TABLE 4.

Imaging Findings of Treatment Response, Recurrence, and Toxicities of Various Therapies for Gastroenteropancreatic Neuroendocrine Tumors

Therapy	Treatment Response Pattern	Recurrence	Radiologically Evident Toxicities and Complications
Molecular targeted therapy (sunitinib, everolimus)	Typical: decrease in density and stable to mild decrease in size	Typical: increase in size and density, new separate enhancing masses	Bowel complications (colitis, pneumatosis intestinalis, perforation)
	Atypical: increase in size with decrease in density; increase in size with increase in density; appearance of previously inconspicuous liver lesions (pseudoprogression)	Atypical: new intratumoral nodule or nodules or increased tumor density without necessarily increased size of lesions	Cholecystitis, pancreatitis
			Thromboembolic events
			Noninfectious pneumonitis
Somatostatin analogues (octreotide, lanreotide, pasireotide)	No change in tumor size or morphologic or enhancement pattern	Increase in size	Gallstone and calculous cholecystitis or cholangitis
	Less commonly, mild decrease in size	New separate enhancing masses	Hematoma or abscess in injection sites
Cytotoxic chemotherapy (streptozotocin-based regimen)	Decrease in size of tumors or necrosis	Increase in size	Immunosuppression: opportunistic infection or neutropenic colitis
		New separate enhancing masses	Enterocolitis related to oral administration
Liver-directed therapy (transarterial embolization, ablative therapy, cytoreductive surgery)	Treated portions: complete or partial devascularization	Locally recurrent or residual tumor: solid enhancing intralesional or perilesional nodules or masses	Abscess, cholangitis, cholecystitis, hemorrhage, injury to adjacent organs