Radiologic spectrum of rectal carcinoid tumors.

Radiographs of 12 carcinoid tumors of the rectum were reviewed and compared with pathologic findings. There was a good correlation between the radiologic and pathologic findings with respect to tumor invasion and extent. Nine tumors that radiologically presented a smooth round defect less than 2.0 cm in diameter did not invade the muscular layer and did not metastasize. Three tumors that presented a deep crater with an irregular edge greater than 2.0 cm were found to have invaded the muscular layer and metastasized to the lymph nodes or the liver. The double-contrast enema showed an excellent detection rate; no lesion was missed by it.