Symptomatic peripheral vascular lesions in adults are often clinically diagnosed as
benign vascular anomalies and may receive MRI/MRA for pre-treatment vascular mapping.
Malignant neoplasms are difficult to distinguish from benign vascular anomalies on
MRI/MRA. This study was performed to determine if there are imaging signs that can
distinguish malignancies from benign vascular anomalies in adults imaged with MRI/MRA.
Materials and methods
A radiology database was retrospectively searched for ISSVA classification terms in
MRI/MRA reports from 1/1/2002–1/1/2019. Adult patients (n = 50, 52 corresponding lesions) with contrast-enhanced MRI/MRA, peripheral soft tissue
based lesion (s), and available pathology or long-term (>1 year) imaging follow-up
were included. MRI/MRA images were reviewed by 3 readers for the following lesional
characteristics: morphology (marginal lobulation, internal septations, distinct soft
tissue mass), peri-articular location, T2-weighted characteristics (hyperintensity,
heterogeneity, perilesional edema, and adjacent triangular T2-peaks), bulk fat, hemorrhage,
enhancement pattern (peripheral, diffuse, or absent), neovascularity, low-flow venous
malformation type enhancement, arterial enhancement within 6 s, enhancement curve
(progressive, plateau, or washout), measured size, and multifocality. The MRI/MRA
features' associated sensitivity, specificity, positive predictive value (PPV), and
negative predictive value (NPV) were calculated. To identify factors predictive of
malignancy, a two-stage multivariable analysis was performed.
23% (12/52) of the lesions, corresponding to 22% (11/50) of the patients, were malignant
neoplasms. No single imaging feature reliably predicted malignancy (PPV ≤ 60%). Absence
of distinct soft tissue mass excluded malignancy (NPV 100%). Multivariate analysis
derived a summary score based on the five strongest predictors of malignancy: adjacent
T2 peaks, age ≥ 70 years, distinct soft tissue mass, lesion size ≥ 5 cm, and absence
of septations. A score ≥ 3 resulted in sensitivity of 92% and specificity of 85%.
Extremity MRI/MRA rarely differentiates malignant from benign soft-tissue vascular
tumors in adults. However, MRI/MRA can suggest malignancy when patient age and multiple
imaging features are considered. Periodic clinical follow-up after the planned endovascular
or operative procedure should be performed to avoid missing a malignancy.