Direct MRI-guided In-Bore Targeted Biopsy of the Prostate: A Step-by-Step How To and Lessons Learned.

Multiparametric MRI-the most accurate imaging technique for detection of prostate cancer-has transformed the landscape of prostate cancer diagnosis by enabling targeted biopsies. In a targeted biopsy, tissue samples are obtained from suspicious regions identified at prebiopsy diagnostic MRI. The authors briefly compare the different strategies available for targeting an MRI-visible suspicious lesion, followed by a step-by-step description of the direct MRI-guided in-bore approach and an illustrated review of its application in challenging clinical scenarios. In this technique, direct visualization of the needle, needle guide, and needle trajectory during the procedure provides a precise and versatile strategy to accurately sample suspicious lesions, improving detection of clinically significant cancers. Published under a CC BY 4.0 license Test Your Knowledge questions for this article are available in the supplemental material.

Preoperative Multiparametric Prostate Magnetic Resonance Imaging Structured Report Informs Risk for Positive Apical Surgical Margins During Radical Prostatectomy.

BACKGROUND: The prostatic apex is the most frequent location of positive surgical margin (PSM) after surgery. Data regarding the ability of multiparametric magnetic resonance imaging (mpMRI) to prospectively identify men at risk for apical PSMs (aPSMs) using a structured report are lacking. OBJECTIVES: The aims of the study are to determine and to compare the rate of aPSM in men with versus without prospectively flagged at-risk prostate lesions during clinical mpMRI interpretation using whole-mount histopathology as the reference standard. METHODS: This single-center, retrospective study of prospectively collected data included treatment-naive men with abnormal 3T mpMRI (PI-RADS v2 score ≥3) between January 2016 and December 2018 followed by surgery. During routine clinical interpretation, radiologists flagged prostate lesions abutting the apical most gland and/or encircling the distal most prostatic urethra using standardized language available as a "pick list" option in the structured report. Logistic regression was used to compare the rate of PSM in 2 groups (flagged vs nonflagged men). Propensity score covariate adjustment corrected for potential selection bias according to age, prostate-specific antigen (PSA), PSA density, grade group, and pT stage. The estimate was further adjusted by including surgeon as a covariate. RESULTS: A total of 428 men were included. A statistically significant higher proportion of aPSMs was noted in flagged (56% [51/91]) compared with nonflagged apical lesions (31% [105/337]; adjusted odds ratio, 2.5; 95% confidence interval, 1.6-4.1; P < 0.01). The difference in aPSM between both groups also varied according to the surgeon performing the RP. Prostate-specific antigen, PSA density, lesion size, apical location, Prostate Imaging Reporting & Data System score, grade group, pT stage, and surgeon's experience were associated with higher PSM rate. Biochemical recurrence, defined as PSA greater than 0.2 ng/mL on 2 measurements after RP, was significantly associated with PSM status (propensity score adjusted odds ratio, 3.1; 95% confidence interval, 1.8-5.3; P < 0.0001); however, patients flagged by radiologists did not have a significant difference in biochemical recurrence rates as compared with nonflagged patients ( P = 0.11). CONCLUSIONS: Standard language built into structured reports for mpMRI of the prostate helps identify preoperatively patients at risk for aPSM. CLINICAL IMPACT: Multiparametric MRI is able to identify patients at increased risk for aPSM, and this information can be conveyed in a structured report to urologists, facilitating patient counseling and treatment decisions.

Magnetic Resonance Imaging-Guided Transurethral Ultrasound Ablation of Prostate Cancer.

