Is MRI ready to replace biopsy during active surveillance?

Active surveillance (AS) is a conservative management option recommended for patients diagnosed with low-risk prostate cancer (PCa) and selected cases with intermediate-risk PCa. The adoption of prostate MRI in the primary diagnostic setting has sparked interest in its application during AS. This review aims to examine the role and performance of multiparametric MRI (mpMRI) across the entire AS pathway, from initial stratification to follow-up, also relative to the utilization of the Prostate Cancer Radiological Estimation of Change in Sequential Evaluation (PRECISE) criteria. Given the high negative predictive value of mpMRI in detecting clinically significant PCa (csPCa), robust evidence supports its use in patient selection and risk stratification at the time of diagnosis or confirmatory biopsy. However, conflicting results have been observed when using MRI in evaluating disease progression during follow-up. Key areas requiring clarification include addressing the clinical significance of MRI-negative csPCa, optimizing MRI quality, determining the role of biparametric MRI (bpMRI) or mpMRI protocols, and integrating artificial intelligence (AI) for improved performance. CLINICAL RELEVANCE STATEMENT: MRI plays an essential role in the selection, stratification, and follow up of patients in active surveillance (AS) for prostate cancer. However, owing to existing limitations, it cannot fully replace biopsies in the context of AS. KEY POINTS: Multiparametric MRI (mpMRI) has become a crucial tool in active surveillance (AS) for prostate cancer (PCa). Conflicting results have been observed regarding multiparametric MRI efficacy in assessing disease progression. Standardizing MRI-guided protocols will be critical in addressing current limitations in active surveillance for prostate cancer.

Prostate Magnetic Resonance Imaging Using the Prostate Imaging for Recurrence Reporting (PI-RR) Scoring System to Detect Recurrent Prostate Cancer: A Systematic Review and Meta-analysis.

BACKGROUND AND OBJECTIVE: Prostate Imaging for Recurrence Reporting (PI-RR) was introduced in 2021 to standardize the interpretation and reporting of multiparametric magnetic resonance imaging (MRI) for prostate cancer following whole-gland treatment. The system scores image on a scale from 1 to 5 and has shown promising results in single-center studies. The aim of our systematic review and meta-analysis was to assess the diagnostic performance of the PI-RR system in predicting the likelihood of local recurrence after whole-gland treatment. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for diagnostic test accuracy were followed. Relevant databases were searched up to December 2023. Primary studies met the eligibility criteria if they reported MRI diagnostic performance in prostate cancer recurrence using PI-RR. Diagnostic performance for MRI was assessed using two different cutoff points (≥3 or ≥4 for positivity according to the PI-RR system). A meta-analysis with a random-effects model was used to estimate pooled sensitivity and specificity values. KEY FINDINGS AND LIMITATIONS: Sixteen articles were identified for full-text reading, of which six were considered eligible, involving a total of 467 patients. Using a cutoff of PI-RR ≥3 (4 studies) for recurrent disease, the sensitivity was 77.8% (95% confidence interval [CI] 69.9-84.1%) and the specificity was 80.2% (95% CI 58.2-92.2%). Using a cutoff of PI-RR ≥4 (4 studies), the sensitivity was 61.9% (95% CI 35.6-82.7%) and the specificity was 86.6% (95% CI 75.1-93.3%). Overall, the inter-rater agreement varied from fair to excellent. CONCLUSIONS AND CLINICAL IMPLICATIONS: PI-RR is accurate in detecting local recurrence after whole-gland treatment for prostate cancer and shows fair-to-good to excellent inter-reader agreement. Overall, a PI-RR cutoff of ≥3 showed high sensitivity and specificity. PATIENT SUMMARY: We reviewed studies that reported on how good MRI scans using a scoring system called PI-RR were in detecting recurrence of prostate cancer. We found that this system shows good performance, with fair to excellent agreement between different radiologists.

Comparison of Multiparametric MRI and the Combination of PSMA Plus MRI for the Intraprostatic Diagnosis of Prostate Cancer: A Systematic Review and Meta-Analysis.

