To investigate relaxation along a fictitious field (RAFF) and continuous wave (cw) T_1ρ imaging of prostate cancer (PCa) in the terms of repeatability, PCa detection, and characterization.

Thirty-six patients (PSA 11.6 ± 7.6 ng/mL, mean ± standard deviation) with histologically confirmed PCa underwent two repeated 3T MR examinations using surface array coils before prostatectomy. Relaxation along fictitious field, cw T_1ρ, and T₂ relaxation times (T_RAFF, T_1ρcw, T₂) were measured and averaged over regions of interest placed in PCa, normal peripheral zone (PZ), and normal central gland (CG) positioned using whole-mount prostatectomy sections and anatomical T₂-weighted images. Receiver operating characteristic curve analysis with area under the curve (AUC) was calculated to distinguish PCa from PZ/CG and PCa with Gleason score (GS) of 3+3 from GS of 3+4/≥3+4.

T_RAFF and T_1ρcw relaxation times were repeatable with coefficients of repeatability as a percentage of median value in the range of 7.8–23.2%. AUC (mean, 95% confidence interval) in the differentiation of PCa with GS of 3+3 from PCa with CS of ≥3+4 were 0.88 (0.72–0.99), 0.69 (0.46–0.90), and 0.68 (0.45–0.88), for T_RAFF, T_1ρcw, and T₂, respectively.

In quantitative region of interest based analysis, T_RAFF outperformed T_1ρcw and T₂ in PCa detection and characterization.