MRI characteristics and classification of peripheral vascular malformations and tumors.

Vascular malformations and tumors comprise a broad spectrum of lesions that can cause significant morbidity and even mortality in children and adults. Classification of vascular malformations into high flow and low flow has significant impact on management since the main treatment of the former is transarterial embolization and the later percutaneous sclerotherapy. Magnetic resonance imaging (MRI) is a noninvasive effective tool for imaging and classification of vascular malformations based on the presence of lobulated masses, signal voids, and hemodynamic flow characteristics. MRI also provides details about anatomic extent of the lesion, proximity to vital structures, and involvement of multiple tissue planes. The prototype of vascular tumors is infantile hemangioma with its typical involution after a proliferative phase during infancy. Hemangioma appears as a distinct intensely enhancing soft tissue mass with enlarged feeding arteries and draining veins. Less common vascular tumors include congenital hemangioma, kaposiform hemangioendothilioma, angiolipoma, angiosarcoma, and hemangiopericytoma.