Prostate cancer: multiparametric MRI for index lesion localization--a multiple-reader study

Assessment of the accuracy of biparametric MRI/TRUS fusion-guided biopsy for index tumor evaluation using postoperative pathology specimens

BACKGROUND

Multiparametric MRI (mpMRI) is widely used for the diagnosis, surveillance, and staging of prostate cancer. However, it has several limitations, including higher costs, longer examination times, and the use of gadolinium-based contrast agents. This study aimed to investigate the accuracy of preoperatively assessed index tumors (ITs) using biparametric MRI (bpMRI)/transrectal ultrasound (TRUS) fusion biopsy compared with radical prostatectomy (RP) specimens.

METHODS

We included 113 patients diagnosed with prostate cancer through bpMRI/TRUS fusion-guided biopsies of lesions with a Prostate Imaging Reporting and Data System (PI-RADS) category ≥ 3. These patients underwent robot-assisted laparoscopic radical prostatectomy (RARP) at our institution between July 2017 and March 2023. We examined the localization of preoperative and postoperative ITs, the highest Gleason score (GS), and tumor diameter in these patients.

RESULTS

The preoperative cT stage matched the postoperative pT stage in 53 cases (47%), while 31 cases (27%) were upstaged, and 29 cases (26%) were downstaged (Weighted Kappa = 0.21). The preoperative and postoperative IT localizations were consistent in 97 cases (86%). The concordance rate between Gleason groups in targeted biopsies and RP specimens was 51%, with an upgrade in 25 cases (23%) and a downgrade in 27 cases (25%) (Weighted Kappa = 0.42). The maximum diameter of the IT and the maximum cancer core length on biopsy were correlated with the RP tumor's maximum diameter (p < 0.001 for both).

CONCLUSION

The diagnostic accuracy of bpMRI/TRUS fusion biopsy is comparable to mpMRI, suggesting that it can be a cost-effective and time-saving alternative.

Is imaging accurate enough to detect index lesion in prostate cancer? Analysis of the performance of MRI and other imaging modalities

Prostate imaging techniques have progressed across the years allowing for a better detection and characterization of prostate cancer (PCa) lesions. These advancements have led to the possibility to also improve and tailor the treatments on the most aggressive lesion, defined as Index Lesion (IL), to reduce morbidity. The IL is, indeed, considered as the entity which encompass the most aggressive features in prostate cancer disease. Multiparametric magnetic resonance imaging (mpMRI) has emerged as the suggested tool to detect the disease and plan treatments, including those under investigation such as focal therapy (FT). Our review aimed to query the literature on the ability of mpMRI in IL detection and to explore the future perspectives in PCa IL diagnosis. A review of the literature was performed from January 2010 to July 2023. All studies investigating the performance of mpMRI and other main imaging techniques able to detect the IL were assessed and evaluated. mpMRI performs well in the detection of IL with a sensitivity which reaches 71% to 94% among the different studies. However, mpMRI seems to have limited sensitivity in the detection of small tumours (<0.5 mL) and low-grade histology lesions. To overcome these limitations other diagnostic imaging techniques have been proposed. Multiparametric Ultrasound has shown results comparable to mpMRI while detecting 4.3% fewer clinically significant PCa (P=0.042). Positron emission tomography-based modalities using PSMA seems to have higher sensitivity than mpMRI, being able to yield from 13.5% to 18.2% additional cancers. MRI has emerged as the recommended tool since most of the IL can be easily identified, and is the imaging of choice while selecting patients for FT. Other imaging modalities has been proposed to improve PCa lesions detection, but results need to be confirmed by ongoing randomized controlled trial.

Microultrasound in the detection of the index lesion in prostate cancer

INTRODUCTION AND OBJECTIVE

The natural progression of prostate cancer is primarily driven by an index lesion (IL). Studies have shown that different metastases within the same patient arise from a single precursor cell. Therefore, our aim is to assess the effectiveness of transrectal microultrasound (MUS) in comparison to multiparametric magnetic resonance imaging (mpMRI) for detecting the IL in prostate cancer. We used quarter-mount pathological results as the reference standard for this evaluation.

MATERIALS AND METHODS

Three hundred and sixty-three patients who underwent Robot-Assisted Radical Prostatectomy (RARP) from June 2021 to August 2022 were included. All received mpMRI and MUS before RARP. MUS was performed by experienced operators blinded to mpMRI and biopsy results. The IL in the radical prostatectomy specimen was defined as the lesion with extraprostatic extension, the highest Grade Group (GG), or the largest tumor volume if the GG was the same. The correlation between imaging and final pathology findings was performed. A descriptive statistical analysis is presented.

RESULTS

The patients' prostates were analyzed in 12 regions (anterior/posterior, right/left, apex/mid/base). A total of 4308 regions were identified. Of these, 935 were involved by the ILs. Compared with final pathology, MUS demonstrated a sensitivity, specificity, PPV, and NPV of 68.7%, 96.3%, 80.8%, and 93.1%, respectively, while mpMRI showed a sensitivity, specificity, PPV, and NPV of 68.6%, 97.2%, 86.1%, and 92.5%, respectively, for the detection of the IL. Most of the lesions missed by MUS were located in the anterior zone (62%).

CONCLUSION

MUS exhibits a diagnostic performance similar to mpMRI when it comes to detecting the IL in prostate cancer. MUS is a cost-effective option, offers real-time evaluation, and has no delay in the acquisition process.

Deep Learning Reconstruction Enables Highly Accelerated Biparametric MR Imaging of the Prostate

BACKGROUND

Early diagnosis and treatment of prostate cancer (PCa) can be curative; however, prostate-specific antigen is a suboptimal screening test for clinically significant PCa. While prostate magnetic resonance imaging (MRI) has demonstrated value for the diagnosis of PCa, the acquisition time is too long for a first-line screening modality.

PURPOSE

To accelerate prostate MRI exams, utilizing a variational network (VN) for image reconstruction.

STUDY TYPE

Retrospective.

SUBJECTS

One hundred and thirteen subjects (train/val/test: 70/13/30) undergoing prostate MRI.

FIELD STRENGTH/SEQUENCE

3.0 T; a T2 turbo spin echo (TSE) T2-weighted image (T2WI) sequence in axial and coronal planes, and axial echo-planar diffusion-weighted imaging (DWI).

