Comparison of Virtual MR Elastography Based on Intravoxel Incoherent Motion With MR Elastography in the Assessment of Intratumoral Fibrosis in Rectal Cancer

BACKGROUND: Intratumoral fibrosis influences treatment efficacy and prognosis of rectal cancer (RC). The roles of MR elastography (MRE) and Virtual MRE (VMRE) remain unclear in assessing it in RC. PURPOSE: To evaluate MRE for assessing intratumoral fibrosis in RC, identify optimal b-values for VMRE, and compare their diagnostic performance. STUDY TYPE: Prospective cohort. POPULATION: A total of 71 participants with pathologically confirmed RC (47 men; mean age, 62 ± 10 years). FIELD STRENGTH/SEQUENCES: ), and spin-echo MRE. ASSESSMENT: All participants were divided at a 7:3 ratio: subgroup 1 (N = 49) determined the optimal b-value combination and established the empirical relationship between shifted apparent diffusion coefficient (sADC) and VMRE (Vc, Vφ) based on IVIM, with MRE (c, φ) as reference; subgroup 2 (N = 22) validated this relationship. MRE and VMRE evaluated intratumoral fibrosis in 43 surgically diagnosed participants. STATISTICAL TESTS: Receiver operating characteristic (ROC), Pearson correlation, DeLong test. Bonferroni-adjusted p < 0.05 indicated statistical significance. RESULTS: values were 0.792 and 0.784, respectively (Adjusted p > 0.999). No significant differences in AUCs were observed among all parameters (Adjusted p: 0.384 to > 0.999). Sensitivity and specificity ranges of MRE and VMRE were 85.7%-90.5% and 54.5%-68.2%, respectively. DATA CONCLUSIONS: . No significant difference was observed for assessing intratumoral fibrosis between MRE and VMRE. EVIDENCE LEVEL: 2. TECHNICAL EFFICACY: Stage 2.