EUS DIAGNOSIS OF CANCER INFILTRATION IN EARLY COLORECTAL CANCER

Abstract

Endoscopic ultrasonography (EUS) has been used for the diagnosis of cancer infiltration in early colorectal cancer, however, diagnostic criteria varies among institutes. Considering that the shape of the submucosa varies by lesions and that the recognition of muscularis mucosae is still difficult by EUS, diagnosis should be made based on the patterns of EUS images determined by the shape and the infiltration depth. Miniature ultrasonic probes are more suited for the diagnosis of early cancers compared with echocolonoscopes since the visualization of lesion is easier with the former instrument. EUS is more suited for the evaluation of superficial type lesions than elevated ones. The diagnosis by EUS is superior to that of ordinary colonoscopy when a lesion is properly visualized by EUS ; the combination of both modalities is expected to improve the diagnostic accuracy. The causes of incorrect diagnoses in EUS include insufficient visualization of lesions and the presence of inflammatory cell infiltration and/or fibrosis. By analyzing the features of the hypoechoic area in the third layer, the estimation of histology may be possible. EUS is never essential for diagnosing the depth of cancer infiltration in early colorectal cancer ; however, it is considered beneficial since quite different information can be obtained by this modality.