PURPOSE: Magnetic resonance imaging-guided transurethral ultrasound ablation uses directional thermal ultrasound under magnetic resonance imaging thermometry feedback control for prostatic ablation. We report 12-month outcomes from a prospective multicenter trial (TACT). MATERIALS AND METHODS: A total of 115 men with favorable to intermediate risk prostate cancer across 13 centers were treated with whole gland ablation sparing the urethra and apical sphincter. The co-primary 12-month endpoints were safety and efficacy. RESULTS: In all, 72 (63%) had grade group 2 and 77 (67%) had NCCN® intermediate risk disease. Median treatment delivery time was 51 minutes with 98% (IQR 95-99) thermal coverage of target volume and spatial ablation precision of ±1.4 mm on magnetic resonance imaging thermometry. Grade 3 adverse events occurred in 9 (8%) men. The primary endpoint (U.S. Food and Drug Administration mandated) of prostate specific antigen reduction ≥75% was achieved in 110 of 115 (96%) with median prostate specific antigen reduction of 95% and nadir of 0.34 ng/ml. Median prostate volume decreased from 37 to 3 cc. Among 68 men with pretreatment grade group 2 disease, 52 (79%) were free of grade group 2 disease on 12-month biopsy. Of 111 men with 12-month biopsy data, 72 (65%) had no evidence of cancer. Erections (International Index of Erectile Function question 2 score 2 or greater) were maintained/regained in 69 of 92 (75%). Multivariate predictors of persistent grade group 2 at 12 months included intraprostatic calcifications at screening, suboptimal magnetic resonance imaging thermal coverage of target volume and a PI-RADS™ 3 or greater lesion at 12-month magnetic resonance imaging (p <0.05). CONCLUSIONS: The TACT study of magnetic resonance imaging-guided transurethral ultrasound whole gland ablation in men with localized prostate cancer demonstrated effective tissue ablation and prostate specific antigen reduction with low rates of toxicity and residual disease.

Prospective PI-RADS v2.1 Atypical Benign Prostatic Hyperplasia Nodules With Marked Restricted Diffusion: Detection of Clinically Significant Prostate Cancer on Multiparametric MRI.

BACKGROUND. On the basis of expert consensus, PI-RADS version 2.1 (v2.1) introduced the transition zone (TZ) atypical benign prostatic hyperplasia (BPH) nodule, defined as a TZ lesion with an incomplete or absent capsule (T2 score, 2). PI-RADS v2.1 also included a revised scoring pathway whereby such nodules, if exhibiting marked restricted diffusion (DWI score, 4-5), are upgraded from overall PI-RADS category 2 to category 3 (2 + 1 TZ lesions). OBJECTIVE. The purpose of this study was to compare the rates of detection of clinically significant prostate cancer (csPCa) in prospectively reported 2 + 1 TZ lesions, as defined by PI-RADS v2.1, and conventional 3 + 0 TZ lesions with targeted biopsy as the reference standard. METHODS. This retrospective study included men with no known PCa or with treatment-naïve grade group (GG) 1 PCa who underwent 3-T multiparametric MRI of the prostate with prospective reporting by means of PI-RADS v2.1. Patients with at least one PI-RADS category 3 TZ lesion who underwent targeted biopsy formed the final sample. Biopsy results were summarized descriptively for 2 + 1 and 3 + 0 lesions. Generalized estimating equations were used to compare csPCa detection rates between groups. Associations between csPCa in 2 + 1 lesions and patient age, PSA level, prostate volume, PSA density, biopsy history, lesion size, and lesion ADC were tested with Kruskal-Wallis and Fisher exact tests. RESULTS. Among 1238 eligible patients who underwent MRI reported with PI-RADS v2.1, 2 + 1 lesions were reported in 6% (n = 69) and 3 + 0 TZ lesions in 7% (n = 87) of patients. No PCa, GG1 PCa, or csPCa was found in 84% (n = 41), 10% (n = 5), and 6% (n = 3) of 49 patients with 2 + 1 lesions who underwent targeted biopsy. Nor were they found in 74% (n = 45), 15% (n = 9), and 11% (n = 7) of 61 patients with 3 + 0 lesions who underwent targeted biopsy. The csPCa detection rate was not significantly different between 2 + 1 and 3 + 0 lesions (p = .31). All cases of csPCa were GG2, except for one 3 + 0 lesion with a GG3 tumor. No clinical or imaging variable was associated with csPCa in 2 + 1 lesions. CONCLUSION. The rate of csPCa in atypical BPH nodules with marked restricted diffusion was low (6%) and not significantly different from that of conventional 3 + 0 TZ lesions (11%). CLINICAL IMPACT. The results provide prospective clinical data about the revised TZ scoring criterion and pathway in PI-RADS v2.1 for atypical BPH nodules with marked restricted diffusion.

