Value of dynamic contrast-enhanced MRI in the diagnosis of acute radiation-induced rectal injury in patients with rectal cancer: A comparison with endoscopy

Objectives

To investigate the diagnostic value of dynamic contrast-enhanced MRI (DCE-MRI) quantitative parameters in acute radiation-induced rectal injury (RRI) among patients with rectal cancer.

Methods

This retrospective study included patients confirmed to rectal cancer who underwent rectal MRI (including a DCE-MRI sequence) and endoscopy after neoadjuvant chemoradiotherapy from November 2014 to July 2022. The enrolled patients were divided into an acute RRI group and a non-acute RRI group based on Vienna rectoscopy score. Two radiologists independently measured DCE-MRI quantitative parameters (including the forward volume transfer constant [K^trans], rate constant [k_ep], and fractional extravascular extracellular space volume [v_e]) and thickness of rectal wall. Receiver operating characteristic curve analysis was performed to analyze statistically significant parameters.

Results

Forty-nine patients (median age, 58 years; interquartile range, 14 years; 34 men) were enrolled, 28 of whom were in the acute RRI group. K^trans in patients with acute RRI was significantly lower compared to those without acute RRI (0.049 min⁻¹ vs 0.107 min⁻¹; P < 0.001). The area under the receiver operating characteristic curve of K^trans was 0.80. With a K^trans cutoff value of 0.079 min⁻¹, the sensitivity and specificity were 93 % and 67 %, respectively.

Conclusion

K^trans demonstrated moderate performance in diagnosing acute RRI, providing a non-invasive and objective basis for managing and treating rectal cancer patients with acute RRI.