Recurrent rectal cancer: diagnosis with dynamic MR imaging.

Abstract

To evaluate whether dynamic magnetic resonance (MR) imaging can increase the diagnostic accuracy in suspected local recurrence of rectal carcinoma. Eighteen patients (seven men, 11 women, aged 26-78 years) with 19 suspect lesions were examined. T1-weighted (pre- and postcontrast) and T2-weighted spin-echo images were read by three observers. Computed tissue-specific enhancement parameters were obtained and displayed on gray-scale images (pharmacokinetic mapping). Reading of the spin-echo images yielded a sensitivity of 91%-100% (confidence interval, 67%, 100%), a specificity of 29%-43% (12%, 67%), and an accuracy of 71%-75% (48%, 91%). Analysis of the MR data showed greater (P = .0038) and faster (P = .0018) enhancement of malignant lesions (n = 12) compared with benign lesions (n = 7). Pharmacokinetic mapping of dynamic MR imaging data allows in vivo insight into tissue physiopathology, helping differentiate benign from malignant pelvic lesions in rectal cancer.