Impact of the Number of Cores on the Prostate Cancer Detection Rate in Men Undergoing in-Bore Magnetic Resonance Imaging-Guided Targeted Biopsies.

OBJECTIVE: To determine the incremental detection rate of clinically significant prostate cancer (csPCa) provided by sequential cores during in-bore magnetic resonance imaging (MRI)-guided prostate biopsies. METHODS: Single-center, retrospective interpretation of prospectively acquired data in men without previous diagnosis of csPCa who underwent in-bore MRI-guided prostate biopsy between May 2017 and December 2019. Endpoints included detection of csPCa (grade group [GG] ≥ 2) and rate of GG upgrade provided by additional cores. Descriptive statistics presented as mean and standard deviation for the continuous variables, and frequency and percentage for the categorical variables. RESULTS: Four hundred and forty-three men with 747 lesions met eligibility criteria. Clinically significant prostate cancer was detected in 43.1% (322/747) of the biopsied lesions and GG 2 PCa or greater was identified by the first core in 78.3% (252/322) of them. On a per-core basis, cores 2, 3, 4, and 5 found new csPCa in 6% (42/744), 4% (26/719), 1% (2/137), and 0% (0/11) of the cases. Core biopsy 2, 3, 4, and 5 resulted in GG upgrade in 12% (91/744), 7% (49/719), 7% (9/137), and 0% (0/11) of the lesions, respectively. Each additional core was associated with a mean increase of 5 minutes in the duration of the biopsy. CONCLUSIONS: In men undergoing in-bore MRI-guided prostate biopsies, 3 targeted cores per lesion provide an optimal trade-off between detection of clinically significant tumors and biopsy duration.

Turbo Spin-Echo Diffusion-Weighted Imaging in Prostate Magnetic Resonance Imaging of Men With Pelvic Hardware.

We evaluated an alternative diffusion-weighted imaging (DWI) acquisition for prostate magnetic resonance imaging of men with pelvic hardware, using radial k-space sampling (MultiVane [MV]), short-tau inversion-recovery (STIR) fat suppression, and split acquisition of turbo spin-echo signals. The optimized STIR-MV-DWI reduced metal-associated artifacts and image distortion, and aided in visualization of the prostate and lesions. The STIR-MV-DWI can be a valuable adjunct in prostate magnetic resonance imaging of men with pelvic hardware, among whom the conventional echo-planar DWI is compromised.

Diagnostic Performance of Prospectively Assigned Likert Scale Scores to Determine Extraprostatic Extension and Seminal Vesicle Invasion With Multiparametric MRI of the Prostate.

OBJECTIVE: The objective of this study was to determine the diagnostic performance of a prospectively assigned 5-point Likert scale for determination of extraprostatic extension (EPE) and seminal vesicle invasion (SVI). MATERIALS AND METHODS: This study was a single-center, retrospective analysis of prospectively collected data including all men with abnormal 3-T multiparametric MRI and subsequent radical prostatectomy between November 1, 2016, and September 30, 2017. Scores from a 5-point subjective Likert scale (1 = highly unlikely, 5 = highly likely) for the likelihood of EPE and SVI were prospectively assigned during clinical MRI interpretation. EPE and SVI status at whole-mount prostatectomy specimen served as the standard of reference. RESULTS: Among the 89 eligible men, whole-mount histopathology revealed organ-confined prostate cancer, EPE, and SVI in 49% (44/89), 46% (41/89), and 18% (16/89) of patients, respectively. Of the pathologically proven cases of EPE, 18% (2/11), 17% (4/24), 65% (17/26), 46% (6/13) and 80% (12/15) were assigned Likert scores of 1-5, respectively. Of the pathologically proven cases of SVI, 5% (3/58), 11% (2/18), 66% (2/3), 66% (2/3) and 100% (7/7) were assigned Likert scores of 1-5, respectively. The positive predictive values for scores of 4 or 5 were 64% for EPE and 90% for SVI. The negative predictive values for scores of 1 or 2 were 87% for EPE and 93% for SVI. Likert scores for EPE (odds ratio, 2.1; 95% CI, 1.3-3.4) and for SVI (odds ratio, 4.7; 95% CI, 2.3-9.6) were both associated with EPE and SVI on multivariate analysis. CONCLUSION: A 5-point Likert scale can effectively convey the degree of suspicion of EPE and SVI on multiparametric MRI of the prostate, facilitating informed decision-making.