PURPOSE: The aim of this study was to perform a head-to-head comparison of multiparametric MRI (mpMRI) and the combination of prostate-specific membrane antigen (PSMA) PET plus MRI (PSMA + MRI) for detecting intraprostatic clinically significant prostate cancer (csPCa). PATIENTS AND METHODS: Relevant databases were searched through November 2023. Only studies directly comparing mpMRI and PSMA + MRI (PET/MRI or PET/CT + mpMRI) were included. A meta-analysis with a random-effects model was used to estimate pooled sensitivity, specificity, and area under the curve for each approach. RESULTS: A total of 19 studies were included. On a patient-level analysis, PSMA + MRI had higher sensitivity (9 studies) than mpMRI for csPCa detection (96% [95% confidence interval (CI): 92%, 98%] vs 89% [95% CI: 81%, 94%]; P = 0.04). The patient-level specificity (4 studies) of PSMA + MRI was 55% (95% CI: 31%-76%) compared with 50% (95% CI: 44%-57%) of mpMRI ( P = 0.67). Region-level sensitivity (10 studies) was 85% (95% CI: 74%-92%) for PSMA + MRI and 71% (95% CI: 58%-82%) for mpMRI ( P = 0.09), whereas specificity (4 studies) was 87% (95% CI: 76%-94%) and 90% (95% CI: 82%-95%), respectively ( P = 0.59). Lesion-level sensitivity and specificity were similar between modalities with pooled data from less than 4 studies. CONCLUSIONS: PSMA + MRI had superior pooled sensitivity and similar specificity for the detection of csPCa compared with mpMRI in this meta-analysis of head-to-head studies.

New Prostate MRI Scoring Systems (PI-QUAL, PRECISE, PI-RR, and PI-FAB): AJR Expert Panel Narrative Review.

Multiparametric MRI (mpMRI), interpreted using PI-RADS, improves the initial detection of clinically significant prostate cancer (PCa). Prostate MR image quality has increasingly recognized relevance to the use of mpMRI for PCa diagnosis. Additionally, mpMRI is increasingly used in scenarios beyond initial detection, including active surveillance and assessment for local recurrence after prostatectomy, radiation therapy, or focal therapy. Acknowledging these evolving demands, specialized prostate MRI scoring systems beyond PI-RADS have emerged, to address distinct scenarios and unmet needs. Examples include Prostate Imaging Quality (PI-QUAL) for assessment of image quality of mpMRI, Prostate Cancer Radiologic Estimation of Change in Sequential Evaluation (PRECISE) recommendations for evaluation of serial mpMRI examinations during active surveillance, Prostate Imaging for Recurrence Reporting System (PI-RR) for assessment for local recurrence after prostatectomy or radiation therapy, and Prostate Imaging after Focal Ablation (PI-FAB) for assessment for local recurrence after focal therapy. These systems' development and early uptake signal a compelling shift towards prostate MRI standardization in different scenarios, and ongoing research will help refine their roles in practice. This AJR Expert Panel Narrative Review critically examines these new prostate MRI scoring systems (PI-QUAL, PRECISE, PI-RR, and PI-FAB), analyzing the available evidence, delineating current limitations, and proposing solutions for improvement.

Decision Regret Following the Choice of Surgery or Active Surveillance for Small, Low-Risk Papillary Thyroid Cancer: A Prospective Cohort Study.

Background: It is important to understand cancer survivors' perceptions about their treatment decisions and quality of life. Methods: We performed a prospective observational cohort study of Canadian patients with small (<2 cm) low-risk papillary thyroid cancer (PTC) who were offered the choice of active surveillance (AS) or surgery (Clinicaltrials.gov NCT03271892). Participants completed a questionnaire one year after their treatment decision. The primary intention-to-treat analysis compared the mean decision regret scale total score between patients who chose AS or surgery. A secondary analysis examined one-year decision regret score according to treatment status. Secondary outcomes included quality of life, mood, fear of disease progression, and body image perception. We adjusted for age, sex, and follow-up duration in linear regression analyses. Results: The overall questionnaire response rate was 95.5% (191/200). The initial treatment choices of respondents were AS 79.1% (151/191) and surgery 20.9% (40/191). The mean age was 53 years (standard deviation [SD] 15 years) and 77% (147/191) were females. In the AS group, 7.3% (11/151) of patients crossed over to definitive treatment (two for disease progression) before the time of questionnaire completion. The mean level of decision regret did not differ significantly between patients who chose AS (mean 22.4, SD 13.9) or surgery (mean 20.9, SD 12.2) in crude (p = 0.730) or adjusted (p = 0.29) analyses. However, the adjusted level of decision regret was significantly higher in patients who initially chose AS and crossed over to surgery (beta coefficient 10.1 [confidence interval; CI 1.3-18.9], p = 0.02), compared with those remaining under AS. In secondary adjusted analyses, respondents who chose surgery reported that symptoms related to their cancer or its treatment interfered with life to a greater extent than those who chose AS (p = 0.02), but there were no significant group differences in the levels of depression, anxiety, fear of disease progression, or overall body image perception. Conclusions: In this study of patients with small, low-risk PTC, the mean level of decision regret pertaining to the initial disease management choice was relatively low after one year and it did not differ significantly for respondents who chose AS or surgery.

