Vascular malformations in the extremities: emphasis on MR imaging features that guide treatment options.

Vascular malformations can be classified into high-flow arteriovenous malformations (AVM) and low-flow venous or lymphatic malformations (VM/LM). VMs and LMs have the ability to cross multiple tissue boundaries. Not only is subcutaneous tissue often involved, but multiple muscle groups, tendons, bone cortex and bone marrow are also not uncommonly violated. Magnetic resonance imaging (MRI) provides valuable information for the assessment and treatment of malformations. Firstly, MRI can characterize the flow pattern of these malformations to guide treatment towards trans-arterial embolization for AVMs and percutaneous embolization for low flow malformations. MRI is essential to define the anatomic extent and involvement of various tissue layers (a distinct advantage over ultrasound), and to correlate treatable components of the malformation with patient symptoms. Treatment is decided by the need to alleviate clinical symptoms, and is dependent on the extent of the malformation as defined by MRI. We present MRI features of vascular malformations to demonstrate the potential spectrum of involvement of these lesions, illustrating the value of MRI in treatment planning.