Prospective Inclusion of Apparent Diffusion Coefficients in Multiparametric Prostate MRI Structured Reports: Discrimination of Clinically Insignificant and Significant Cancers.

OBJECTIVE: The purpose of this study was to assess the diagnostic performance of prospectively assigned mean apparent diffusion coefficient (ADC) values in multiparametric MRI (mpMRI) structured reports for discriminating clinically insignificant (International Society of Urological Pathology [ISUP] group 1) from clinically significant (ISUP groups 2-5) prostate cancer. MATERIALS AND METHODS: This single-center study included men with abnormal 3-T mpMRI findings (Prostate Imaging Reporting and Data System version 2 score, ≥ 3) who subsequently underwent radical prostatectomy or targeted biopsy with positive results. One of nine radiologists prospectively reported the mean ADC for each lesion during clinical interpretation. Lesions with ADC ≤ 0.700 mm2/s × 10-3 were flagged as concerning for clinically significant prostate cancer. The index lesion at MRI correlated with the site-concordant lesion at targeted biopsy or whole-mount histopathologic analysis. Logistic regression was used to evaluate the utility of mean ADC values for discriminating ISUP grade group 1 from groups 2-5. Diagnostic performance was assessed by ROC AUC. RESULTS: Among the 218 eligible men, those with ISUP group 2-5 lesions had lower mean ADC values than those with ISUP 1 lesions; overall, 0.598 vs 0.803 mm/s2 × 10-3 (p < 0.0001); peripheral zone (PZ), 0.597 vs 0.855 mm/s2 × 10-3 (p < 0.0001); transition zone (TZ), 0.600 vs 0.660 mm/s2 × 10-3 (p = 0.035). The AUC for the PZ was 0.91 and for the TZ was 0.70. The optimal ADC cutoff values were 0.682 mm/s2 × 10-3 for PZ lesions and 0.638 mm2/s × 10-3 for TZ lesions, resulting in sensitivity and specificity of 78% and 94% for the PZ and 72% and 67% for the TZ. CONCLUSION: ADC values estimated prospectively in a clinical setting can help differentiate clinically insignificant from clinically significant prostate cancer, facilitating prebiopsy and pretreatment risk stratification.

Current Challenges in Diagnosis and Assessment of the Response of Locally Advanced and Metastatic Renal Cell Carcinoma.

Locally advanced and metastatic renal cell carcinoma (RCC) present a specific set of challenges to the radiologist. The detection of metastatic disease is confounded by the ability of RCC to metastasize to virtually any part of the human body long after surgical resection of the primary tumor. This includes sites not commonly included in routine surveillance, which come to light after the patient becomes symptomatic. In the assessment of treatment response, the phenomenon of tumor heterogeneity, where clone selection through systemic therapy drives the growth of potentially more aggressive phenotypes, can result in oligoprogression despite overall disease control. Finally, advances in therapy have resulted in the development of immuno-oncologic agents that may result in changes that are not adequately evaluated with conventional size-based response criteria and may even be misinterpreted as progression. This article reviews the common challenges a radiologist may encounter in the evaluation of patients with locally advanced and metastatic RCC. ©RSNA, 2019.

Case 258: Granulomatous Prostatitis.

