Local staging of rectal cancer with transrectal ultrasound and endorectal magnetic resonance imaging - Comparison with histologic findings

PURPOSE: The aim of the present study was to compare the accuracy of endore ctal coil magnetic resonance imaging with transrectal ultrasound in staging rectal carcinoma. METHODS: Twenty-six consecutive patients with rectal car cinoma, histologically proven by endoscopic biopsy, were staged with both e ndorectal coil magnetic resonance imaging and transrectal ultrasound and th en underwent radical surgery. The preoperative staging was compared with hi stologic findings of the operative specimen according to TNM classification RESULTS: Endorectal coil magnetic resonance imaging showed better results but was not statistically significantly different from transrectal ultrasou nd in evaluating T (accuracy, 84.6 vs. 76.9 percent): four overstaged and n o understaged cases for the former and five overstaged cases and one unders taged case for the latter. Both procedures showed similar results in evalua ting N: 81 percent sensitivity and 66 percent specificity for endorectal co il magnetic resonance imaging and 72 percent sensitivity and 80 percent spe cificity for transrectal ultrasound. CONCLUSIONS: An accurate locoregional staging of rectal cancer is essential for the planning of optimal therapy f or rectal cancer. Endorectal coil magnetic resonance imaging and transrecta l ultrasound showed similar results; the former is more expensive, whereas the latter is operator dependent. At present the use of endorectal coil mag netic resonance imaging seems to be justified only in selected low rectal c ancers where transrectal ultrasound yielded doubtful results. However, a mo re extensive study is necessary to compare the advantages of these diagnost ic techniques.