Search

Background: Image quality evaluation of prostate MRI is important for successful implementation of MRI into localized prostate cancer diagnosis. Purpose: To examine the impact of image quality on prostate cancer detection using an in‐house previously developed artificial intelligence (AI) algorithm. Study Type: Retrospective. Subjects: 615 consecutive patients (median age 67 [interquartile range [IQR]: 61–71] years) with elevated serum PSA (median PSA 6.6 [IQR: 4.6–9.8] ng/mL) prior to prostate biopsy. Field Strength/Sequence: 3.0T/T2‐weighted turbo‐spin‐echo MRI, high b‐value echo‐planar diffusion‐weighted imaging, and gradient recalled echo dynamic contrast‐enhanced. Assessments: Scans were prospectively evaluated during clinical readout using PI‐RADSv2.1 by one genitourinary radiologist with 17 years of experience. For each patient, T2‐weighted images (T2WIs) were classified as high‐quality or low‐quality based on evaluation of both general distortions (eg, motion, distortion, noise, and aliasing) and perceptual distortions (eg, obscured delineation of prostatic capsule, prostatic zones, and excess rectal gas) by a previously developed in‐house AI algorithm. Patients with PI‐RADS category 1 underwent 12‐core ultrasound‐guided systematic biopsy while those with PI‐RADS category 2–5 underwent combined systematic and targeted biopsies. Patient‐level cancer detection rates (CDRs) were calculated for clinically significant prostate cancer (csPCa, International Society of Urological Pathology Grade Group ≥2) by each biopsy method and compared between high‐ and low‐quality images in each PI‐RADS category. Statistical Tests: Fisher's exact test. Bootstrap 95% confidence intervals (CI). A P value <0.05 was considered statistically significant. Results: 385 (63%) T2WIs were classified as high‐quality and 230 (37%) as low‐quality by AI. Targeted biopsy with high‐quality T2WIs resulted in significantly higher clinically significant CDR than low‐quality images for PI‐RADS category 4 lesions (52% [95% CI: 43–61] vs. 32% [95% CI: 22–42]). For combined biopsy, there was no significant difference in patient‐level CDRs for PI‐RADS 4 between high‐ and low‐quality T2WIs (56% [95% CI: 47–64] vs. 44% [95% CI: 34–55]; P = 0.09). Data Conclusion: Higher quality T2WIs were associated with better targeted biopsy clinically significant cancer detection performance for PI‐RADS 4 lesions. Combined biopsy might be needed when T2WI is lower quality. Level of Evidence: 2 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

Objective. Sialic acid-binding immunoglobulin-like lectin 15 (Siglec-15) is overexpressed in various cancers which has led to the development of therapeutic anti-Siglec-15 monoconal antibodies (mAbs). In these preclinical studies, the therapeutic mAb, NC318 (antihuman/murine Siglec-15 mAb), was labeled with zirconium-89 and evaluated in human Siglec-15 expressing cancer cells and mouse xenografts for potential use as a clinical diagnostic imaging agent. Methods. Desferrioxamine-conjugated NC318 was radiolabeled with zirconium-89 to synthesize [89Zr]Zr-DFO-NC318. Cancer cell lines expressing variable Siglec-15 levels were used for in vitro cell binding studies and tumor xenograft mouse models for biodistributions. [89Zr]Zr-DFO-NC318 biodistribution and PET imaging studies to determine tissue uptakes (tissue : muscle ratios, T : M) included pharmacokinetic evaluation in Siglec-15+tumor xenografts and immunocompetent mice, blocking with nonradioactive NC318 (20, 100, and 300 μ g) and xenografts with low/negligible Siglec-15 expressing tumors. Results. [89Zr]Zr-DFO-NC318 exhibited high affinity ( K d ~4 nM) for Siglec-15 and distinguished between moderate and negligible Siglec-15 expression levels in cancer cell lines. The highest [89Zr]Zr-DFO-NC318 uptakes occurred in the spleen and lymph nodes of the Siglec-15+tumor xenografts at all time points followed by Siglec-15+tumor uptake which was lower although highly retained. In immunocompetent mice, the spleen and lymph nodes exhibited lower uptakes indicating that the athymic xenografts had increased Siglec-15+ immune cells. Specific [89Zr]Zr-DFO-NC318 binding to Siglec-15 was proven with NC318 blocking studies in which dose-dependent decreases in Siglec-15+tumor T : Ms were observed. Higher than expected, tumor T : Ms were seen in lower expressing tumors likely due to the contribution of murine Siglec-15+ immune cells in the tumor microenvironment as confirmed by immunohistochemistry. Siglec-15+tumors were identified on PET images whereas low/negligible expressing tumors showed lower uptakes. Conclusions. In vitro and in vivo [89Zr]Zr-DFO-NC318 uptakes correlated with Siglec-15 expression levels in target tissues. Despite uptake in immune cell subsets in the tumor microenvironment, these results suggest that clinical [89Zr]Zr-DFO-NC318 PET imaging may have value in selecting patients for Siglec-15-targeted therapies. [ABSTRACT FROM AUTHOR]