History A 68-year-old man with a remote history of a previously resected high-grade urothelial carcinoma in the renal pelvis was being observed and was undergoing urologic treatment for recurrent low-grade urothelial carcinoma of the bladder. During his most recent evaluation, he reported no specific symptoms and denied experiencing hematuria, dysuria, or abdominal pain. At routine surveillance MRI of the abdomen and pelvis (images not shown), a lesion was noted in the peripheral zone of the prostate gland. The prostate-specific antigen level was elevated (7.51 ng/mL [normal range, 0.00-4.00 ng/mL]). The patient had no family history of prostate cancer and had never undergone prostate biopsy. MRI of the prostate with an endorectal coil was subsequently performed.

Diagnostic Performance and Interreader Agreement of a Standardized MR Imaging Approach in the Prediction of Small Renal Mass Histology.

Purpose To assess the diagnostic performance and interreader agreement of a standardized diagnostic algorithm in determining the histologic type of small (≤4 cm) renal masses (SRMs) with multiparametric magnetic resonance (MR) imaging. Materials and Methods This single-center retrospective HIPAA-compliant institutional review board-approved study included 103 patients with 109 SRMs resected between December 2011 and July 2015. The requirement for informed consent was waived. Presurgical renal MR images were reviewed by seven radiologists with diverse experience. Eleven MR imaging features were assessed, and a standardized diagnostic algorithm was used to determine the most likely histologic diagnosis, which was compared with histopathology results after surgery. Interreader variability was tested with the Cohen κ statistic. Regression models using MR imaging features were used to predict the histopathologic diagnosis with 5% significance level. Results Clear cell renal cell carcinoma (RCC) and papillary RCC were diagnosed, with sensitivities of 85% (47 of 55) and 80% (20 of 25), respectively, and specificities of 76% (41 of 54) and 94% (79 of 84), respectively. Interreader agreement was moderate to substantial (clear cell RCC, κ = 0.58; papillary RCC, κ = 0.73). Signal intensity (SI) of the lesion on T2-weighted MR images and degree of contrast enhancement (CE) during the corticomedullary phase were independent predictors of clear cell RCC (SI odds ratio [OR]: 3.19; 95% confidence interval [CI]: 1.4, 7.1; P = .003; CE OR, 4.45; 95% CI: 1.8, 10.8; P < .001) and papillary RCC (CE OR, 0.053; 95% CI: 0.02, 0.2; P < .001), and both had substantial interreader agreement (SI, κ = 0.69; CE, κ = 0.71). Poorer performance was observed for chromophobe histology, oncocytomas, and minimal fat angiomyolipomas, (sensitivity range, 14%-67%; specificity range, 97%-99%), with fair to moderate interreader agreement (κ range = 0.23-0.43). Segmental enhancement inversion was an independent predictor of oncocytomas (OR, 16.21; 95% CI: 1.0, 275.4; P = .049), with moderate interreader agreement (κ = 0.49). Conclusion The proposed standardized MR imaging-based diagnostic algorithm had diagnostic accuracy of 81% (88 of 109) and 91% (99 of 109) in the diagnosis of clear cell RCC and papillary RCC, respectively, while achieving moderate to substantial interreader agreement among seven radiologists. © RSNA, 2018 Online supplemental material is available for this article.

Reproducibility of Index Lesion Size and Mean Apparent Diffusion Coefficient Values Measured by Prostate Multiparametric MRI: Correlation With Whole-Mount Sectioning of Specimens.

