Multiparametric MRI and 18F-PSMA-1007 PET/CT for the Detection of Clinically Significant Prostate Cancer.

Background Multiparametric MRI (mpMRI) is effective for detecting prostate cancer (PCa); however, there is a high rate of equivocal Prostate Imaging Reporting and Data System (PI-RADS) 3 lesions and false-positive findings. Purpose To investigate whether fluorine 18 (18F) prostate-specific membrane antigen (PSMA) 1007 PET/CT after mpMRI can help detect localized clinically significant PCa (csPCa), particularly for equivocal PI-RADS 3 lesions. Materials and Methods This prospective study included participants with elevated prostate-specific antigen (PSA) levels referred for prostate mpMRI between September 2020 and February 2022. 18F-PSMA-1007 PET/CT was performed within 30 days of mpMRI and before biopsy. PI-RADS category and level of suspicion (LOS) were assessed. PI-RADS 3 or higher lesions at mpMRI and/or LOS 3 or higher lesions at 18F-PSMA-1007 PET/CT underwent targeted biopsies. PI-RADS 2 or lower and LOS 2 or lower lesions were considered nonsuspicious and were monitored during a 1-year follow-up by means of PSA testing. Diagnostic accuracy was assessed, with histologic examination serving as the reference standard. International Society of Urological Pathology (ISUP) grade 2 or higher was considered csPCa. Results Seventy-five participants (median age, 67 years [range, 52-77 years]) were assessed, with PI-RADS 1 or 2, PI-RADS 3, and PI-RADS 4 or 5 groups each including 25 participants. A total of 102 lesions were identified, of which 80 were PI-RADS 3 or higher and/or LOS 3 or higher and therefore underwent targeted biopsy. The per-participant sensitivity for the detection of csPCa was 95% and 91% for mpMRI and 18F-PSMA-1007 PET/CT, respectively, with respective specificities of 45% and 62%. 18F-PSMA-1007 PET/CT was used to correctly differentiate 17 of 26 PI-RADS 3 lesions (65%), with a negative and positive predictive value of 93% and 27%, respectively, for ruling out or detecting csPCa. One additional significant and one insignificant PCa lesion (PI-RADS 1 or 2) were found at 18F-PSMA-1007 PET/CT that otherwise would have remained undetected. Two participants had ISUP 2 tumors without PSMA uptake that were missed at PET/CT. Conclusion 18F-PSMA-1007 PET/CT showed good sensitivity and moderate specificity for the detection of csPCa and ruled this out in 93% of participants with PI-RADS 3 lesions. Clinical trial registration no. NCT04487847 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Turkbey in this issue.

Implications of the European Association of Urology Recommended Risk Assessment Algorithm for Early Prostate Cancer Detection.

The 2021 European Association of Urology recommendations for early prostate cancer detection included a risk-based algorithm. Risk assessment methods are proposed to prevent excessive use of prostate magnetic resonance imaging (MRI) and biopsy, simultaneously reducing overdiagnosis and overtreatment. However, the clinical implications of sequential use of risk assessment tests have not yet been properly assessed. We provide an appraisal of the recommended algorithm and evaluate its outcomes in a contemporary prospective study population of biopsy-naïve men. To increase the effectiveness in cases of limited MRI capacity, we show that use of the Rotterdam Prostate Cancer Risk Calculator-3 for pre-MRI risk stratification could avoid more than one-third of MRI examinations. After prostate MRI, use of either the Prostate Imaging-Reporting and Data System (PI-RADS) score or a risk model including MRI outcome as a variable could avoid six out of ten prostate biopsies while maintaining high sensitivity. However, implementation in health care systems requires due consideration of the access to and quality of diagnostic resources, as well as cost-effectiveness. Patient summary: We evaluated the European Association of Urology risk-based strategy for early prostate cancer detection. Risk assessment before magnetic resonance imaging (MRI) using a risk calculator or prostate-specific antigen (PSA) density could reduce MRI demands and overdiagnosis of insignificant cancers. Risk assessment using prostate MRI results could avoid 60% of prostate biopsies while maintaining prostate cancer detection rates.The European Association of Urology (EAU) recently published its current position and recommendations on prostate-specific antigen (PSA) testing [1]. On the basis of the literature and expert opinion, a risk-based algorithm for early detection of prostate cancer (PCa) was proposed. The guideline recommends stratifying men with PSA ≥3 ng/ml as either "low risk", for whom magnetic resonance imaging (MRI) can be avoided, or "intermediate and high risk", for whom prostate MRI should be performed as a basis for further diagnostic decisions. Strategies must be developed to use health care resources efficiently and to reduce unnecessary morbidity, anxiety, and costs of diagnostics. However, any paradigm shift inevitably leads to a paucity of research data. As a result, there is still debate regarding which men can safely avoid an initial MRI but are subjected to clinical follow-up, and which men must undergo an immediate MRI. The authors proposed four methods for risk assessment: (1) family history; (2) PSA velocity; (3) PSA density; and (4) risk calculators. It must be stressed that the availability and quality of prostate MRI in each situation should be considered when using these pre-MRI risk assessment tools. We discuss in brief the proposed risk assessment methods including MRI and assess potential outcomes in a contemporary population.