BACKGROUND. Precise risk stratification through MRI/ultrasound (US) fusion-guided targeted biopsy (TBx) can guide optimal prostate cancer (PCa) management. OBJECTIVE. The purpose of this study was to compare PI-RADS version 2.0 (v2.0) and PI-RADS version 2.1 (v2.1) in terms of the rates of International Society of Urological Pathology (ISUP) grade group (GG) upgrade and downgrade from TBx to radical prostatectomy (RP). METHODS. This study entailed a retrospective post hoc analysis of patients who underwent 3-T prostate MRI at a single institution from May 2015 to March 2023 as part of three prospective clinical trials. Trial participants who underwent MRI followed by MRI/US fusion-guided TBx and RP within a 1-year interval were identified. A single genitourinary radiologist performed clinical interpretations of the MRI examinations using PI-RADS v2.0 from May 2015 to March 2019 and PI-RADS v2.1 from April 2019 to March 2023. Upgrade and downgrade rates from TBx to RP were compared using chi-square tests. Clinically significant cancer was defined as ISUP GG2 or greater. RESULTS. The final analysis included 308 patients (median age, 65 years; median PSA density, 0.16 ng/mL 2 ). The v2.0 group ( n = 177) and v2.1 group ( n = 131) showed no significant difference in terms of upgrade rate (29% vs 22%, respectively; p = .15), downgrade rate (19% vs 21%, p = .76), clinically significant upgrade rate (14% vs 10%, p = .27), or clinically significant downgrade rate (1% vs 1%, p > .99). The upgrade rate and downgrade rate were also not significantly different between the v2.0 and v2.1 groups when stratifying by index lesion PI-RADS category or index lesion zone, as well as when assessed only in patients without a prior PCa diagnosis (all p > .01). Among patients with GG2 or GG3 at RP ( n = 121 for v2.0; n = 103 for v2.1), the concordance rate between TBx and RP was not significantly different between the v2.0 and v2.1 groups (53% vs 57%, p = .51). CONCLUSION. Upgrade and downgrade rates from TBx to RP were not significantly different between patients whose MRI examinations were clinically interpreted using v2.0 or v2.1. CLINICAL IMPACT. Implementation of the most recent PI-RADS update did not improve the incongruence in PCa grade assessment between TBx and surgery.

BACKGROUND. Currently most clinical models for predicting biochemical recurrence (BCR) of prostate cancer (PCa) after radical prostatectomy (RP) incorporate staging information from RP specimens, creating a gap in preoperative risk assessment. OBJECTIVE. The purpose of our study was to compare the utility of presurgical staging information from MRI and postsurgical staging information from RP pathology in predicting BCR in patients with PCa. METHODS. This retrospective study included 604 patients (median age, 60 years) with PCa who underwent prostate MRI before RP from June 2007 to December 2018. A single genitourinary radiologist assessed MRI examinations for extraprostatic extension (EPE) and seminal vesicle invasion (SVI) during clinical interpretations. The utility of EPE and SVI on MRI and RP pathology for BCR prediction was assessed through Kaplan-Meier and Cox proportional hazards analyses. Established clinical BCR prediction models, including the University of California San Francisco Cancer of the Prostate Risk Assessment (UCSF-CAPRA) model and the Cancer of the Prostate Risk Assessment Postsurgical (CAPRA-S) model, were evaluated in a subset of 374 patients with available Gleason grade groups from biopsy and RP pathology; two CAPRA-MRI models (CAPRA-S model with modifications to replace RP pathologic staging features with MRI staging features) were also assessed. RESULTS. Univariable predictors of BCR included EPE on MRI (HR = 3.6), SVI on MRI (HR = 4.4), EPE on RP pathology (HR = 5.0), and SVI on RP pathology (HR = 4.6) (all p < .001). Three-year BCR-free survival (RFS) rates for patients without versus with EPE were 84% versus 59% for MRI and 89% versus 58% for RP pathology, and 3-year RFS rates for patients without versus with SVI were 82% versus 50% for MRI and 83% versus 54% for RP histology (all p < .001). For patients with T3 disease on RP pathology, 3-year RFS rates were 67% and 41% for patients without and with T3 disease on MRI. AUCs of CAPRA models, including CAPRA-MRI models, ranged from 0.743 to 0.778. AUCs were not significantly different between CAPRA-S and CAPRA-MRI models ( p > .05). RFS rates were significantly different between low- and intermediate-risk groups for only CAPRA-MRI models (80% vs 51% and 74% vs 44%; both p < .001). CONCLUSION. Presurgical MRI-based staging features perform comparably to postsurgical pathologic staging features for predicting BCR. CLINICAL IMPACT. MRI staging can preoperatively identify patients at high BCR risk, helping to inform early clinical decision-making. TRIAL REGISTRATION. ClinicalTrials.gov NCT00026884 and NCT02594202.

