Characterization of Clinically Significant Prostate Cancer in the Peripheral Zone Using Rapid B-Insensitive MR Fingerprinting.

Background MR fingerprinting (MRF) has shown utility in focal prostate lesion characterization as a complement to standard prostate MRI. Purpose To determine the utility of a rapid, B-insensitive MRF technique, combined with standard diffusion MRI, in the characterization of focal prostate lesions in the peripheral zone (PZ), with MRI-guided transrectal US fusion biopsy-derived histopathologic analysis as the reference standard. Materials and Methods Between February 2021 and April 2024, consecutive adults with clinical suspicion of prostate cancer (PCa) who had not undergone biopsy underwent MRI, including rapid, B-insensitive MRF (15 seconds per section) on a 3.0-T MRI unit. T1 and T2 from MRF and apparent diffusion coefficient (ADC) from diffusion MRI were assessed as independent variables to differentiate clinically significant PCa (csPCa) from clinically insignificant lesions (CILs) (benign lesions and Gleason score of ≤3 + 3 PCa). Both univariable and multivariable logistic regression analyses with receiver operating characteristic curve analyses were performed to calculate the area under the receiver operating curve (AUC), sensitivity, and specificity. Results Fifty-two males (mean age, 65 years ± 11 [SD]) with 51 PZ lesions (Prostate Imaging Reporting and Data System version 2.1, score ≥3) were included. The mean T2 and ADC were lower for csPCa ( = 22) than for CILs ( = 29) (T2, 56 msec ± 12 vs 80 msec ± 20, respectively [ < .001]; ADC, 668 × 10 mm/sec ± 111 vs 876 × 10 mm/sec ± 181, respectively [ < .001]). At univariable analyses, an optimal T2 cutoff of 58 msec yielded an AUC of 0.87 (95% CI: 0.76, 0.97) (sensitivity, 73% [16 of 22]; specificity, 93% [27 of 29]), whereas an ADC cutoff of 761 × 10 mm/sec yielded an AUC of 0.83 (95% CI: 0.71, 0.95) (sensitivity, 82% [18 of 22]; specificity, 79% [23 of 29]). A multivariable model incorporating both T2 and ADC achieved a higher AUC (AUC, 0.90; 95% CI: 0.81, 1.00; < .001). Further improvement in diagnostic performance was observed when serum prostate-specific antigen density (PSAD) was included (AUC, 0.94; 95% CI: 0.86, 1.0; = .01). Conclusion Rapid, B-insensitive prostate MRF-derived T1 and T2 combined with ADC and serum PSAD improved PCa characterization in the PZ. © RSNA, 2026 See also the editorial by Margolis and Gulani in this issue.