ASSESSMENT

Four abdominal radiologists evaluated the image quality of VN reconstructions of retrospectively under-sampled biparametric MRIs (bp-MRI), and standard bp-MRI reconstructions for 20 test subjects (studies). The studies included axial and coronal T2WI, DWI B50 seconds/mm² and B1000 seconds/mm (4-fold T2WI, 3-fold DWI), all of which were evaluated separately for image quality on a Likert scale (1: non-diagnostic to 5: excellent quality). In another 10 test subjects, three readers graded lesions on bp-MRI-which additionally included calculated B1500 seconds/mm² , and apparent diffusion coefficient map-according to the Prostate Imaging Reporting and Data System (PI-RADS v2.1), for both VN and standard reconstructions. Accuracy of PI-RADS ≥3 for clinically significant cancer was computed. Projected scan time of the retrospectively under-sampled biparametric exam was also computed.

STATISTICAL TESTS

One-sided Wilcoxon signed-rank test was used for comparison of image quality. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for lesion detection and grading. Generalized estimating equation with cluster effect was used to compare differences between standard and VN bp-MRI. A P-value of <0.05 was considered statistically significant.

RESULTS

Three of four readers rated no significant difference for overall quality between the standard and VN axial T2WI (Reader 1: 4.00 ± 0.56 (Standard), 3.90 ± 0.64 (VN) P = 0.33; Reader 2: 4.35 ± 0.74 (Standard), 3.80 ± 0.89 (VN) P = 0.003; Reader 3: 4.60 ± 0.50 (Standard), 4.55 ± 0.60 (VN) P = 0.39; Reader 4: 3.65 ± 0.99 (Standard), 3.60 ± 1.00 (VN) P = 0.38). All four readers rated no significant difference for overall quality between standard and VN DWI B1000 seconds/mm² (Reader 1: 2.25 ± 0.62 (Standard), 2.45 ± 0.75 (VN) P = 0.96; Reader 2: 3.60 ± 0.92 (Standard), 3.55 ± 0.82 (VN) P = 0.40; Reader 3: 3.85 ± 0.72 (Standard), 3.55 ± 0.89 (VN) P = 0.07; Reader 4: 4.70 ± 0.76 (Standard); 4.60 ± 0.73 (VN) P = 0.17) and three of four readers rated no significant difference for overall quality between standard and VN DWI B50 seconds/mm² (Reader 1: 3.20 ± 0.70 (Standard), 3.40 ± 0.75 (VN) P = 0.98; Reader 2: 2.85 ± 0.81 (Standard), 3.00 ± 0.79 (VN) P = 0.93; Reader 3: 4.45 ± 0.72 (Standard), 4.05 ± 0.69 (VN) P = 0.02; Reader 4: 4.50 ± 0.69 (Standard), 4.45 ± 0.76 (VN) P = 0.50). In the lesion evaluation study, there was no significant difference in the number of PI-RADS ≥3 lesions identified on standard vs. VN bp-MRI (P = 0.92, 0.59, 0.87) with similar sensitivity and specificity for clinically significant cancer. The average scan time of the standard clinical biparametric exam was 11.8 minutes, and this was projected to be 3.2 minutes for the accelerated exam.

DATA CONCLUSION

Diagnostic accelerated biparametric prostate MRI exams can be performed using deep learning methods in <4 minutes, potentially enabling rapid screening prostate MRI.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 5.

Simplified PI-RADS (S-PI-RADS) for biparametric MRI to detect and manage prostate cancer: What urologists need to know

Biparametric magnetic resonance imaging (bpMRI) of the prostate has emerged as an alternative to multiparametric MRI (mpMRI) for the detection of clinically significant prostate cancer (csPCa). However, while the Prostate Imaging Reporting and Data System (PI-RADS) is widely known for mpMRI, a proper PI-RADS for bpMRI has not yet been adopted. In this review, we report the current status and the future directions of bpMRI, and propose a simplified PI-RADS (S-PI-RADS) that could help radiologists and urologists in the detection and management of PCa.

Comparison of MRI, PSMA PET/CT, and Fusion PSMA PET/MRI for Detection of Clinically Significant Prostate Cancer

PURPOSE

The aim of our study is to compare the efficacy of positron emission tomography (PET) and magnetic resonance imaging (MRI) for detecting intraprostatic lesions in patients with clinically significant prostate cancer who underwent radical prostatectomy; additionally, investigate the benefits of rostate-specific membrane antigen (PSMA) PET-MR software fusion images to the diagnosis.

METHODS

Thirty patients, who underwent radical prostatectomy between June 2015 and April 2018, were included in the study. Subjects with gallium PSMA PET-CT and multiparametric prostate MRI performed according to Prostate Imaging Reporting and Data System v2 criteria in our clinic were included in the study. 68Ga-PSMA PET-CT images were fused with MR sequences for analysis.

RESULTS

The mean age of cases was 63.2 years (ranged from 45 to 79 years). Index lesions of 29 cases were detected by MRI and 22 of them by PET CT. Both modalities were found to be less sensitive for detection of bilaterality and multifocality (42.85% and 20% for MRI, 28.57% and 20% for PET CT, respectively). There was no statistically significant difference between modalities. It was observed that if a clinically significant tumor focus was not detected by MRI, it was small (6 mm or less) in diameter or had a low Gleason score.

CONCLUSIONS

Software fusion PSMA PET-MRI increased the sensitivity of the index lesion identification compared with PSMA PET-CT and also increased the sensitivity of real lesion size identification compared with multiparametric prostate MRI.

Effect of Echo Times on Prostate Cancer Detection on T2-Weighted Images

PURPOSE

To compare the effect of different echo times (TE) on the detection of prostate cancer (PCa) on T2-weighted MR images.

MATERIALS AND METHODS

This study recruited patients (n = 38) with histologically confirmed PCa who underwent preoperative 3T MRI. Three radiologists independently marked region on interests (ROIs) on suspected PCa lesions on T2-weighted images at different TEs: 90, 150, and 180 ms obtained with Turbo Spin Echo imaging protocol with multiple echoes. The ROIs were assigned a value 1-5 indicating the reviewer's confidence in accurately detecting PCa. These ROIs were compared to histologically confirmed PCa (n = 95) on whole mount prostatectomy sections to calculate sensitivity, positive predictive value (PPV), and confidence score.

