Objective: To investigate the value of colonoscopic miniprobe ultrasonography for preoperative staging of colorectal neoplasms.
Summary background data: Endoscopic ultrasonography is the most accurate technique for staging colorectal cancer. However, limitations of this technique include the inability to examine stenotic tumors and the difficulty of reaching tumors proximal to the rectum.
Methods: Miniprobe ultrasonography (12.5 MHz) was performed in 63 patients with tumors of the colon or rectum. The results of imaging were compared with endoscopic assessment of the lesions and histopathologic findings of the resected specimens.
Results: Miniprobe ultrasonography allowed high-resolution imaging of colorectal tumors during routine colonoscopy. The infiltration depth was correctly classified in 22 adenoma, 3 T1, 10 T2, and 22 T3 or T4 tumors. The accuracy for tumors of the rectum and colon was 86% and 92%, respectively (overall accuracy 90%). The small diameter of the probe allowed examination of 21 stenotic tumors with an accuracy of 86%. Miniprobe ultrasonography revealed carcinoma in 5 of 30 broad-based polyps, although adenomas were diagnosed by endoscopy. Correct assessment of lymph node involvement was obtained in 47 of 55 patients. Based on the findings of miniprobe ultrasonography, management was modified in 7 of the 63 patients.
Conclusions: These preliminary results show that miniprobe ultrasonography improves preoperative staging of stenotic rectal cancer and colonic tumors. This technique can be easily performed during routine colonoscopy and may have considerable impact on surgical therapy.