Dynamic contrast-enhanced MRI: Use in predicting pathological complete response to neoadjuvant chemoradiation in locally advanced rectal cancer.

PURPOSE

To determine the ability of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to predict pathological complete response (pCR) before preoperative chemoradiotherapy (CRT) in locally advanced rectal cancer.

MATERIALS AND METHODS

In a prospective clinical trial, 38 enrolled patients underwent pre- and post-CRT DCE-MRI at 3.0T. The tumor length and the following perfusion parameters (K(trans) , kep , ve ) were measured for the tumor and compared between the pCR group and the non-pCR group, as well as before and after CRT. For categorical variable comparison, the Kruskal-Wallis test was used. P < 0.05 was considered significant.

RESULTS

No difference in tumor length was found between the pCR and non-pCR group pre- and post-CRT (P = 0.26 (0.15,0.45), 0.35 (0.21,0.52), respectively). Before CRT, the mean tumor K(trans) in the pCR group was significantly higher than in the non-pCR group (P = 0.01). A K(trans) of 0.66 emerged as the best cutoff for distinguishing pCR from non-pCR. Regarding kep and ve , significant differences were also observed between the pCR and non-pCR groups (P = 0.02, 0.01, respectively). The mean K(trans) , kep , and ve values post-CRT were lower in the pCR group than in the non-pCR group, although there was no significant difference (P = 0.10 (0.04,0.16), 0.11 (0.07,0.26), 0.10 (0.06,0.23), respectively).

CONCLUSION

Before neoadjuvant chemoradiotherapy in rectal cancer, DCE-MRI can distinguish between complete and incomplete response using a K(trans) threshold of 0.66 with a sensitivity of 100%.