RESULTS

Two radiologists (R1, R2) showed significantly increased sensitivity for PCa detection at 180 ms TE compared to 90 ms (R1: 43.2, 50.5, 50.5%, R2: 45.3, 44.2, 53.7% at TE of 90, 150, 180 ms, respectively) (p = 0.048, 0.033 for R1 and R2). Sensitivity was similar for radiologist 3 (45.3%-46.3%) at different TE values (p = 0.953). No significant difference in the PPV (R1: 64.1%-70.6%, R2: 46.7%-56.0%, R3: 70.5%-81.5%) and the confidence score assigned (R1: 4.6-4.8, R2: 4.6-4.8 R3: 4.3-4.4) was found for either of the radiologists.

CONCLUSION

Our results suggest improved detection of PCa with similar PPV and confidence scores when higher TE values are utilized for T2-weighted image acquisition.

Clinical utility of combined T2-weighted imaging and T2-mapping in the detection of prostate cancer: a multi-observer study

Background

To evaluate the clinical utility of combined T2-weighted imaging and T2-mapping for the detection of prostate cancer.

Methods

Forty patients underwent multiparametric magnetic resonance imaging (mpMRI) and T2-mapping of the prostate. Three readers each reviewed two sets of images: T2-weighted fast spin-echo (FSE) sequence (standard T2), and standard T2 in combination with T2-mapping. Each reader assigned probability scores for malignancy to each zone [peripheral zone (PZ) or transition zone (TZ)]. Inter-observer variability for standard T2 and combined standard T2 with T2-mapping were assessed. Diagnostic accuracy was compared between standard T2 and combined standard T2 with T2-mapping.

Results

There was fair agreement between all three readers for standard T2 [intraclass correlation coefficient (ICC) =0.56] and combined standard T2 with T2-mapping (ICC =0.58). There was no significant difference in the area under the receiver operator characteristics curve for standard T2 compared to combined standard T2 with T2-mapping (0.89 vs. 0.82, P=0.31). Sensitivity (Sn) for combined standard T2 with T2-mapping was significantly higher compared to standard T2 alone (73.0% vs. 49.2%, P=0.006). Specificity (Sp) for combined standard T2 with T2-mapping was borderline significantly lower compared to standard T2 alone (89.3% vs. 94.9%, P=0.05). There was no significant differences between the negative predictive values (NPVs) and positive predictive values (PPVs) (P=0.07, P=0.45).

Conclusions

Combination of T2-weighted imaging and T2-mapping could potentially increase Sn for prostate malignancy compared to T2-weighted imaging alone.

MRI in the Management of Prostate Cancer

Multiparametric MRI has a changing role in prostate cancer diagnosis. Internationally recognized consensus documents such as prostate imaging reporting and data system version have been developed and adapted to standardize the acquisition and reporting of prostate MRI. The improvement in scanning techniques and development of highly sensitive functional sequences have improved the detection of clinically significant prostate cancer as well as treatment planning and follow up. This has led to a recent NICE recommendation to use prostate MRI as the initial investigation in men with clinically suspected localized disease. The results of several recent international MRI prostate trials are influencing the way imaging is used to stratify which patients require a prostate biopsy as well as how MRI guidance is used to target biopsies.

Influence of the Location and Zone of Tumor in Prostate Cancer Detection and Localization on 3-T Multiparametric MRI Based on PI-RADS Version 2

OBJECTIVE. The objective of our study was to determine the performance of 3-T multiparametric MRI (mpMRI) for prostate cancer (PCa) detection and localization, stratified by anatomic zone and level, using Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) and whole-mount histopathology (WMHP) as reference. MATERIALS AND METHODS. Multiparametric MRI examinations of 415 consecutive men were compared with thin-section WMHP results. A genitourinary radiologist and pathologist collectively determined concordance. Two radiologists assigned PI-RADSv2 scores and sector location to all detected foci by consensus. Tumor detection rates were calculated for clinical and pathologic (tumor location and zone) variables. Both rigid and adjusted sector-matching models were used to account for fixation-related issues. RESULTS. Of 863 PCa foci in 16,185 prostate sectors, the detection of overall and index PCa lesions in the midgland, base, and apex was 54.9% and 83.1%, 42.1% and 64.0% (p = 0.04, p = 0.02), and 41.9% and 71.4% (p = 0.001, p = 0.006), respectively. Tumor localization sensitivity was highest in the midgland compared with the base and apex using an adjusted match compared with a rigid match (index lesions, 71.3% vs 43.7%; all lesions, 70.8% vs 36.0%) and was greater in the peripheral zone (PZ) than in the transition zone. Three-Tesla mpMRI had similarly high specificity (range, 93.8-98.3%) for overall and index tumor localization when using both rigid and adjusted sector-matching approaches. CONCLUSION. For 3-T mpMRI, the highest sensitivity (83.1%) for detection of index PCa lesions was in the midgland, with 98.3% specificity. Multiparametric MRI performance for sectoral localization of PCa within the prostate was moderate and was best for index lesions in the PZ using an adjusted model.

"In-Bore" MRI-Guided Prostate Biopsy for Prostate Cancer Diagnosis: Results from 140 Consecutive Patients

Objectives

Transrectal ultrasound-guided biopsy (TRUS-GB) is the current reference standard procedure for diagnosis of prostate cancer (PCa) but this procedure has limitations related to the low detection rate (DR) described in the literature. The aim of the study was to evaluate the DR efficiency, and complication rate in a pure "in-bore" magnetic resonance imaging-guided biopsy (MRI-GB) series according to the Prostate Imaging Reporting and Data System, version 2 (PI-RADS v2).

Materials and Methods

From July 2015 to April 2018, a series of 142 consecutive patients undergoing MRI-GB were prospectively enrolled. According to the European Society of Urogenital Radiology guidelines, the presence of clinically significant PCa (csPCa) on multiparametric magnetic resonance imaging was defined as equivocal, likely, or highly likely according to a PI-RADS v2, score of 3, 4, or 5, respectively.

