Differentiation between recurrent rectal cancer and postoperative fibrosis by proton MR spectroscopy: correlation with pathologic results

초록

Purpose: To know the differences of proton MR spcectroscopic features between recurrent rectal cancer and fibrosis in post-operative period, and to evaluate the possibility to discriminate recurrent rectal cancer from post-operative fibrosis by analysis of proton MR spectra. Method and materials: We evaluated the proton MR spectra from 25 soft tissue masses in prtirectal area that developed in post-operative period after Mile's operation for the resection of rectal cancer. Our series included 11 cases of recurrect rectal cancer and 14 of fibrotic mass. All cases of recurrent rectal cancer and post-operative fibrosis were confirmed by biopsy. We evaluated the spectra with an attention to the differences of pattern of the curved between recurrent rectal cancer and post-operative fibrosis. Results: Proton MR spectra of post-operative fibrosis showed significantly diminished amount of lipids compared with that of recurrent rectal cancer. With a cut-off value of 0.6 for discriminating recurrent rectal cancer from post-operative fibrosis, both the sensitivity and specificity were 100% (11/11, and 14/14). Conclusion: Recurrent rectal cancer and post-operative fibrosis can be distinguished from each other by analysis of proton MR spectroscopic features, and 1H-MRS can be a new method for differential diagnosis between recurrent rectal cancer and post-operative fibrosis.