MRI-guided Focused Ultrasound Focal Therapy for Intermediate-Risk Prostate Cancer: Final Results from a 2-year Phase II Clinical Trial.

Background MRI-guided focal therapy (FT) allows for accurate targeting of localized clinically significant prostate cancer (csPCa) while preserving healthy prostate tissue, but the long-term outcomes of this approach require more study. Purpose To assess the 2-year oncological and functional outcomes of men with intermediate-risk prostate cancer (PCa) treated with targeted FT. Materials and Methods In this single-center prospective phase II trial, men with localized unifocal intermediate-risk PCa underwent transrectal MRI-guided focused ultrasound between July 2016 and July 2019. Planned ablation volumes included 10-mm margins when possible. Data regarding adverse events were collected and quality-of-life questionnaires were completed by participants at 6 weeks and at 5, 12, 18, and 24 months after treatment. Multiparametric MRI and targeted and systematic biopsies were performed at 24 months. Ablation volumes were determined by manual contouring of nonperfused volumes on immediate contrast-enhanced images. Generalized estimating equations were used to model trends in quality-of-life measures. Results Treatment was successfully completed in the 44 participants (median age, 67 years; IQR, 62-70 years; 36 patients with grade group [GG] 2; eight patients with GG 3). No major adverse events from treatment were recorded. One participant refused biopsy at 24 months. After 2 years, 39 of 43 participants (91%) had no csPCa at the treatment site and 36 of 43 (84%) had no cancer in the entire gland. No changes in International Index of Erectile Function-15 score or International Prostate Symptom Score were observed during 2-year follow-up (P = .73 and .39, respectively). Conclusion The majority of men treated with MRI-guided focused ultrasound for intermediate risk PCa had negative results for csPCa at biopsy 2 years after treatment. Additionally, there was no significant decline in quality of life per the validated questionnaires. Clinical trial registration no. NCT02968784 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Woodrum in this issue.

MRI-guided Minimally Invasive Focal Therapies for Prostate Cancer.

Two cases involving patients diagnosed with localized prostate cancer and treated with MRI-guided focal therapies are presented. Patient selection procedures, techniques, outcomes, challenges, and future directions of MRI-guided focal therapies, as well as their role in the treatment of low- to intermediate-risk localized prostate cancer, are summarized.

Magnetic Resonance Imaging-Targeted Versus Systematic Prostate Biopsies: 2-year Follow-up of a Prospective Randomized Trial (PRECISE).