Indeterminate bone lesions (IBLs) on prostate-specific membrane antigen (PSMA) PET/CT are common. This study aimed to define variables that predict whether such lesions are likely malignant or benign using features on PSMA PET/CT. Methods: 18 F-DCFPyL PET/CT imaging was performed on 243 consecutive patients with high-risk primary or biochemically recurrent prostate cancer. IBLs identified on PSMA PET/CT could not definitively be interpreted as benign or malignant. Medical records of patients with IBLs were reviewed to determine the ultimate status of each lesion. IBLs were deemed malignant or benign on the basis of evidence of progression or stability at follow-up, respectively, or by biopsy results; IBLs were deemed equivocal when insufficient or unclear evidence existed. Post hoc patient, lesion, and scan variables accounting for clustered data were evaluated using Wilcoxon rank-sum and χ 2 tests to determine features that favored benign or malignant interpretation. Results: Overall, 98 IBLs within 267 bone lesions (36.7%) were identified in 48 of 243 patients (19.8%). Thirty-seven of 98 IBLs were deemed benign, and 42 were deemed malignant, of which 8 had histologic verification; 19 remained equivocal. Location and SUV max categorical variables were predictive of IBL interpretation ( P = 0.0201 and P = 0.0230, respectively). For IBLs with new interpretations, 34 of 37 (91.9%) considered benign showed an SUV max of less than 5 or exhibited focal uptake without coexisting bone metastases; 37 of 42 (88.1%) deemed malignant demonstrated an SUV max of at least 5 or were present with coexisting bone metastases. Logistic regression predicted IBLs with a high SUV max (univariable: odds ratio [OR], 9.29 [ P = 0.0016]; multivariable: OR, 13.87 [ P = 0.0089]) or present with other bone metastases (univariable: OR, 9.87 [ P = 0.0112]; multivariable: OR, 11.35 [ P = 0.003]) to be malignant. Conclusion: IBLs on PSMA PET/CT are concerning; however, characterizing their location, SUV, and additional scan findings can aid interpretation. IBLs displaying an SUV max of at least 5 or present with other bone metastases favor malignancy. IBLs without accompanying bone metastases that exhibit an SUV max of less than 5 and are observed only in atypical locations favor benign processes. These guidelines may assist in the interpretation of IBLs on PSMA PET/CT., (© 2023 by the Society of Nuclear Medicine and Molecular Imaging.)

Rhodium-105 (0.567 MeV β - , 319 keV γ, 35.4 h half-life) was produced by neutron irradiation of enriched 104 Ru (>99%) over multiple decades. A method is reported to recover the previously irradiated 104 Ru (trapped in HCl as RuO 4 2- ) as the metal. The 104 Ru was recovered in >93% yield and >98% enrichment. Neutron re-irradiation of the recycled 104 Ru produced 105 Rh, which was successfully radiolabeled with tetrathioethers in high yield. This recovery and recycling method for enriched 104 Ru makes 105 Rh production and utilization economical., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Positron-emitting 72 As is the PET imaging counterpart for beta-emitting 77 As. Its parent, no carrier added (n.c.a.) 72 Se, was produced for a 72 Se/ 72 As generator by irradiating an enriched 7 °Ge metal-graphite target via the 70 Ge(α, 2 n) 72 Se reaction. Target dissolution used a fast, environmentally friendly method with 93% radioactivity recovery. Chromatographic parameters of the 72 Se/ 72 As generator were evaluated, the eluted n.c.a. 72 As was characterized with a phantom imaging study, and the previously reported trithiol and aryl-dithiol ligand systems were radiolabeled with the separated n.c.a. 72 As in high yield., (Copyright © 2018 Elsevier Ltd. All rights reserved.)