| [ Summary ] |
To evaluate the usefulness of high-frequency ultrasound probes (HFUP) for invasion depth diagnosis of early colorectal cancers, we retrospectively compared the diagnostic accuracy of HFUP, barium enema and colonoscopy. HFUP was conducted in 138 cases but 22 (15.9%) of cases were excluded from the study because we failed to get adequate quantities of images to evaluate, when the lesions existed on or behind the colonic folds, or when the lesions were highly elevated, in which marked deep attenuation of ultrasound was noted. Overall diagnostic accuracy was similar among these modalities ; 81.7% (272/333) through radiography, 88.5% (583/659) through colonoscopy and 77.6% (90/116) through HFUP. However, HFUP showed higher diagnostic accuracy than barium enema or colonoscopy in case of cancers with moderate to massive submucosal invasion (sm2-3). On the other hand, lower diagnostic accuracy was noticed in HFUP than in other cases such as intramucosal and focally invasive submucosal cancers (m-sm1). Over diagnosis of HFUP was found in 21 cases, caused by ultrasound attenuation (n=6), submucosal lymphocyte infiltration and/or fibrosis (n=6), thickness of proper muscle layer (n=3), etc. The diagnostic accuracy was not improved in any of the two combinations, but rose when combined with all three modalities. These results indicate that HFUP is a useful tool for invasion depth diagnosis of sm2-3 early nonpolypoid cancers, but is not as important for the diagnosis of polypoid cancers. |