Role of magnetic resonance in bowel pathologies: Beyond inflammatory bowel disease

Table 2 Comparative magnetic resonance imaging features of common benign and primary malignant small bowel neoplasms

Category	Lesion	MRI features
Benign	Adenoma	Small, well-defined, intraluminal soft-tissue lesion, usually < 2 cm, with moderate enhancement
	Lipoma	Signal intensity identical to fat, hyperintense on T1 and T2, with signal loss on fat-suppressed sequences
	Hemangioma	T2 hyperintense and enhancing; cavernous subtypes may appear polypoid or submucosal
	Leiomyoma	Well-circumscribed, submucosal smooth-muscle tumor; homogeneous focal mass with uniform enhancement greater than adjacent bowel
Malignant	Adenocarcinoma	Annular or constricting lesion narrowing the lumen, often with irregular wall thickening and obstruction
	Neuroendocrine tumor	Hyperenhancing primary lesion; often isointense to adjacent musculature on T1 and isointense to mildly hyperintense on T2; may be associated with a mesenteric mass or desmoplastic reaction
	GIST	Exophytic, heterogeneously enhancing mass that may demonstrate necrosis or hemorrhage
	Lymphoma	Variable appearance, including long-segment involvement and aneurysmal dilatation; splenomegaly and lymphadenopathy may support the diagnosis

MRI: Magnetic resonance imaging; GIST: Gastrointestinal stromal tumor.