Clinical use of the SelectMDx urinary-biomarker test with or without mpMRI in prostate cancer diagnosis: a prospective, multicenter study in biopsy-naïve men.

BACKGROUND: Risk stratification in men with suspicion of prostate cancer (PCa) requires reliable diagnostic tests, not only to identify high-grade PCa, also to minimize the overdetection of low-grade PCa, and reduction of "unnecessary" prostate MRIs and biopsies. This study aimed to evaluate the SelectMDx test to detect high-grade PCa in biopsy-naïve men. Subsequently, to assess combinations of SelectMDx test and multi-parametric (mp) MRI and its potential impact on patient selection for prostate biopsy. METHODS: This prospective multicenter diagnostic study included 599 biopsy-naïve patients with prostate-specific antigen level ≥3 ng/ml. All patients underwent a SelectMDx test and mpMRI before systematic transrectal ultrasound-guided biopsy (TRUSGB). Patients with a suspicious mpMRI also had an in-bore MR-guided biopsy (MRGB). Histopathologic outcome of TRUSGB and MRGB was used as reference standard. High-grade PCa was defined as ISUP Grade Group (GG) ≥ 2. The primary outcome was the detection rates of low- and high-grade PCa and number of biopsies avoided in four strategies, i.e., (1) SelectMDx test-only, (2) mpMRI-only, (3) SelectMDx test followed by mpMRI when SelectMDx test was positive (conditional strategy), and (4) SelectMDx test and mpMRI in all (joint strategy). A positive SelectMDx test outcome was a risk score of ≥-2.8. Decision curve analysis (DCA) was performed to assess clinical utility. RESULTS: Prevalence of high-grade PCa was 31% (183/599). Thirty-eight percent (227/599) of patients had negative SelectMDx test in whom biopsy could be avoided. Low-grade PCa was not detected in 35% (48/138) with missing 10% (18/183) high-grade PCa. Yet, mpMRI-only could avoid 49% of biopsies, not detecting 4.9% (9/183) of high-grade PCa. The conditional strategy reduces the number of mpMRIs by 38% (227/599), avoiding biopsy in 60% (357/599) and missing 13% (24/183) high-grade PCa. Low-grade PCa was not detected in 58% (80/138). DCA showed the highest net benefit for the mpMRI-only strategy, followed by the conditional strategy at-risk thresholds >10%. CONCLUSIONS: SelectMDx test as a risk stratification tool for biopsy-naïve men avoids unnecessary biopsies in 38%, minimizes low-grade PCa detection, and misses only 10% high-grade PCa. Yet, using mpMRI in all patients had the highest net benefit, avoiding biopsy in 49% and missing 4.9% of high-risk PCa. However, if mpMRI availability is limited or expensive, using mpMRI-only in SelectMDx test positive patients is a good alternative strategy.

Magnetic resonance imaging at ultra-high magnetic field strength: An in vivo assessment of number, size and distribution of pelvic lymph nodes.

