Utility of quantitative measurement of T2 using Restriction Spectrum Imaging for detection of clinically significant prostate cancer

BackgroundThe Restriction Spectrum Imaging restriction score (RSIrs) has demonstrated higher diagnostic accuracy for clinically significant prostate cancer (csPCa) than conventional DWI. Both diffusion and T2 properties of prostate tissue inform the RSI signal, and studies have shown that each may be valuable for csPCa discrimination. PurposeTo determine whether prostate T2 varies across RSI compartments and in the presence of csPCa, and to evaluate whether consideration of compartmental T2 (cT2) improves csPCa detection over RSIrs alone. Study TypeRetrospective. PopulationTwo cohorts (46 and 195 patients) scanned for csPCa. Field Strength/Sequence3T multi-b-value DWI acquired at multiple TEs. AssessmentcT2 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 cT2 in combination with RSI measurements. Statistical TestsTwo-sample t-tests (=0.05) were used to compare cT2 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. ResultsIn both cohorts, T2 differed (p<0.05) across all RSI compartments (C1, C2, C3, C4). Voxel-level data from cohort 1 showed that T2 differed between normal and cancerous tissue in C1, C2, C3 (p<0.001). Whole-prostate T2 differed between patients with and without csPCa in C3 (p=0.02). In cohort 2, whole-prostate T2 differed in C1 (p=0.01), C3 (p=0.01), and C4 (p<0.01). Consideration of cT2 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 ConclusionSignificant differences in cT2 were observed between normal and cancerous prostatic tissue. With our data, however, consideration of cT2 did not significantly improve cancer detection performance over RSIrs alone.