Results

Of 142 patients, 76 (53.5%) were biopsy naive and 66 (46.5%) had ≤ 1 previous negative set of random TRUS-GB findings. The MRI-GB findings were positive in 75 of 142 patients with a DR of 52.8%. Of the 76 patients with ≤ 1 previous set of TRUS-GB, 43 had PCa found by MRI-GB, with a DR of 57.3%. The DR in the 66 biopsy-naive patients was 48% (32/66). Of the 75 patients with positive biopsy findings, 54 (80.5%) were found to have csPCa on histological examination. Of these 54 patients, 28 had an International Society of Urological Pathology grade 2; 5 had grade 3, 19 had grade 4, and 2 had grade 5. Considering the anatomic distribution of the index lesions using the PI-RADS v2 scheme, the probability of PCa was greater for lesions located in the peripheral zone (55 of 75, 73.3%) than for those in the central zone (20 of 75, 26.7%).

Conclusions

Our study conducted on 142 patients confirmed the greater DR of csPCa by MRI-GB, with a very low number of cores needed and a negligible incidence of complications, especially in patients with a previous negative biopsy. MRI-GB is optimal for the diagnosis of anterior and central lesions.

The performance of intravoxel-incoherent motion diffusion-weighted imaging derived hypoxia for the risk stratification of prostate cancer in peripheral zone

PURPOSE

To assess the association between intravoxel-incoherent motion diffusion-weighted imaging (IVIM) derived hypoxia and the aggressiveness of prostate cancer (PCa) and to explore its contribution to the risk stratification of PCa.

METHODS

Seventy-five peripheral zone (PZ) PCa patients, who underwent multiparametric MRI (mpMRI), were included in this study. Systematic ultrasound guided biopsy was used as reference. IVIM was acquired with 5 b values (b = 0∼750 s/mm²). Apparent diffusion coefficient (ADC), pure tissue diffusion (Ds), volume fraction of pseudo-diffusion (fp), hypoxic fraction (HF_DWI), hypoxia score (HS_DWI) and relative oxygen saturation(rOS_DWI), were calculated and histogram analysis was applied. Groups comparison was performed between low-intermediate-grade group (LG, the International Society of Urological Pathology (ISUP) Gleason Grade (GG) ≤2) and high-grade (HG, ISUP GG ≥ 3) group. The correlation between diffusion parameters and ISUP GG was assessed. Cross-validated Support Vector Machine (SVM) Classification was performed and compared with univariate ROC analysis to explore the risk stratification of PZ PCa.

RESULTS

Mean, median, and the 10th percentile of Ds differed significantly between groups (p < 0.05). Several parameters significantly correlated with ISUP grade, and the 10th percentile of Ds showed the strongest correlation (ρ= - 0.284). The prediction model containing IVIM derived hypoxia yielded an area under the receiver operating characteristics curve (AUC) ranging 0.749-0.786 for cross-validation. The AUCs of the SVM modeling were higher than that of any single parameter.

CONCLUSION

IVIM derived hypoxia demonstrated significant correlation with the aggressiveness of PCa. It's supplemental to the MRI assessment of PCa with a promising stratification of risk stratification of PZ PCa.

The Effect of Image Resolution on Deep Learning in Radiography

PURPOSE

To examine variations of convolutional neural network (CNN) performance for multiple chest radiograph diagnoses and image resolutions.

MATERIALS AND METHODS

This retrospective study examined CNN performance using the publicly available National Institutes of Health chest radiograph dataset comprising 112 120 chest radiographic images from 30 805 patients. The network architectures examined included ResNet34 and DenseNet121. Image resolutions ranging from 32 × 32 to 600 × 600 pixels were investigated. Network training paradigms used 80% of samples for training and 20% for validation. CNN performance was evaluated based on area under the receiver operating characteristic curve (AUC) and label accuracy. Binary output networks were trained separately for each label or diagnosis under consideration.

RESULTS

Maximum AUCs were achieved at image resolutions between 256 × 256 and 448 × 448 pixels for binary decision networks targeting emphysema, cardiomegaly, hernias, edema, effusions, atelectasis, masses, and nodules. When comparing performance between networks that utilize lower resolution (64 × 64 pixels) versus higher (320 × 320 pixels) resolution inputs, emphysema, cardiomegaly, hernia, and pulmonary nodule detection had the highest fractional improvements in AUC at higher image resolutions. Specifically, pulmonary nodule detection had an AUC performance ratio of 80.7% ± 1.5 (standard deviation) (0.689 of 0.854) whereas thoracic mass detection had an AUC ratio of 86.7% ± 1.2 (0.767 of 0.886) for these image resolutions.

CONCLUSION

Increasing image resolution for CNN training often has a trade-off with the maximum possible batch size, yet optimal selection of image resolution has the potential for further increasing neural network performance for various radiology-based machine learning tasks. Furthermore, identifying diagnosis-specific tasks that require relatively higher image resolution can potentially provide insight into the relative difficulty of identifying different radiology findings. Supplemental material is available for this article. © RSNA, 2020See also the commentary by Lakhani in this issue.

Detection and Localization of Prostate Cancer at 3-T Multiparametric MRI Using PI-RADS Segmentation

OBJECTIVE. The purpose of this study is to determine the overall and sector-based performance of 3-T multiparametric MRI for prostate cancer (PCa) detection and localization by using Prostate Imaging-Reporting and Data System version 2 (PI-RADSv2) scoring and segmentation compared with whole-mount histopathologic analysis. MATERIALS AND METHODS. Multiparametric 3-T MRI examinations of 415 consecutive men were compared with thin-section whole-mount histopathologic analysis. A genitourinary radiologist and pathologist collectively determined concordance. Two radiologists assigned PI-RADSv2 categories and sectoral location to all detected foci by consensus. Tumor detection rates were calculated for clinical and pathologic (Gleason score) variables. Both rigid and adjusted sector-matching models were used to account for fixation-related issues. RESULTS. The 415 patients had 863 PCa foci (52.7% had a Gleason score ≥ 7, 61.9% were ≥ 1 cm, and 90.4% (375/415) of index lesions were ≥ 1 cm) and 16,185 prostate sectors. Multiparametric MRI enabled greater detection of PCa lesions 1 cm or larger (all lesions vs index lesions, 61.6% vs 81.6%), lesions with Gleason score greater than or equal to 7 (all lesions vs index lesions, 71.4% vs 80.9%), and index lesions with both Gleason score greater than or equal to 7 and size 1 cm or larger (83.3%). Higher sensitivity was obtained for adjusted versus rigid tumor localization for all lesions (56.0% vs 28.5%), index lesions (55.4% vs 34.3%), lesions with Gleason score greater than or equal to 7 (55.7% vs 36.0%), and index lesions 1 cm or larger (56.1% vs 35.0%). Multiparametric 3-T MRI had similarly high specificity (96.0-97.9%) for overall and index tumor localization with adjusted and rigid sector-matching approaches. CONCLUSION. Using 3-T multiparametric MRI and PI-RADSv2, we achieved the highest sensitivity (83.3%) for the detection of lesions 1 cm or larger with Gleason score greater than or equal to 7. Sectoral localization of PCa within the prostate was moderate and was better with an adjusted model than with a rigid model.

