Magnetic resonance imaging findings of vascular malformations of the lowerextremity

Vascular malformations are congenital lesions resulting from a defect durin g embryogenesis. Magnetic resonance imaging (MRI) is a very effective metho d for demonstrating detailed information regarding involved structures, ext ent, and flow characteristics of vascular malformations. In previous MRI st udies, most of the emphasis is laid on the difference between high- and low -flow lesions, whereas little detailed information is available about the e xtent of local tissue involvement. These additional characteristics may inf luence the approach in treating these malformations and improve understandi ng of the pathogenesis. We retrospectively reviewed MRI scans of 40 patient s with vascular malformations of the lower extremity. Thirty-four patients had low-flow lesions, and six had high-flow lesions. Of the low-flow lesion s, 23 patients (67.6 percent) had muscle infiltration, with four of the six high-flow lesions having muscle infiltration. Nine of the I I male patient s (81.8 percent) with low-flow lesions had associated muscle infiltration, in comparison with 14 of the 23 female patients (60.9 percent) with low-flo w lesions (p = 0.206). Eighty percent of the vascular malformations located on the thigh with muscle involvement had involvement of the anterior muscl e group, whereas 86.6 percent of the patients with a vascular malformation located on the leg and with associated muscle involvement had at least the posterior muscle group involved (p = 0.0049). Ten patients (25 percent) of the whole group had bone infiltration. Low-flow lesions often had multifoca l lesions (20.6 percent), whereas associated muscle atrophy was visible in 10 low-flow lesions and in two high-flow lesions. In low-flow lesions with muscle infiltration (n = 23), 43 percent (n = 10) had associated surroundin g muscle atrophy (p = 0.009). Hypertrophy of the subcutaneous tissue was vi sible in 11 low-flow patients (32.4 percent). The high amount of muscle and bone involvement in vascular malformations of the lower extremity is empha sized with this study. Of particular interest was the difference in affecte d muscle groups. The angiosome concept is used to explain this preponderanc e, and we feel the angiosome concept could also be used when assessing poss ible intervention. The surrounding muscle atrophy and multifocal nature of these anomalies are further important considerations when assessing the pos sibility of intervention.