OBJECTIVE: The purpose of this study is to determine the intra- and interreader agreement for index lesion size and mean apparent diffusion coefficient (ADC) value measurements performed by five readers using whole-mount histopathologic specimens processed with a patient-specific, MRI-based, 3D-printed mold as the standard of reference. MATERIALS AND METHODS: All men who underwent multiparametric MRI of the prostate performed using a 3-T scanner with endorectal and phased-array surface coils, followed by prostatectomy conducted between November 2015 and July 2016 at our institution, were identified. MRI examinations were independently reviewed by five readers with varying degrees of experience, two of whom had essentially no experience in prostate MRI interpretation before the study, to assess index lesion size and ADC values. A linear mixed model-based intraclass correlation was used to assess intra- and interreader reader agreement for lesion size and ADC measurements and agreement for size measurements between pathologic analysis and readers. RESULTS: A total of 80 men met the study eligibility criteria. Overall inter- and intrareader agreement for ADC measurements was excellent, with interclass correlation coefficient (ICC) values of 0.84 and 0.90, respectively; both inter- and intrareader agreement between experienced readers (0.82 and 0.92, respectively) and inexperienced readers (0.86 and 0.87, respectively) were excellent as well. The agreement between mean lesion size on imaging and histopathologic analysis ranged from poor (0.32) to good (0.66), with overall agreement considered fair (0.49). CONCLUSION: Readers with varying degrees of experience achieved good-to-excellent agreement for index lesion size and ADC values on multiparametric MRI of men with prostate cancer. This degree of reproducibility may improve preoperative risk stratification, informed decision making, and treatment planning for men with known or suspected prostate cancer.

Diagnostic Utility of a Likert Scale Versus Qualitative Descriptors and Length of Capsular Contact for Determining Extraprostatic Tumor Extension at Multiparametric Prostate MRI.

OBJECTIVE: The purpose of this study is to determine the reproducibility and diagnostic performance of a Likert scale in comparison with the European Society of Urogenital Radiology (ESUR) criteria and tumor-pseudocapsule contact length (TCL) for the detection of extraprostatic extension (EPE) at multiparametric MRI. MATERIALS AND METHODS: This was a retrospective review of all men who underwent multiparametric MRI followed by prostatectomy between November 2015 and July 2016. Multiparametric 3-T MRI studies with an endorectal coil were independently reviewed by five readers who assigned the likelihood of EPE using a 1-5 Likert score, ESUR criteria, and TCL (> 10 mm). EPE outcome (absent or present) for the index lesion at whole-mount histopathologic analysis was the standard of reference. Odds ratios (ORs) and areas under the ROC curve (Az) were used for diagnostic accuracy. The interreader agreement was determined using a weighted kappa coefficient. A p < 0.05 was considered significant. RESULTS: Eighty men met the eligibility criteria. At univariate analysis, the Likert score showed the strongest association (OR, 1.8) with EPE, followed by prostate-specific antigen level (OR, 1.7), ESUR score (OR, 1.6), and index lesion size (OR, 1.2). At multivariable analysis, higher Likert score (OR, 1.8) and prostate-specific antigen level (OR, 1.6-1.7) were independent predictors of EPE. The Az value for Likert scores was statistically significantly higher (0.79) than that for TCL (0.74; p < 0.01), but not statistically significantly higher than the value for ESUR scores (0.77; p = 0.17). Interreader agreement with Likert (κ = 0.52) and ESUR scores (κ = 0.55) was moderate and slightly superior to that for TCL (κ = 0.43). Except for TCL among inexperienced readers (κ = 0.34), reader experience did not affect interreader agreement. CONCLUSION: A Likert score conveying the degree of suspicion at multiparametric MRI is a stronger predictor of EPE than is either ESUR score or TCL and may facilitate informed decision making, patient counseling, and treatment planning.

Targeting phenotypic heterogeneity in benign prostatic hyperplasia.

Benign prostatic hyperplasia and associated lower urinary tract symptoms remain difficult to treat medically, resulting in hundreds of thousands of surgeries performed annually in elderly males. New therapies have not improved clinical outcomes since alpha blockers and 5 alpha reductase inhibitors were introduced in the 1990s. An underappreciated confounder to identifying novel targets is pathological heterogeneity. Individual patients display unique phenotypes, composed of distinct cell types. We have yet to develop a cellular or molecular understanding of these unique phenotypes, which has led to failure in developing targeted therapies for personalized medicine. This review covers the strategic experimental approach to unraveling the cellular pathogenesis of discrete BPH phenotypes and discusses how to incorporate these findings into the clinic to improve outcomes.

Quantitative diffusion-weighted imaging and dynamic contrast-enhanced characterization of the index lesion with multiparametric MRI in prostate cancer patients.

