-A, csPCA-B and csPCA-C respectively. The AUCs of the corresponding Likert scores were 0. 829 [95%CI:0.791–0.868, p = 0.13], 0.790 [95%CI:0.742–0.841, p = 0.12]) and 0.808 [95%CI:0.764–0.845, p = 0.006]), respectively.

Conclusion

Combination of simple variables can match the Likert score’s results. The optimal combination depends on the definition of csPCa.

Multi-parametric MRI imaging of the prostate-implications for focal therapy

The primary goal of a focal therapy treatment paradigm is to achieve cancer control through targeted tissue destruction while simultaneously limiting deleterious effects on peri-prostatic structures. Focal therapy approaches are employed in several oncologic treatment protocols, and have been shown to provide equivalent cancer control for malignancies such as breast cancer and renal cell carcinoma. Efforts to develop a focal therapy approach for prostate cancer have been challenged by several concepts including the multifocal nature of the disease and limited capability of prostate ultrasound and systematic biopsy to reliably localize the site(s) and aggressiveness of disease. Multi-parametric MRI (mpMRI) of the prostate has significantly improved disease localization, spatial demarcation and risk stratification of cancer detected within the prostate. The accuracy of this imaging modality has further enabled the urologist to improve biopsy approaches using targeted biopsy via MRI-ultrasound fusion. From this foundation, an improved delineation of the location of disease has become possible, providing a critical foundation to the development of a focal therapy strategy. This chapter reviews the accuracy of mpMRI for detection of “aggressive“ disease, the accuracy of mpMRI in determining the tumor volume, and the ability of mpMRI to accurately identify the index lesion. While mpMRI provides a critical, first step in developing a strategy for focal therapy, considerable questions remain regarding the relationship between MR identified tumor volume and pathologic tumor volume, the accuracy and utility of mpMRI for treatment surveillance and the optimal role and timing of follow-up mpMRI.

Is contrast enhancement needed for diagnostic prostate MRI?

Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) provides clinical guidelines for multiparametric magnetic resonance imaging (mpMRI) [T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)] of prostate. However, DCE-MRI seems to show a limited contribution in prostate cancer (PCa) detection and management. In our experience, DCE-MRI, did not show significant change in diagnostic performance in addition to DWI and T2WI [biparametric MRI (bpMRI)] which represent the predominant sequences to detect suspected lesions in peripheral and transitional zone (TZ). In this article we reviewed the role of DCE-MRI also indicating the potential contribute of bpMRI approach (T2WI and DWI) and lesion volume evaluation in the diagnosis and management of suspected PCa.