Preoperative magnetic resonance staging of rectal cancer with an endorectal coil and dynamic gadolinium enhancement

Background: The aim of the study was to assess the value of endorectal coil magnetic resonance imaging (MRI) with gadolinium enhancement in the preoperative staging of rectal cancer. Methods: In addition to standard evaluation, patients with rectal lesions were assessed by MRI obtained with a pelvic phased-array coil in combination with an endorectal coil. Results: The study group comprised 29 patients with rectal cancer staged with an endorectal coil who had surgery without preoperative adjuvant therapy. In addition to standard T-1- and T-2-weighted images, dynamic contrast-enhanced images were acquired in all patients. Considerable interobserver variation was noted, particularly for pathological tumour stage pT(1) or pT(2) (kappa = 0.36). Compared with pathological findings, endorectal MRI correctly staged nine patients, overstaged 16 and understaged four. Whilst lymph node metastases were accurately detected in 70 per cent of patients, the positive predictive value was only 58 per cent. Conclusion: MR staging of rectal cancer with an endorectal coil and gadolinium enhancement is inaccurate for early tumours (stage T-1 or T-2) and is associated with a considerable degree of interobserver variation for individual scan sequences.