Hemiablation of Localized Prostate Cancer by High-Intensity Focused Ultrasound: A Series of 35 Cases

Prostate cancer (PrC) is one of the most common tumors diagnosed in men. The detection rate of localized PrC has been dramatically enhanced by screening and the development of visualization methods. There are currently several techniques for focal treatment available, among which the most interesting in our opinion is high-intensity focused ultrasound (HIFU). Currently, HIFU hemiablation of PrC is not an established treatment, although evidence of its effectiveness and safety is growing. We have been performing HIFU hemiablation since 2013 and here report our results to add to the evidence on the effectiveness of the technique. Between October 2013 and December 2016, we performed HIFU hemiablation of the prostate for a total of 35 patients with confirmed PrC stage <cT2a at our urology clinic and retrospectively examined duration of ablation, pre- and postoperative prostate-specific antigen (PSA) levels, prostate volume, erectile function, and dysuria. The mean duration of ablation was 22 min (10-35). The mean postoperative hospital stay was 4 days. None of the patients experienced serious complications. Postoperative PSA tests showed the greatest decrease after 3 months to 2.4 ng/mL on average (p < 0.001). The pathological focus seen on MRI before the procedure in each case was absent after 3 months. Control biopsy after 12 months revealed residual cancer in the contralateral lobe in 4 patients. The findings obtained during follow-up and from control biopsies indicate that the treatment was highly efficacious with a low rate of nonserious postoperative complications. HIFU hemiablation proved to be a reliable therapeutic modality for localized PrC and was associated with a low rate of complications and comparable risk of recurrence. Despite the fact that this method of treatment is currently experimental, the results of this case series and other studies indicate its feasibility and safety.

Diagnostic Accuracy of a MR Protocol Acquired with and without Endorectal Coil for Detection of Prostate Cancer: A Multicenter Study

Introduction

The purpose of this study was to compare diagnostic accuracy of a prostate multiparametric magnetic resonance imaging (mpMRI) protocol for detection of prostate cancer between images acquired with and without en-dorectal coil (ERC).

Materials

This study was approved by the regional ethics committee. Between 2014 and 2015, 33 patients (median age 51.3 years; range 42.1-77.3 years) who underwent prostate-MRI at 3T scanners at 2 different institutions, acquired with (mpMRI_ERC) and without (mpMRI_PPA) ERC and who received radical prostatectomy, were included in this retrospective study. Two expert readers (R1, R2) attributed a PI-RADS version 2 score for the most suspect (i. e. index) lesion for mpMRI_PPA and mpMRI_ERC. Sensitivity and positive predictive value for detection of index lesions were assessed using 2 × 2 contingency tables. Differences between groups were tested using the McNemar test. Whole-mount histopathology served as reference standard.

Results

On a quadrant-basis cumulative sensitivity ranged between 0.61-0.67 and 0.76-0.88 for mpMRI_PPA and mpMRI_ERC protocols, respectively (p > 0.05). Cumulative positive predictive value ranged between 0.80-0.81 and 0.89-0.91 for mpMRI_PPA and mpMRI_ERC protocols, respectively. The differences were not statistically significant for R1 (p = 0.267) or R2 (p = 0.508).

Conclusion

Our results suggest that there may be no significant differences for detection of prostate cancer between images acquired with and without an ERC.

Prostate Magnetic Resonance Imaging: Lesion Detection and Local Staging

Dramatic changes in the use of prostate magnetic resonance imaging (MRI) have occurred in the last decade. The recognition that MRI detects and localizes cancers with reasonable accuracy led to the development of directed biopsies. These image-guided biopsies have a higher sensitivity for clinically significant cancers and a lower sensitivity for indolent disease. Prospective trials provide level 1 evidence supporting the use of prostate MRI. For local staging, while the specificity of prostate MRI is high, its sensitivity is lacking for microscopic extraprostatic extension. Computer-aided diagnosis of prostate MRI promises to bring the diagnostic power of MRI to nonexpert readers and thus further integrate MRI into the diagnostic workup.

Performance of T2 Maps in the Detection of Prostate Cancer

RATIONALE AND OBJECTIVES

This study compares the performance of T2 maps in the detection of prostate cancer (PCa) in comparison to T2-weighted (T2W) magnetic resonance images.

MATERIALS AND METHODS

The prospective study was institutional review board approved. Consenting patients (n = 45) with histologic confirmed PCa underwent preoperative 3-T magnetic resonance imaging with or without endorectal coil. Two radiologists, working independently, marked regions of interests (ROIs) on PCa lesions separately on T2W images and T2 maps. Each ROI was assigned a score of 1-5 based on the confidence in accurately detecting cancer, with 5 being the highest confidence. Subsequently, the histologically confirmed PCa lesions (n = 112) on whole-mount sections were matched with ROIs to calculate sensitivity, positive predictive value (PPV), and radiologist confidence score. Quantitative T2 values of PCa and benign tissue ROIs were measured.

RESULTS

Sensitivity and confidence score for PCa detection were similar for T2W images (51%, 4.5 ± 0.8) and T2 maps (52%, 4.5 ± 0.6). However, PPV was significantly higher (P = .001) for T2 maps (88%) compared to T2W (72%) images. The use of endorectal coils nominally improved sensitivity (T2W: 55 vs 47%, T2 map: 54% vs 48%) compared to the use of no endorectal coils, but not the PPV and the confidence score. Quantitative T2 values for PCa (105 ± 28 milliseconds) were significantly (P = 9.3 × 10^-14) lower than benign peripheral zone tissue (211 ± 71 milliseconds), with moderate significant correlation with Gleason score (ρ = -0.284).

CONCLUSIONS

Our study shows that review of T2 maps by radiologists has similar sensitivity but higher PPV compared to T2W images. Additional quantitative information obtained from T2 maps is helpful in differentiating cancer from normal prostate tissue and determining its aggressiveness.

