MRI accurately determines lesion extent and involvement of surrounding structures, both of which are underestimated clinically in up to 76% of cases [2,5,7]. Contrast-enhanced sequences may not be necessary if typical features, such as flow voids, are present; however, the use of IV contrast is preferred for improved specificity and more complete characterization [3,6,8,20]. IV contrast also allows better visualization of the feeding and draining vessels in high-flow lesions, although this is best performed using an MRA protocol [1-3,6,7,21]. Additionally, MRI is useful for the evaluation of other soft- tissue lesions and musculoskeletal pathologies that might be considered in the differential diagnosis for a mass, enlarged extremity, or pain [19,20,22,23]. MRA Extremity MRA is an excellent imaging option when a vascular malformation is suspected. The typical MRA protocol includes conventional T1 and T2 sequences, which provide anatomic information including lesion size, extent, and internal morphology [6,7]. Dynamic contrast-enhanced MRA, when combined with conventional MRI, has a reported sensitivity of 83% and specificity of 95% for the differentiation of venous and nonvenous malformations [24]. Time-resolved MRA has been shown to be nearly equivalent to arteriography for evaluating dynamic perfusion, allowing for accurate differentiation of feeding arteries and draining veins in high-flow lesions [2,9]. MRA can also be useful in differentiating vascular malformations from other causes of an extremity mass, such as soft-tissue neoplasms, although there may be some overlap in findings [7]. Although noncontrast time-of-flight techniques can be employed, contrast-enhanced MRA is preferred for improved depiction of smaller vessels and dynamic imaging assessment [6,25]. Arteriography Extremity There is no evidence to support the use of arteriography as the initial imaging evaluation for a suspected vascular malformation because of its invasive nature.
Clinically Suspected Vascular Malformation of the Extremities. MRI accurately determines lesion extent and involvement of surrounding structures, both of which are underestimated clinically in up to 76% of cases [2,5,7]. Contrast-enhanced sequences may not be necessary if typical features, such as flow voids, are present; however, the use of IV contrast is preferred for improved specificity and more complete characterization [3,6,8,20]. IV contrast also allows better visualization of the feeding and draining vessels in high-flow lesions, although this is best performed using an MRA protocol [1-3,6,7,21]. Additionally, MRI is useful for the evaluation of other soft- tissue lesions and musculoskeletal pathologies that might be considered in the differential diagnosis for a mass, enlarged extremity, or pain [19,20,22,23]. MRA Extremity MRA is an excellent imaging option when a vascular malformation is suspected. The typical MRA protocol includes conventional T1 and T2 sequences, which provide anatomic information including lesion size, extent, and internal morphology [6,7]. Dynamic contrast-enhanced MRA, when combined with conventional MRI, has a reported sensitivity of 83% and specificity of 95% for the differentiation of venous and nonvenous malformations [24]. Time-resolved MRA has been shown to be nearly equivalent to arteriography for evaluating dynamic perfusion, allowing for accurate differentiation of feeding arteries and draining veins in high-flow lesions [2,9]. MRA can also be useful in differentiating vascular malformations from other causes of an extremity mass, such as soft-tissue neoplasms, although there may be some overlap in findings [7]. Although noncontrast time-of-flight techniques can be employed, contrast-enhanced MRA is preferred for improved depiction of smaller vessels and dynamic imaging assessment [6,25]. Arteriography Extremity There is no evidence to support the use of arteriography as the initial imaging evaluation for a suspected vascular malformation because of its invasive nature.