Utility of quantitative measurement ofT₂using Restriction Spectrum Imaging for detection of clinically significant prostate cancer

Background The Restriction Spectrum Imaging restriction score (RSIrs) has demonstrated higher diagnostic accuracy for clinically significant prostate cancer (csPCa) than conventional DWI. Both diffusion and T 2 properties of prostate tissue inform the RSI signal, and studies have shown that each may be valuable for csPCa discrimination. Purpose To determine whether prostate T 2 varies across RSI compartments and in the presence of csPCa, and to evaluate whether consideration of compartmental T 2 (c T 2 ) improves csPCa detection over RSIrs alone. Study Type Retrospective. Population Two cohorts (46 and 195 patients) scanned for csPCa. Field Strength/Sequence 3T multi- b -value DWI acquired at multiple TEs. Assessment c T 2 values were computed from multi-TE RSI data and compared between RSI model compartments. csPCa detection was compared between RSIrs and a logistic regression model (LRM) for predicting the probability of csPCa using c T 2 in combination with RSI measurements. Statistical Tests T wo-sample t-tests (α=0.05) were used to compare c T 2 values between compartments and between patients with and without csPCa. Area under the receiver operating characteristic curve (AUC) was used to evaluate csPCa detection performance. Results In both cohorts, T 2 differed ( p <0.05) across all RSI compartments ( C 1, C 2, C 3, C 4 ). Voxel-level data from cohort 1 showed that T 2 differed between normal and cancerous tissue in C 1, C 2, C 3 ( p <0.001). Whole-prostate T 2 differed between patients with and without csPCa in C 3 ( p =0.02). In cohort 2, whole-prostate T 2 differed in C 1 ( p =0.01), C 3 ( p =0.01), and C 4 ( p <0.01). Consideration of c T 2 improved csPCa discrimination compared to diffusion alone, but not compared to RSIrs [cohort 1: 0.80 vs 0.70 (diffusion) and 0.80 (RSIrs), cohort 2: 0.72 vs 0.65 (diffusion) and 0.72 (RSIrs)]. Data Conclusion Significant differences in c T 2 were observed between normal and cancerous prostatic tissue. With our data, however, consideration of c T 2 did not significantly improve cancer detection performance over RSIrs alone.