Atypical MRI features in soft-tissue arteriovenous malformation: a novel imaging appearance with radiologic-pathologic correlation.
BACKGROUND
The absence of a discrete mass, surrounding signal abnormality and solid enhancement are imaging features that have traditionally been used to differentiate soft-tissue arteriovenous malformations from vascular tumors on MRI. We have observed that these findings are not uncommon in arteriovenous malformations, which may lead to misdiagnosis or inappropriate treatment.


OBJECTIVE
To estimate the frequency of atypical MRI features in soft-tissue arteriovenous malformations and assess their relationship to lesion size, location, tissue type involved and vascular architecture.


METHODS
Medical records, MRI and histopathology were reviewed in consecutive patients with soft-tissue arteriovenous malformations in a multidisciplinary vascular anomalies clinic. Arteriovenous malformations were divided into those with and without atypical MRI findings (perilesional T2 signal abnormality, enhancement and/or a soft-tissue mass). Lesion location, size, tissue involved and vascular architecture were also compared between groups. Tissue stains were reviewed in available biopsy or resection specimens to assess relationships between MRI findings and histopathology.


RESULTS
Thirty patients with treatment-naïve arteriovenous malformations were included. Fifteen lesions demonstrated atypical MRI. There was no difference in age, gender, lesion size or involved body part between the groups. However, more than half of the atypical lesions demonstrated multicompartmental involvement, and tiny intralesional flow voids were more common in atypical arteriovenous malformations. Histopathology also differed in atypical cases, showing densely packed endothelial cells with connective tissue architectural distortion and edema.


CONCLUSIONS
Arteriovenous malformations may exhibit features of a vascular tumor on MRI, particularly when multicompartmental and/or containing tiny internal vessels. These features are important to consider in suspected fast-flow vascular malformations and may have implications with respect to their treatment.
Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave., M-361, San Francisco, CA, 94143, USA, anand.patel@ucsf.edu.
Anand S
AS
Patel
Joshua M
JM
Schulman
Beth S
BS
Ruben
William Y
WY
Hoffman
Christopher F
CF
Dowd
Ilona J
IJ
Frieden
Christopher P
CP
Hess
D000293:Adolescent; D000328:Adult; D001165:Arteriovenous Malformations / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003287:Contrast Media; D005260:Female; D005682:Gadolinium; D006801:Humans; D007089:Image Enhancement; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000098:blood supply / Q000473:pathology; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012867:Skin / Q000098:blood supply / Q000473:pathology; D055815:Young Adult
D003287:Contrast Media; D005682:Gadolinium