Normalized periprostatic adipose tissue thickness: an imaging marker associated with prostate biopsy outcomes among patients with PI-RADS and PSA double gray zone.

Periprostatic adipose tissue (PPAT) is a potential factor closely associated with prostate cancer (PCa) development. This study aimed to introduce normalized PPAT thickness, a novel imaging biomarker, as a PCa predictor for patients within the diagnostic ‚double gray zone‘, defined as the combination of Prostate Imaging Reporting and Data System (PI-RADS) score 3 lesions and serum prostate-specific antigen (PSA) levels of 4-10 ng/mL. A total of 219 patients were retrospectively enrolled. PPAT thickness was measured on pre-biopsy MRI. Pearson correlation analysis was performed to assess the relationship between BMI and PPAT thickness. Independent predictors of PCa were investigated by logistic regression analysis. Normalized PPAT thickness was defined as the ratio of PPAT thickness to prostate volume, and its predictive performance was compared with PSA density (PSAD). Restricted cubic spline analysis was performed to determine its optimal threshold for PCa prediction. A negative correlation was observed between PPAT thickness and BMI (ρ = -0.154, p = 0.023), suggesting that PPAT is less affected by overall obesity. PPAT thickness was significantly higher in PCa patients (0.52 vs. 0.36 cm, p < 0.001) and was identified as an independent PCa predictor (OR 1.523, 95% CI 1.252-1.853, p < 0.001). Normalized PPAT thickness outperformed PSAD for predicting clinically significant PCa (csPCa) (AUC 0.819 vs. 0.690, p = 0.003), and its threshold of 14 outperformed the traditional PSAD threshold > 0.15 (csPCa detection rate 39.2% vs. 21.7%). In conclusion, we proposed normalized PPAT thickness as a novel PCa predictor in the diagnostically challenging ‚double gray zone‘ cohort.