Image Quality Assessment of Reduced Field-of-View DWI in Rectal Cancer and Its Role in Preoperative T Staging

Abstract

Objective: To construct reduced field-of-view diffusion-weighted imaging (rFOV DWI) based on a 3.0T MRI system and evaluate its technical advantages in rectal cancer imaging, as well as its diagnostic value for preoperative T staging, through comparative analysis of image quality with conventional field-of-view DWI (cFOV DWI). Materials and Methods: Forty-seven patients with pathologically confirmed rectal adenocarcinoma were prospectively enrolled from March 2023 to December 2024, with 30 cases selected for image quality comparison. This study was approved by the Institutional Review Board. All patients underwent preoperative MRI examinations, including both cFOV DWI and rFOV DWI. A paired study design was employed to analyze the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the two DWI sequences. Subjective image quality scoring (5-point scale) was performed using a double-blind method. Paired t-tests were used to compare objective parameters, while Wilcoxon signed-rank tests were applied for subjective scoring differences and ADC value comparisons between the two sequences. Postoperative pathological T staging served as the gold standard, and the diagnostic accuracy of rFOV DWI was evaluated using Kappa consistency analysis. Results: rFOV DWI demonstrated significantly higher objective image quality metrics compared to cFOV DWI (SNR: 139.86 ± 41.54 vs. 156.36 ± 35.94; CNR: 1.87 ± 0.43 vs. 2.24 ± 0.45, P < 0.001). Subjective image quality scores for rFOV DWI were also significantly superior (P < 0.001), indicating higher resolution, reduced distortion, and clearer lesion visualization. Preoperative T staging using rFOV DWI showed good consistency with pathological results (Kappa = 0.650, P < 0.05). Conclusion: The rFOV DWI technique significantly improves MRI image quality in rectal cancer by optimizing the scanning field of view. Its preoperative T staging demonstrates strong agreement with pathological outcomes, highlighting its critical clinical value.