ENDORECTAL MR-IMAGING AND ULTRASONOGRAPHY OF RECTAL TUMORS - CORRELATION WITH PATHOLOGICAL STAGING

Purpose: To compare the accuracy of high resolution endorectal magneti c resonance imaging (EMRI) and endorectal ultrasound (EUS) in the preo perative diagnostic of rectal tumours. Patients and methods: Twenty-on e patients with known rectal tumours underwent MR imaging with an endo rectal surface coil and EUS. Transversal EMR images were obtained usin g fast T-2-weighted sequences and pre- and postcontrast T-1-weighted i mages. EUS was performed using a 7.0 MHz transducer. Results of both m ethods were compared with specimens from the resected tumours. Results : Rectal wall layers were reliably demonstrated with both methods in a ll patients. EMRI and EUS determined the depth of rectal wall invasion . EMRI and EUS agreed with pathologic findings in 16/21 cases, respect ively. In one case each, both methods understaged one tumour. EMRI ove rstaged an adenoma as a T-2-tumour. In three and four patients, respec tively, no staging was possible due to technical problems. Conclusion: EMRI and EUS show comparable results in the preoperative T-staging of rectal tumours. Both techniques are not suitable for differentiating benign from malignant lymph nodes accurately. While EMRI is expensive and technically demanding, it allows an objective documentation of pat hological findings which is less dependent on the examiner. Two import ant clinical conclusions can be drawn from the good results of T-stagi ng: Adenomas and T-1-tumours can be treated by local excision. In pati ents with advanced tumours (T-3/T-4) a neoadjuvant therapy can be init iated.