Computer-aided diagnosis prior to conventional interpretation of prostate mpMRI: an international multi-reader study

OBJECTIVES

To evaluate if computer-aided diagnosis (CAD) prior to prostate multi-parametric MRI (mpMRI) can improve sensitivity and agreement between radiologists.

METHODS

Nine radiologists (three each high, intermediate, low experience) from eight institutions participated. A total of 163 patients with 3-T mpMRI from 4/2012 to 6/2015 were included: 110 cancer patients with prostatectomy after mpMRI, 53 patients with no lesions on mpMRI and negative TRUS-guided biopsy. Readers were blinded to all outcomes and detected lesions per PI-RADSv2 on mpMRI. After 5 weeks, readers re-evaluated patients using CAD to detect lesions. Prostatectomy specimens registered to MRI were ground truth with index lesions defined on pathology. Sensitivity, specificity and agreement were calculated per patient, lesion level and zone-peripheral (PZ) and transition (TZ).

RESULTS

Index lesion sensitivity was 78.2% for mpMRI alone and 86.3% for CAD-assisted mpMRI (p = 0.013). Sensitivity was comparable for TZ lesions (78.7% vs 78.1%; p = 0.929); CAD improved PZ lesion sensitivity (84% vs 94%; p = 0.003). Improved sensitivity came from lesions scored PI-RADS < 3 as index lesion sensitivity was comparable at PI-RADS ≥ 3 (77.6% vs 78.1%; p = 0.859). Per patient specificity was 57.1% for CAD and 70.4% for mpMRI (p = 0.003). CAD improved agreement between all readers (56.9% vs 71.8%; p < 0.001).

CONCLUSIONS

CAD-assisted mpMRI improved sensitivity and agreement, but decreased specificity, between radiologists of varying experience.

KEY POINTS

• Computer-aided diagnosis (CAD) assists clinicians in detecting prostate cancer on MRI. • CAD assistance improves agreement between radiologists in detecting prostate cancer lesions. • However, this CAD system induces more false positives, particularly for less-experienced clinicians and in the transition zone. • CAD assists radiologists in detecting cancer missed on MRI, suggesting a path for improved diagnostic confidence.

Accuracy in local staging of prostate cancer by adding a three-dimensional T2-weighted sequence with radial reconstructions in magnetic resonance imaging

Background

The evidence supporting the use of magnetic resonance imaging (MRI) in prostate cancer detection has been established, but its accuracy in local staging is questioned.

Purpose

To investigate the additional value of multi-planar radial reconstructions of a three-dimensional (3D) T2-weighted (T2W) MRI sequence, intercepting the prostate capsule perpendicularly, for improving local staging of prostate cancer.

Material and Methods

Preoperative, bi-parametric prostate MRI examinations in 94 patients operated between June 2014 and January 2015 where retrospectively reviewed by two experienced abdominal radiologists. Each patient was presented in two separate sets including diffusion-weighted imaging, without and with the 3D T2W set that included radial reconstructions. Each set was read at least two months apart. Extraprostatic tumor extension (EPE) was assessed according to a 5-point grading scale. Sensitivity and specificity for EPE was calculated and presented as receiver operating characteristics (ROC) with area under the curve (AUC), using histology from whole-mount prostate specimen as gold standard. Inter-rater agreement was calculated for the two different reading modes using Cohen's kappa.

Results

The AUC for detection of EPE for Readers 1 and 2 in the two-dimensional (2D) set was 0.70 and 0.68, respectively, and for the 2D + 3D set 0.62 and 0.65, respectively. Inter-rater agreement (Reader 1 vs. Reader 2) on EPE using Cohen's kappa for the 2D and 2D + 3D set, respectively, was 0.42 and 0.17 (i.e. moderate and poor agreement, respectively).

Conclusion

The addition of 3D T2W MRI with radial reconstructions did not improve local staging in prostate cancer.

Focal Ablation of Prostate Cancer

The challenge to the urology community is to reduce the risks of screening and treatment by reducing the number of men undergoing unnecessary biopsy and whole-gland curative treatment of low-risk disease. There is compelling evidence that focal ablation of prostate cancer is truly minimally invasive and offers major functional advantages over whole-gland treatment.

What Are We Missing? False-Negative Cancers at Multiparametric MR Imaging of the Prostate

Purpose To characterize clinically important prostate cancers missed at multiparametric (MP) magnetic resonance (MR) imaging. Materials and Methods The local institutional review board approved this HIPAA-compliant retrospective single-center study, which included 100 consecutive patients who had undergone MP MR imaging and subsequent radical prostatectomy. A genitourinary pathologist blinded to MP MR findings outlined prostate cancers on whole-mount pathology slices. Two readers correlated mapped lesions with reports of prospectively read MP MR images. Readers were blinded to histopathology results during prospective reading. At histopathologic examination, 80 clinically unimportant lesions (<5 mm; Gleason score, 3+3) were excluded. The same two readers, who were not blinded to histopathologic findings, retrospectively reviewed cancers missed at MP MR imaging and assigned a Prostate Imaging Reporting and Data System (PI-RADS) version 2 score to better understand false-negative lesion characteristics. Descriptive statistics were used to define patient characteristics, including age, prostate-specific antigen (PSA) level, PSA density, race, digital rectal examination results, and biopsy results before MR imaging. Student t test was used to determine any demographic differences between patients with false-negative MP MR imaging findings and those with correct prospective identification of all lesions. Results Of the 162 lesions, 136 (84%) were correctly identified with MP MR imaging. Size of eight lesions was underestimated. Among the 26 (16%) lesions missed at MP MR imaging, Gleason score was 3+4 in 17 (65%), 4+3 in one (4%), 4+4 in seven (27%), and 4+5 in one (4%). Retrospective PI-RADS version 2 scores were assigned (PI-RADS 1, n = 8; PI-RADS 2, n = 7; PI-RADS 3, n = 6; and PI-RADS 4, n = 5). On a per-patient basis, MP MR imaging depicted clinically important prostate cancer in 99 of 100 patients. At least one clinically important tumor was missed in 26 (26%) patients, and lesion size was underestimated in eight (8%). Conclusion Clinically important lesions can be missed or their size can be underestimated at MP MR imaging. Of missed lesions, 58% were not seen or were characterized as benign findings at second-look analysis. Recognition of the limitations of MP MR imaging is important, and new approaches to reduce this false-negative rate are needed. ^© RSNA, 2017 Online supplemental material is available for this article.