OBJECTIVE: The definition of an in vivo nodal anatomical baseline is crucial for validation of representative lymph node dissections and accompanying pathology reports of pelvic cancers, as well as for assessing a potential therapeutic effect of extended lymph node dissections. Therefore the number, size and distribution of lymph nodes in the pelvis were assessed with high-resolution, large field-of-view, 7 Tesla (T) magnetic resonance imaging (MRI) with frequency-selective excitation. MATERIALS AND METHODS: We used 7 T MRI for homogeneous pelvic imaging in 11 young healthy volunteers. Frequency-selective imaging of water and lipids was performed to detect nodal structures in the pelvis. Number and size of detected nodes was measured and size distribution per region was assessed. An average volunteer-normalized nodal size distribution was determined. RESULTS: In total, 564 lymph nodes were detected in six pelvic regions. Mean number was 51.3 with a wide range of 19-91 lymph nodes per volunteer. Mean diameter was 2.3 mm with a range of 1 to 7 mm. 69% Was 2 mm or smaller. The overall size distribution was very similar to the average volunteer-normalized nodal size distribution. CONCLUSIONS: The amount of in vivo visible lymph nodes varies largely between subjects, whereas the normalized size distribution of nodes does not. The presence of many small lymph nodes (≤2mm) renders representative or complete removal of pelvic lymph nodes to be very difficult. 7T MRI may shift the in vivo detection limits of lymph node metastases in the future.

A urinary biomarker-based risk score correlates with multiparametric MRI for prostate cancer detection.

BACKGROUND: Prostate cancer (PCa) diagnostics would greatly benefit from more accurate, non-invasive techniques for the detection of clinically significant disease, leading to a reduction of over-diagnosis and over-treatment. The aim of this study was to determine the association between a novel urinary biomarker-based risk score (SelectMDx), multiparametric MRI (mpMRI) outcomes, and biopsy results for PCa detection. METHODS: This retrospective observational study used data from the validation study of the SelectMDx score, in which urine was collected after digital rectal examination from men undergoing prostate biopsies. A subset of these patients also underwent a mpMRI scan of the prostate. The indications for performing mpMRI were based on persistent clinical suspicion of PCa or local staging after PCa was found upon biopsy. All mpMRI images were centrally reviewed in 2016 by an experienced radiologist blinded for the urine test results and biopsy outcome. The PI-RADS version 2 was used. RESULTS: In total, 172 patients were included for analysis. Hundred (58%) patients had PCa detected upon prostate biopsy, of which 52 (52%) had high-grade disease correlated with a significantly higher SelectMDx score (P < 0.01). The median SelectMDx score was significantly higher in patients with a suspicious significant lesion on mpMRI compared to no suspicion of significant PCa (P < 0.01). For the prediction of mpMRI outcome, the area-under-the-curve of SelectMDx was 0.83 compared to 0.66 for PSA and 0.65 for PCA3. There was a positive association between SelectMDx score and the final PI-RADS grade. There was a statistically significant difference in SelectMDx score between PI-RADS 3 and 4 (P < 0.01) and between PI-RADS 4 and 5 (P < 0.01). CONCLUSIONS: The novel urinary biomarker-based SelectMDx score is a promising tool in PCa detection. This study showed promising results regarding the correlation between the SelectMDx score and mpMRI outcomes, outperforming PCA3. Our results suggest that this risk score could guide clinicians in identifying patients at risk for significant PCa and selecting patients for further radiological diagnostics to reduce unnecessary procedures.

Visibility of prostate cancer on transrectal ultrasound during fusion with multiparametric magnetic resonance imaging for biopsy.

OBJECTIVES: To determine transrectal ultrasound (TRUS) visibility of magnetic resonance (MR) lesions. METHODS: Data from 34 patients with 56 MR lesions and prostatectomy were used. Five observers localized and determined TRUS visibility during retrospective fusion. Visibility was correlated to Prostate Imaging-Reporting and Data System (PIRADS) and Gleason scores. RESULTS: TRUS visibility occurred in 43% of all MR lesions and in 62% of PIRADS 5 lesions. Visible lesions had a significantly lower localization variability. On prostatectomy, 58% of the TRUS-visible lesions had a Gleason 4 or 5 component. CONCLUSIONS: Almost half of the MR lesions were visible on TRUS. TRUS-visible lesions were more aggressive than TRUS-invisible lesions.