Carcinoid tumors: imaging procedures and interventional radiology.

The hypervascular nature of carcinoid tumors and their metastases allows a more aggressive role by the radiologist in diagnosis and interventional management. Double-contrast gastrointestinal studies still best define the primary neoplasms. Appendiceal tumors, the most frequent site of carcinoids, frequently escape radiologic detection until large enough to be discovered by computed tomography (CT). Superior mesenteric arteriography of the small bowel and cecum is useful when the scanning procedures are not revealing. The "spokewheel" configuration of the desmoplastic mesenteric masses and lymph node metastases are best seen by CT, whereas hepatic metastases can be demonstrated by CT, CT-angioportography (CTAP), ultrasonography (US), magnetic resonance imaging (MRI), and octreotide scintigraphy. Percutaneous needle biopsy with radiologic guidance confirms the diagnosis of carcinoid tumors and their metastases. Hepatic arteriography is frequently performed in preparation for hepatic embolization or chemoembolization. Hepatic vascular occlusion therapy, the procedure of choice for the management of inoperable carcinoid liver metastases, results in a partial response in at least 50% of patients and a mortality rate of 5%. Chemoembolization with microencapsulated cytotoxic agents and direct percutaneous ethanol injection should also be considered for the treatment of liver metastases.