Multiparametric magnetic resonance imaging identifies significant apical prostate cancers

OBJECTIVE

To determine if multiparametric (mp) magnetic resonance imaging (MRI) can identify significant apical disease, thereby informing decisions regarding preservation of the membranous urethra.

MATERIALS AND METHODS

Men undergoing radical prostatectomy (RP) between January 2012 and June 2016, who underwent a 12-core transrectal ultrasonography-guided systematic biopsy (SB), preoperative 3-Tesla MRI, and sectioning of the prostate specimen with tumour foci mapping, were extracted from a single surgeon's prospective longitudinal outcomes database. Apical SB and mpMRI lesion results were compared with regard to their ability to predict aggressive tumours in the prostatic apex (PA), defined as prostate cancer grade group >1.

RESULTS

Of the 100 men who met the eligibility criteria, 43 (43%) exhibited aggressive prostate cancer in the distal 5 mm of the apex. A Likert score >2 in the apical one-third of the prostate was found to be more reliable than any cancer found on apical SB at detecting aggressive cancer in the apex. On multivariate regression analysis, which included Likert score in the apex, age, prostate-specific antigen (PSA) level, prostate size and presence of any cancer on apical biopsy, only Likert score (P = 0.005) and PSA level (P = 0.025) were significant and independent predictors of aggressive cancer in the distal apex.

CONCLUSION

The results of the study showed that MRI was superior to SB at identifying aggressive prostate cancer within the distal PA and may be useful for planning the extent of apical preservation during RP.

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.

The role of MRI in prostate cancer diagnosis and management

Multiparametric MRI of the prostate demonstrates strong potential to address many limitations of traditional prostate cancer diagnosis and management strategies. Recent evidence supports roles for prostate MRI in prebiopsy risk stratification, guidance of targeted biopsy and preoperative disease staging. Prostate MRI may also assist the planning and follow-up of investigational partial gland ablative therapies. This article reviews the impact of prostate MRI on such diagnostic and therapeutic paradigms in contemporary prostate cancer management.

Utilization of multiparametric prostate magnetic resonance imaging in clinical practice and focal therapy: report from a Delphi consensus project

Purpose

To codify the use of multiparametric magnetic resonance imaging (mpMRI) for the interrogation of prostate neoplasia (PCa) in clinical practice and focal therapy (FT).

Methods

An international collaborative consensus project was undertaken using the Delphi method among experts in the field of PCa. An online questionnaire was presented in three consecutive rounds and modified each round based on the comments provided by the experts. Subsequently, a face-to-face meeting was held to discuss and finalize the consensus results.

Results

mpMRI should be performed in patients with prior negative biopsies if clinical suspicion remains, but not instead of the PSA test, nor as a stand-alone diagnostic tool or mpMRI-targeted biopsies only. It is not recommended to use a 1.5 Tesla MRI scanner without an endorectal or pelvic phased-array coil. mpMRI should be performed following standard biopsy-based PCa diagnosis in both the planning and follow-up of FT. If a lesion is seen, MRI-TRUS fusion biopsies should be performed for FT planning. Systematic biopsies are still required for FT planning in biopsy-naïve patients and for patients with residual PCa after FT. Standard repeat biopsies should be taken during the follow-up of FT. The final decision to perform FT should be based on histopathology. However, these consensus statements may differ for expert centers versus non-expert centers.

Conclusions

The mpMRI is an important tool for characterizing and targeting PCa in clinical practice and FT. Standardization of acquisition and reading should be the main priority to guarantee consistent mpMRI quality throughout the urological community.

Electronic supplementary material

The online version of this article (doi:10.1007/s00345-016-1932-1) contains supplementary material, which is available to authorized users.

The current and future role of magnetic resonance imaging in prostate cancer detection and management

Purpose

Accurate detection of clinically significant prostate cancer (PC) and correct risk attribution are essential to individually counsel men with PC. Multiparametric MRI (mpMRI) facilitates correct localization of index lesions within the prostate and MRI-targeted prostate biopsy (TPB) helps to avoid the shortcomings of conventional biopsy such as false-negative results or underdiagnosis of aggressive PC. In this review we summarize the different sequences of mpMRI, characterize the possibilities of incorporating MRI in the biopsy workflow and outline the performance of targeted and systematic cores in significant cancer detection. Furthermore, we outline the potential of MRI in patients undergoing active surveillance (AS) and in the pre-operative setting.

Materials and methods

An electronic MEDLINE/PubMed search up to February 2015 was performed. English language articles were reviewed for inclusion ability and data were extracted, analyzed and summarized.

Results

Targeted biopsies significantly outperform conventional systematic biopsies in the detection of significant PC and are not inferior when compared to transperineal saturation biopsies. MpMRI can detect index lesions in app. 90% of cases as compared to prostatectomy specimen. The diagnostic performance of biparametric MRI (T2w + DWI) is not inferior to mpMRI, offering options to diminish cost- and time-consumption. Since app 10% of significant lesions are still MRI-invisible, systematic cores seem to be necessary. In-bore biopsy and MRI/TRUS-fusion-guided biopsy tend to be superior techniques compared to cognitive fusion. In AS, mpMRI avoids underdetection of significant PC and confirms low-risk disease accurately. In higher-risk disease, pre-surgical MRI can change the clinically-based surgical plan in up to a third of cases.

Conclusions

mpMRI and targeted biopsies are able to detect significant PC accurately and mitigate insignificant PC detection. As long as the negative predictive value (NPV) is still imperfect, systematic cores should not be omitted for optimal staging of disease. The potential to correctly classify aggressiveness of disease in AS patients and to guide and plan prostatectomy is evolving.

Detection of prostate cancer with multiparametric MRI (mpMRI): effect of dedicated reader education on accuracy and confidence of index and anterior cancer diagnosis

PURPOSE

To evaluate the impact of dedicated reader education on accuracy/confidence of peripheral zone index cancer and anterior prostate cancer (PCa) diagnosis with mpMRI; secondary aim was to assess the ability of readers to differentiate low-grade cancer (Gleason 6 or below) from high-grade cancer (Gleason 7+).

