Abstract
BACKGROUND: Systematic MRI findings of solitary rectal ulcer syndrome (SRUS) are lacking. We aimed to evaluate the MRI findings of SRUS and to identify the MRI features that differentiate SRUS from rectal cancer. METHODS: This retrospective study consecutively included 30 patients diagnosed with SRUS from January 2015 to December 2021. The clinical and MRI findings of SRUS patients were summarized. We randomly selected 120 rectal cancer patients with ≤ T2N0 pathological staging in a 1:4 ratio of SRUS to rectal cancer cases to perform differential diagnosis analysis. RESULTS: SRUS patients were significantly younger (mean age ± standard deviation [SD], 37 years ± 17; 22 men) than rectal cancer patients (mean age ± SD, 62 years ± 12; 67 men; p < 0.001). Compared to rectal cancer patients, SRUS patients had a significantly higher incidence of ulceration (63.33%), submucosal edema (36.67%), unrestricted diffusion (76.67%), hypo- or high-low mixed intensity on T2-weighted imaging (T2WI, 76.67%), and layer enhancement (40%) (all p < 0.001). Interestingly, in the combinations of MRI features including unrestricted diffusion, hypo- or high-low mixed intensity on T2WI, and layer enhancement or submucosal edema showed an excellent diagnostic performance with area under the curve, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 0.97 (95% CI: 0.92, 1.00), 93%, 100%, 100%, 98%, and 99%, respectively, in differentiating SRUS from rectal cancer. CONCLUSION: The combinations of three MRI features are simple and show excellent diagnostic performance. These may be useful tools for differentiating SRUS from rectal cancer. CRITICAL RELEVANCE STATEMENT: The combinations of three MRI features including unrestricted diffusion, hypo- or high-low mixed intensity on T2WI, and layer enhancement or submucosal edema show excellent diagnostic performance, which have potential to serve as useful tools for differentiating SRUS from rectal cancer. KEY POINTS: MRI could differentiate solitary rectal ulcer syndrome (SRUS) from rectal cancer. SRUS patients had a significantly higher incidence of several MRI features. The combinations have potential for differentiating SRUS from rectal cancer.