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

Abstract

Background.The Restriction Spectrum Imaging restriction score (RSIrs) has demonstrated higher diagnostic accuracy for clinically significant prostate cancer (csPCa) than conventional DWI. Both diffusion andT2properties of prostate tissue inform the RSI signal, and studies have shown that each may be valuable for csPCa discrimination.Purpose.To determine whether prostateT2varies across RSI compartments and in the presence of csPCa, and to evaluate whether consideration of compartmentalT2(cT2) 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. cT2values 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 cT2in combination with RSI measurements.Statistical Tests.Two-sample t-tests (α=0.05) were used to compare cT2values 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,T2differed (p<0.05) across all RSI compartments (C1, C2, C3, C4). Voxel-level data from cohort 1 showed thatT2differed between normal and cancerous tissue in C1, C2, C3(p<0.001). Whole-prostateT2differed between patients with and without csPCa in C3(p=0.02). In cohort 2, whole-prostateT2differed in C1(p=0.01), C3(p=0.01), and C4(p<0.01). Consideration of cT2improved 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 cT2were observed between normal and cancerous prostatic tissue. With our data, however, consideration of cT2did not significantly improve cancer detection performance over RSIrs alone.