PURPOSE: To compare a simplified intravoxel incoherent motion (sIVIM) model to commonly used monoexponential and biexponential models in the characterization of prostate cancer (PCa) and noncancerous prostate tissues, and to investigate combinations of diffusion-weighted imaging (DWI) measures with dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI)-derived parameters in MRI-visible index lesions, to facilitate PCa risk stratification. MATERIALS AND METHODS: In this retrospective, Institutional Review Board (IRB)-approved study, 43 consecutive patients with PCa who had 3T MRI exams followed by radical prostatectomy were included. DWI and DCE parameters were measured from one index lesion per patient, and noncancerous central gland and peripheral zone. Logistic regression modeling was performed to select the optimal combination of DWI and DCE measurements for tumor risk assessment. RESULTS: All diffusion models showed the lowest diffusion coefficients in tumors, intermediate values in noncancerous central gland, and highest values in noncancerous peripheral zone (all P < 0.001). Ktrans and kep were higher in tumors compared to central gland (P < 0.005) and peripheral zone (P < 0.001). The initial area under the contrast concentration curve was higher in tumor than the peripheral zone (P < 0.001). The area under the receiver operating characteristic curve of the combined DWI and DCE parameters (0.78) was higher than its individual components (0.73 and 0.63, respectively) for discriminating low- and intermediate-to-high-risk tumors. CONCLUSION: The sIVIM model provided comparable results with fewer b-values and shorter image acquisition time. The combination of DWI and DCE measurements of MRI-visible index lesions improved the preoperative prostate cancer risk characterization compared to the individual parameters from either technique alone. LEVEL OF EVIDENCE: 3 J. Magn. Reson. Imaging 2017;45:908-916.

Assessment of Prospectively Assigned Likert Scores for Targeted Magnetic Resonance Imaging-Transrectal Ultrasound Fusion Biopsies in Patients with Suspected Prostate Cancer.

PURPOSE: We assess the performance of prospectively assigned magnetic resonance imaging based Likert scale scores for the detection of clinically significant prostate cancer, and analyze the pre-biopsy imaging variables associated with increased cancer detection using targeted magnetic resonance imaging-transrectal ultrasound fusion biopsy. MATERIALS AND METHODS: In this retrospective review of prospectively generated data including men with abnormal multiparametric prostate magnetic resonance imaging (at least 1 Likert score 3 or greater lesion) who underwent subsequent targeted magnetic resonance imaging-transrectal ultrasound fusion biopsy, we determined the association between different imaging variables (Likert score, lesion size, lesion location, prostate volume, radiologist experience) and targeted biopsy positivity rate. We also compared the detection of clinically significant cancer according to Likert scale scores. Tumors with high volume (50% or more of any core) Gleason score 3+4 or any tumor with greater Gleason score were considered clinically significant. Each lesion served as the elementary unit for analysis. We used logistic regression for univariate and multivariate (stepwise selection) analysis to assess for an association between targeted biopsy positivity rate and each tested variable. The relationship between Likert scale and Gleason score was evaluated using the Spearman correlation coefficient. RESULTS: A total of 161 men with 244 lesions met the study eligibility criteria. Targeted biopsies diagnosed cancer in 41% (66 of 161) of the men and 41% (99 of 244) of the lesions. The Likert score was the strongest predictor of targeted biopsy positivity (OR 3.7, p <0.0001). Other imaging findings associated with a higher targeted biopsy positivity rate included smaller prostate volume (OR 0.7, p <0.01), larger lesion size (OR 2.2, p <0.001) and anterior location (OR 2.0, p=0.01). On multiple logistic regression analysis Likert score, lesion size and prostate volume were significant predictors of targeted biopsy positivity. Higher Likert scores were also associated with increased detection of clinically significant tumors (p <0.0001). CONCLUSIONS: The Likert scale score used to convey the degree of suspicion on multiparametric magnetic resonance imaging is the strongest predictor of targeted biopsy positivity and of the presence of clinically significant tumor.