BACKGROUND: The prospective randomized PRECISE trial demonstrated that magnetic resonance imaging (MRI) with only targeted biopsy (TBx) was noninferior to systematic transrectal ultrasound biopsy (SBx) in the detection of International Society of Urological Pathology grade group (GG) ≥2 prostate cancer (PC). An unanswered question is the outcome for patients who avoided a biopsy because of negative MRI findings. OBJECTIVE: To explore the rate of PC diagnosis based on 2-yr MRI for PRECISE participants who had no biopsy and for patients who had a negative result or GG 1 on TBx in comparison to those with a negative result or GG 1 on SBx. DESIGN, SETTING, AND PARTICIPANTS: The PRECISE prospective trial was conducted at five Canadian academic centers. The present analysis was for trial participants who were not diagnosed with clinically significant PC (csPC) at baseline. Of 453 randomized patients, 146 were diagnosed with GG ≥2 at baseline and were excluded. Eligible patients for this study included 83 men from the MRI arm who had negative MRI findings and no biopsy, 120 from the overall cohort who had a negative SBx or TBx, and 72 from the overall cohort who were diagnosed with GG 1 disease. INTERVENTION: MRI at 2 yr in all men in the MRI and SBx arms and TBx for lesions with a Prostate Imaging-Reporting and Data System score of ≥3 or on the basis of clinical suspicion. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was the proportion of men diagnosed with GG ≥2 cancer. Secondary outcomes included the MRI outcome and the proportion of men diagnosed with GG 1 PC. RESULTS AND LIMITATIONS: Evaluable 2-yr MRI scans were available for 75 (56%) eligible patients in the MRI arm and 69 (49%) in the SBx arm. Of these patients, 55 (73%) in the MRI arm and 51 (67%) SBx arm had negative 2-yr MRI. Of the 76 patients in the SBx arm with 2-yr MRI, 16 (21%) had a biopsy, for which the result was negative in eight (10%), GG1 in two (2.6%), and GG ≥2 in six (7.9%) cases. Of the 75 men in the MRI arm with 2-yr MRI, eight (11%) were biopsied, for which the result was negative in four cases (5%) and GG ≥2 in the other four (5%). At 2 yr, including baseline biopsy results, 116/221 (52.5%) in the MRI arm and 113/204 (55%) in the SBx arm were free of GG ≥2 disease, treatment, death from any cause, or progression (OR 1.08; p = 0.66). CONCLUSIONS: After 2-yr follow-up including MRI for patients in both arms of PRECISE, there was no difference in the rate of csPC diagnosis between the MRI and SBx groups, even though 38% of men in the MRI group avoided an initial biopsy. PATIENT SUMMARY: The PRECISE trial compared systematic biopsy of the prostate to a strategy of magnetic resonance imaging (MRI) with targeted biopsy of any lesions suspicious for cancer on the scan. After 2 years of follow-up that included 2-year MRI with or without biopsy in both groups, there was no difference in the rate of diagnosis of significant cancer, even though 38% of men in the initial MRI arm avoided an initial biopsy, and 30% avoided biopsy altogether. The PRECISE trial is registered on ClinicalTrials.gov as NCT02936258.

Impact of 18F-DCFPyL PET/MRI in Selecting Men With Low-/Intermediate-Risk Prostate Cancer for Focal Ablative Therapies.

PURPOSE: To compare the diagnostic performance of multiparametric (mp) MRI to 18F-DCFPyL PET/MRI for detecting clinically significant (cs) prostate cancer (PCa) in men with low-/intermediate-risk PCa being considered for focal ablative therapy (FT), using 2 interpretation schemes, and to assess the rate of exclusion from FT for each modality. METHODS: This prospective study evaluated men with low- or intermediate-risk PCa, potential candidates for FT based on initial biopsy as per institutional protocol, who underwent 18F-DCFPyL PET/MRI. Each modality (mpMRI, PET/MRI using PROMISE classification [PET/MRI PROMISE], and PET/MRI considering any focal lesion on PET as positive [PETFL/MRI]) was assessed independently. All suspicious lesions underwent PET/MRI-ultrasound fusion biopsies. Diagnostic performances were calculated and compared using the exact binomial test on paired proportions. RESULTS: Thirty-four men (median age, 64 years; interquartile range, 60-70 years) were included. Overall, 40 of 67 lesions (60%) identified on mpMRI and/or PET/MRI were malignant, and 34 of 40 lesions (85%) were csPCa (≥6 mm ISUP [International Society of Urological Pathology Grade Group] GG1 or ISUP-GG ≥2). On lesion-level analysis, for detecting csPCa, sensitivity appeared higher for PETFL/MRI than mpMRI and PET/MRI PROMISE (97% vs 76% and 79%, respectively [P = 0.02 and 0.03]), whereas specificity was lower (30% vs 85% and 88%, respectively [P < 0.001]). The calculated overall accuracy rates for PETFL/MRI, mpMRI, and PET/MRI PROMISE were 64%, 81%, and 84%, respectively. PETFL/MRI, mpMRI, and PET/MRI PROMISE excluded 10 of 34 (29%), 7 of 34 (21%), and 6 of 34 (18%) men from FT, respectively. CONCLUSIONS: 18F-DCFPyL PET/MRI excluded nearly 30% of patients with low-/intermediate-risk PCa from FT, with a potential role in decreasing selection failure. Compared with mpMRI, PET/MRI had a higher sensitivity for detecting csPCa in men who were candidates for FT.ClinicalTrials.gov identifier NCT03149861.

Inter-reader variability and reproducibility of the PI-QUAL score in a multicentre setting.

