Analysis of the Diagnostic Performance of a Simplified Rectal Magnetic Resonance Imaging Protocol in the Evaluation of Rectal Cancer

Abstract Objective: This study aims to evaluate the diagnostic performance of a simplified rectal MRI scanning protocol in the assessment of patients with rectal cancer. Materials and Methods: This retrospective study included patients with newly diagnosed rectal cancer confirmed by pathology who underwent standard rectal MRI scanning. The simplified rectal MRI scanning protocol consisted of the first three sequences of the standard protocol： pelvic sagittal fat-suppressed T2-weighted imaging (T2WI), oblique axial T2WI, and diffusion-weighted imaging (DWI). Four radiologists independently reviewed the images from the simplified and standard rectal MRI scans to assess image quality and observe the primary tumor, extramural invasion, and lymph node metastasis of rectal cancer. Results: A total of 359 patients (198 males and 161 females; mean age = 62.2 ± 6.5 years) were included. 192 patients had extramural invasion, and 146 patients had regional or distant lymph node metastasis. The image quality of the simplified protocol was rated as good or better in 88.3% of cases, which was significantly higher than that of the standard protocol. The T-staging accuracy of the simplified protocol was 97.77%; the sensitivity and specificity for assessing extramural invasion were 97.42% and 92.61%, respectively; and the sensitivity and specificity for detecting lymph node metastasis were 76.47% and 84.20%, respectively. The T-staging accuracy of the standard protocol was 98.89%; the sensitivity and specificity for assessing extramural invasion were 97.39% and 93.64%, respectively; and the sensitivity and specificity for detecting lymph node metastasis were 78.44% and 86.29%, respectively. No statistically significant differences were observed between the two protocols. Conclusion: The simplified rectal MRI scanning protocol demonstrated comparable accuracy in T-staging, as well as sensitivity and specificity in the evaluation of extramural invasion and lymph node metastasis, to the standard rectal MRI scanning protocol. Moreover, the image quality of the simplified protocol is superior to that of the standard protocol. Therefore, the simplified rectal MRI scanning protocol can be used as an alternative to the standard rectal MRI scanning protocol in clinical practice.