MATERIALS AND METHODS

Five blinded radiology fellows evaluated 31 total prostate mpMRIs in this IRB-approved, HIPAA-compliant, retrospective study for index lesion detection, confidence in lesion diagnosis (1-5 scale), and Gleason grade (Gleason 6 or lower vs. Gleason 7+). Following a dedicated education program, readers reinterpreted cases after a memory extinction period, blinded to initial reads. Reference standard was established combining whole mount histopathology with mpMRI findings by a board-certified radiologist with 5 years of prostate mpMRI experience.

RESULTS

Index cancer detection: pre-education accuracy 74.2%; post-education accuracy 87.7% (p = 0.003). Confidence in index lesion diagnosis: pre-education 4.22 ± 1.04; post-education 3.75 ± 1.41 (p = 0.0004). Anterior PCa detection: pre-education accuracy 54.3%; post-education accuracy 94.3% (p = 0.001). Confidence in anterior PCa diagnosis: pre-education 3.22 ± 1.54; post-education 4.29 ± 0.83 (p = 0.0003). Gleason score accuracy: pre-education 54.8%; post-education 73.5% (p = 0.0005).

CONCLUSIONS

A dedicated reader education program on PCa detection with mpMRI was associated with a statistically significant increase in diagnostic accuracy of index cancer and anterior cancer detection as well as Gleason grade identification as compared to pre-education values. This was also associated with a significant increase in reader diagnostic confidence. This suggests that substantial interobserver variability in mpMRI interpretation can potentially be reduced with a focus on education and that this can occur over a fellowship training year.

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.

Characteristics of Detected and Missed Prostate Cancer Foci on 3-T Multiparametric MRI Using an Endorectal Coil Correlated With Whole-Mount Thin-Section Histopathology

OBJECTIVE

The objective of this study was to determine the characteristics of prostate cancer foci missed on 3-T multiparametric MRI performed with an endorectal coil.

MATERIALS AND METHODS

The MRI examinations of 122 patients who underwent 3-T multiparametric MRI of the prostate with an endorectal coil were compared with whole-mount histopathology obtained after radical prostatectomy. The mean age of the patients was 60.6 years (SD, 7.6 years), and the mean prostate-specific antigen value was 7.2 ng/mL (SD, 5.9 ng/mL). The clinical, multiparametric MRI (i.e., T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast-enhanced imaging), and histopathologic features were obtained. After an independent review, two blinded genitourinary radiologists matched each case with a genitourinary pathologist. A structured reporting system was used to classify the multiparametric MRI features of each MRI-detected lesion. A chi-square analysis was performed for categoric variables, and the t test was performed for continuous variables.

RESULTS

On whole-mount histopathology, 285 prostate cancer foci were detected in 122 patients. Of the 285 cancer foci detected at histopathology, 153 (53.3%) were missed on MRI and 132 (46.7%) were detected on MRI. Of the missed lesions, 75.2% were low-grade prostate cancer. Multiparametric MRI had a significantly higher sensitivity for prostate cancer foci 1 cm or larger than for subcentimeter foci (81.1% vs 18.9%, respectively; p < 0.001), for lesions with a Gleason score of 7 or greater than for lesions with a Gleason score of 6 (72.7% vs 27.3%; p < 0.01), and for index lesions than for satellite lesions (80.3% vs 20.8%; p < 0.01). The 3-T multiparametric MRI examinations showed a higher detection rate for lesions in the midgland or base of the gland compared with lesions in the apex (52.3% vs 22.0%, respectively; p < 0.01).

CONCLUSION

Compared with the prostate cancer lesions that were detected on multiparametric MRI, the prostate cancer lesions that were missed were significantly smaller, were more likely to be low-grade lesions (i.e., Gleason score of 6), were more commonly satellite lesions, and were more likely to be located in the prostatic apex.

Multiparametric magnetic resonance imaging for prostate cancer: A review and update for urologists

Recently, imaging of prostate cancer has greatly advanced since the introduction of multiparametric magnetic resonance imaging (mpMRI). mpMRI consists of T2-weighted sequences combined with several functional sequences including diffusion-weighted imaging, dynamic contrast-enhanced imaging, and/or magnetic resonance spectroscopy imaging. Interest has been growing in mpMRI because no single MRI sequence adequately detects and characterizes prostate cancer. During the last decade, the role of mpMRI has been expanded in prostate cancer detection, staging, and targeting or guiding prostate biopsy. Recently, mpMRI has been used to assess prostate cancer aggressiveness and to identify anteriorly located tumors before and during active surveillance. Moreover, recent studies have reported that mpMRI is a reliable imaging modality for detecting local recurrence after radical prostatectomy or external beam radiation therapy. In this regard, some urologic clinical practice guidelines recommended the use of mpMRI in the diagnosis and management of prostate cancer. Because mpMRI is the evolving reference standard imaging modality for prostate cancer, urologists should acquire cutting-edge knowledge about mpMRI. In this article, we review the literature on the use of mpMRI in urologic practice and provide a brief description of techniques. More specifically, we state the role of mpMRI in prostate biopsy, active surveillance, high-risk prostate cancer, and detection of recurrence after radical prostatectomy.

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.

Twelve Core Template Prostate Biopsy is an Unreliable Tool to Select Patients Eligible for Focal Therapy

Introduction: To determine whether unilateral prostate cancer diagnosed at 12-core prostate biopsy harbours relevant prostate cancer foci in contralateral lobe in cases eligible for hemiablative focal therapy. Material and Methods: We analysed 112 radical prostatectomies of unilateral Gleason 6/7 prostate cancer based on prostate biopsy information. The presence of significant prostate cancer foci and/or the index lesion in the contralateral lobe is described. A subanalysis is performed in cases of Gleason score 6 and in cases of very-low-risk prostate cancer. Results: Contralateral prostate cancer was present in 69.6% of cases, fulfilling significant prostate cancer criteria in 33% and being the index lesion in 32%. No significant differences were found when analysing the Gleason 6 group (73% contralateral prostate cancer, 34% significant prostate cancer and 35% index lesion) or the very-low-risk prostate cancer group (80% contralateral prostate cancer, 29% significant prostate cancer and 45% index lesion). Conclusions: The assumption of unilateral prostate cancer based on 12-core template prostate biopsy information is unreliable. In about one third of the cases, there will be focus of significant prostate cancer or the index lesion in the contralateral lobe. This information should be taken into account when hemiablative focal therapies are considered.