PURPOSE: To assess the inter-reader reproducibility of the Prostate Imaging Quality (PI-QUAL) score between readers with varying clinical experience and its reproducibility at assessing imaging quality between different institutions. METHODS: Following IRB approval, we assessed 60 consecutive prostate MRI scans performed at different academic teaching and non-academic hospitals uploaded to our institutes' PACS for second opinion or discussion in case conferences. Anonymized scans were independently reviewed using the PI-QUAL scoring sheet by three readers - two radiologists (with 1 and 12 years Prostate MRI reporting experience), and an experienced MRI technician with interest in image acquisition and quality. All readers were blinded to the site where scans were acquired. RESULTS: Agreement coefficients between the 3 readers in paired comparison for each individual PI-QUAL score was moderate. When the scans were clustered into 2 groups according to their ability to rule in or rule out clinically significant prostate cancer [i.e., PI-QUAL score 1-3 vs PI-QUAL score 4-5], the Gwet AC1 coefficients between the three readers in paired comparison was good to very good [Gwet AC 1:0.77, 0.67, 0.836 respectively] with agreement percentage of 88.3%, 83.3% and 91.7% respectively. Agreement coefficient was higher between the experienced radiologist and the experienced MRI technician than between the less experienced trainee radiologist and the other two readers. The mean PI-QUAL score provided by each reader for the scans was significantly higher in the academic hospitals (n = 32) compared to the community hospital (n = 28) [experienced radiologist 4.6 vs 2.9; trainee radiologist 4.5 vs 2.4; experienced technologist 4.4 vs 2.4; p value < 0.001]. CONCLUSION: We observed good to very good reproducibility in the assessment of each MRI sequence and when scans were clustered into two groups [PI-QUAL 1-3 vs PI-QUAL 4-5] between readers with varying clinical experience. However, the reproducibility for each single PI-QUAL score between readers was moderate. Better definitions for each PI-QUAL score criteria may further improve reproducibility between readers. Additionally, the mean PI-QUAL score provided by all three readers was significantly higher for scans performed at academic teaching hospitals compared to community hospital.

Gender Differences in Fears Related to Low-Risk Papillary Thyroid Cancer and Its Treatment.

Importance: Fear is commonly experienced by individuals newly diagnosed with papillary thyroid cancer (PTC). Objective: To explore the association between gender and fears of low-risk PTC disease progression, as well as its potential surgical treatment. Design, Setting, and Participants: This single-center prospective cohort study was conducted at a tertiary care referral hospital in Toronto, Canada, and enrolled patients with untreated small low risk PTC (<2 cm in maximal diameter) that was confined to the thyroid. All patients had a surgical consultation. Study participants were enrolled between May 2016 and February 2021. Data analysis was performed from December 16, 2022, to May 8, 2023. Exposures: Gender was self-reported by patients with low-risk PTC who were offered the choice of thyroidectomy or active surveillance. Baseline data were collected prior to the patient deciding on disease management. Main Outcomes and Measures: Baseline patient questionnaires included the Fear of Progression-Short Form and Surgical Fear (referring to thyroidectomy) questionnaires. The fears of women and men were compared after adjustment for age. Decision-related variables, including Decision Self-Efficacy, and the ultimate treatment decisions were also compared between genders. Results: The study included 153 women (mean [SD] age, 50.7 [15.0] years) and 47 men (mean [SD] age, 56.3 [13.8] years). There were no significant differences in primary tumor size, marital status, education, parental status, or employment status between the women and men. After adjustment for age, there was no significant difference observed in the level of fear of disease progression between men and women. However, women reported greater surgical fear compared with men. There was no meaningful difference observed between women and men with respect to decision self-efficacy or the ultimate treatment choice. Conclusions and Relevance: In this cohort study of patients with low-risk PTC, women reported a higher level of surgical fear but not fear of the disease compared with men (after adjustment for age). Women and men were similarly confident and satisfied with their disease management choice. Furthermore, the decisions of women and men were generally not significantly different. The context of gender may contribute to the emotional experience of being diagnosed with thyroid cancer and its treatment perception.

Micro-Ultrasound: Current Role in Prostate Cancer Diagnosis and Future Possibilities.

