Preoperative Staging of Rectal Tumors: Comparison of Endorectal Ultrasound, Hydro-CT, and High-Resolution Endorectal MRI

Abstract

Aim: The aim of this study was to compare transrectal ultra-sound (TRUS), hydro-computed tomography (hydro-CT), and endorectal magnetic resonance imaging (MRI) in the preoperative staging of rectal cancer. Patients and Methods: 23 patients with rectal adenocarcinoma underwent TRUS, hydro-CT, and MRI (1 Tesla) with endorectal coil. The results were correlated with the histopathological findings based on the TNM classification. Results: T staging with TRUS, hydro-CT, and endorectal MRI correlated with the histopa-thological findings in 83% of patients (19/23). Tumors were overestimated by TRUS in 2/23 patients, by CT in 3/23, and by MRI in 3/23 patients. Tumor size was underestimated by TRUS in 2 patients, by CT and MRI in 1 case each. Local lymphatic node involvement was correctly diagnosed with CT and MRI in 87% and 83%, respectively. Using TRUS, false-negative results in the staging of lymph node involvement were seen in 3/23 patients, whereas 1 patient was over-staged. Using hydro-CT as well as endorectal MRI, overstaging of the local lymph nodes took place in 2/23 patients. Conclusion: All methods are limited because peritumoral inflammation cannot be precisely distinguished from infiltration by the tumor. Correct lymph node staging is hampered in advanced disease using TRUS. In these patients, further cross-sectional imaging may be required.