Usefulness and limitation of computed tomography in the diagnosis of rectal cancer

Computed tomography (CT) was useful to evaluate the rectal cancer about not only the diagnosis of extracanal invasion to other organs and/or the pelvic wall, but also the diagnosis of its recurrence and pelvic lymph nodes metastases. Cancerous lesions were easily recognized as the localized thickness of the rectal wall when air was injected into the rectal lumen. But the screening and the differential diagnosis of rectal abnormalities with CT were limited, because rectal mucosal pattern can not be imaged in detail. So, CT should be carried out after the differential diagnosis and the location of rectal abnormalites can be obtained by the barium enema or the endoscopy.