Prostate Cancer (PCa) is the second most common cancer in men. Population screening using prostate specific antigen (PSA) blood test and digital rectal exam (DRE) is recommended by the NCCN, EAU and other prominent clinical guidelines. While MRI is the recommended initial test in men at risk for PCa, micro-Ultrasound (MicroUS) is a novel high resolution ultrasound technology that has shown promise in PCa detection. This article provides a narrative review of the studies to date which have been conducted to evaluate the functionality and efficacy of MicroUS within the patient care pathway for prostate cancer. A total of 13 relevant publications comparing detection of csPCa between MicroUS and mpMRI were selected. An amount of 4 publications referring to use of MicroUS for other indications were found. Each publication was evaluated for risk of bias and applicability using the Quality Assessment of Diagnostic Accuracy (QUADAS-2) tool. The studies reviewed conclude that MicroUS detection rates for clinically significant prostate cancer diagnosis are comparable to the detection rates of mpMRI guided biopsy procedures. While the existing literature indicates that MicroUS should replace conventional TRUS for prostate imaging and biopsy, it is not yet clear whether MicroUS should be used on its own or in conjunction with mpMRI for augmenting prostate cancer detection. The ongoing OPTIMUM trial will provide evidence on how best to utilize this new technology. Early data also suggest this flexible new imaging modality has a place in local staging and active surveillance of prostate cancer as well as in bladder cancer staging.

The role of [18F]-DCFPyL PET/MRI radiomics for pathological grade group prediction in prostate cancer.

PURPOSE: To evaluate the diagnostic accuracy of [18F]-DCFPyL PET/MRI radiomics for the prediction of pathological grade group in prostate cancer (PCa) in therapy-naïve patients. METHODS: Patients with confirmed or suspected PCa, who underwent [18F]-DCFPyL PET/MRI (n = 105), were included in this retrospective analysis of two prospective clinical trials. Radiomic features were extracted from the segmented volumes following the image biomarker standardization initiative (IBSI) guidelines. Histopathology obtained from systematic and targeted biopsies of the PET/MRI-detected lesions was the reference standard. Histopathology patterns were dichotomized as ISUP GG 1-2 vs. ISUP GG ≥ 3 categories. Different single-modality models were defined for feature extraction, including PET- and MRI-derived radiomic features. The clinical model included age, PSA, and lesions' PROMISE classification. Single models, as well as different combinations of them, were generated to calculate their performances. A cross-validation approach was used to evaluate the internal validity of the models. RESULTS: All radiomic models outperformed the clinical models. The best model for grade group prediction was the combination of PET + ADC + T2w radiomic features, showing sensitivity, specificity, accuracy, and AUC of 0.85, 0.83, 0.84, and 0.85, respectively. The MRI-derived (ADC + T2w) features showed sensitivity, specificity, accuracy, and AUC of 0.88, 0.78, 0.83, and 0.84, respectively. PET-derived features showed 0.83, 0.68, 0.76, and 0.79, respectively. The baseline clinical model showed 0.73, 0.44, 0.60, and 0.58, respectively. The addition of the clinical model to the best radiomic model did not improve the diagnostic performance. The performances of MRI and PET/MRI radiomic models as per the cross-validation scheme yielded an accuracy of 0.80 (AUC = 0.79), whereas clinical models presented an accuracy of 0.60 (AUC = 0.60). CONCLUSION: The combined [18F]-DCFPyL PET/MRI radiomic model was the best-performing model and outperformed the clinical model for pathological grade group prediction, indicating a complementary value of the hybrid PET/MRI model for non-invasive risk stratification of PCa. Further prospective studies are required to confirm the reproducibility and clinical utility of this approach.

PI-RR: The Prostate Imaging for Recurrence Reporting System for MRI Assessment of Local Prostate Cancer Recurrence After Radiation Therapy or Radical Prostatectomy-A Review.

The purpose of this article is to review clinical application of the Prostate Imaging for Recurrence Reporting (PI-RR) system. This system, released in 2021, represents international consensus-based guidelines for the acquisition, interpretation, and reporting of multiparametric MRI performed to detect locally recurrent prostate cancer after radiation therapy or radical prostatectomy. The system reduces variability through use of a standardized and structured reporting approach whereby the overall level of suspicion of recurrence is classified on a 5-point scale. The overall suspicion score is derived from 5-point scales for assessing DWI and dynamic contrast-enhanced (DCE) imaging. Separate scales for both DWI and DCE imaging are provided for evaluation after radiation therapy and after radical prostatectomy. These scales account for the relation between detected abnormalities and the location of the primary tumor on pretreatment imaging. T2-weighted imaging is also assessed on a 5-point scale and is useful for anatomic imaging but does not influence the overall score. Initial retrospective studies have shown promising results with respect to the reproducibility and accuracy of PI-RR in detecting locally recurrent tumor.

