Comparison of Reduced FOV Diffusion-weighted Imaging of Rectal Cancer at 5.0T ultra- high field versus 3.0T MRI: Image Quality and Histopathological T Staging

Purpose To compare image quality (IQ) of reduced field-of-view (rFOV) DWI for rectal cancer at 5.0 T compared with 3.0T and determine whether tumor ADC values are correlated with histopathological T staging. Materials and Methods In a prospective cohort, 36 patients diagnosed with rectal cancer underwent MRI scans on both 3.0T and 5.0T systems. Two experienced radiologists separately evaluated the subjective and objective IQ parameters. Objective IQ metrics were statistically analyzed utilizing paired t-tests. Subjective assessments were compared utilizing the Wilcoxon signed-rank test. Tumor ADC values obtained at the two magnetic field strengths were further compared, and their association with histopathological T stage was examined through Spearman’s rank correlation. Results Objective measures demonstrated evidently improved IQ on 5.0T rFOV DWI relative to 3.0T (all P  < 0.001). Subjective evaluations confirmed superior image clarity, lesion delineation, and overall diagnostic confidence on the 5.0T platform ( P  < 0.001). The two systems demonstrated comparable performance with respect to image artifacts and geometric distortions, showing no meaningful statistical divergence. However, the mean tumor ADC values differed significantly between 3.0T and 5.0T imaging ( P  < 0.001). A notable inverse correlation was identified between ADC values and histopathological T stage at both field strengths ( P  < 0.001). Conclusion rFOV DWI at 5.0T offers enhanced IQ and improved tumor visualization relative to 3.0T. The mean tumor ADC values were significantly different at 3.0T and 5.0T, which could be utilized for assessing histopathological T staging of rectal cancer.