Comparison of Micro-US and Multiparametric MRI for Prostate Cancer Detection in Biopsy-Naive Men.

Background Multiparametric MRI has led to increased detection of clinically significant prostate cancer (csPCa). Micro-US is being investigated for csPCa detection. Purpose To compare multiparametric MRI and micro-US in detecting csPCa (grade group ≥2) and to determine the proportion of MRI nodules visible at micro-US for real-time targeted biopsy. Materials and methods This prospective, single-center trial enrolled biopsy-naive men with suspected prostate cancer (PCa) between May 2019 and September 2020. All patients underwent multiparametric MRI followed by micro-US; findings at both were interpreted in a blinded fashion, followed by targeted biopsy and nontargeted systematic biopsy using micro-US. Proportions were compared using the exact McNemar test. The differences in proportions were calculated. Results Ninety-four men (median age, 61 years; IQR, 57-68 years) were included. MRI- and micro-US-targeted biopsy depicted csPCa in 37 (39%) and 33 (35%) of the 94 men, respectively (P = .22); clinically insignificant PCa in 14 (15%) and 15 (16%) (P > .99); and cribriform and/or intraductal PCa in 14 (15%) and 13 (14%) (P > .99). The MRI- plus micro-US-targeted biopsy pathway depicted csPCa in 38 of the 94 (40%) men. The addition of nontargeted systematic biopsy to MRI- plus micro-US-targeted biopsy did not enable identification of any additional men with csPCa but did help identify nine additional men with clinically insignificant PCa (P = .04). Biopsy was avoided in 32 of the 94 men (34%) with MRI and nine of the 94 men (10%) with micro-US (P < .001). Among 93 MRI targets, 62 (67%) were prospectively visible at micro-US. Conclusion MRI and micro-US showed similar rates of prostate cancer detection, but more biopsies were avoided with the MRI pathway than with micro-US, with no benefit of adding nontargeted systematic biopsy to the MRI- plus micro-US-targeted biopsy pathway. Most MRI lesions were prospectively visible at micro-US, allowing real-time targeted biopsy. ClinicalTrials.gov registration no.: NCT03938376 © RSNA, 2022 Online supplemental material is available for this article.

Detection of Clinically Significant Index Prostate Cancer Using Micro-ultrasound: Correlation With Radical Prostatectomy.

OBJECTIVE: To determine the detection of clinically significant prostate cancer (csPCa) index lesion using high resolution transrectal micro-ultrasound (MicroUS) applying PRI-MUS (Prostate Risk Identification using Micro Ultrasound) score v1.0. METHODS: Men who underwent radical prostatectomy following biopsy and MicroUS assessment were included. MicroUS dynamic cine loops of these patients were retrospectively reviewed by an experienced radiologist. The radiologist was aware that patients had undergone radical prostatectomy but was blinded to pathological data. Suspicious sites were assigned a PRI-MUS score. Radical prostatectomy specimens were examined with the quarter mount technique. Detection rate of csPCa index lesion [Grade Group (GG) ≥2] by MicroUS was assessed at a patient level. RESULTS: Twenty-five participants were included in the analysis. The median age was 65.5 years (range 56-74). Median PSA was 6.45 ng/dL (range 2-31.72). Two of 25 patients did not have csPCa (GG1 disease) on radical prostatectomy. MicroUS visualized 20/23 (87%) of the csPCa index lesions [median length 9 mm (range 1.5- 28.5)]. All identified lesions were categorized PRIMUS score 4 or 5. The 3 missed index lesions were in the transition zone [median length 10.5 mm (range 4.5-22.5)]. MicroUS missed 11 non index csPCa in 9 participants [median length 1.5 mm (range 1.5-10.5)]. Of these, 8 were GG2, 2 GG3 and 1 GG5. MicroUS identified the csPCa index lesion in all 9 of these men. CONCLUSION: MicroUS showed the high sensitivity (87%) in detecting index lesions in the prostate gland and identified 100% of index lesions in the peripheral zone.