title: Hemangiomas and vascular malformations of the head and neck: MR characterization.
abstract: OBJECTIVE
  To characterize the MR appearance of the common hemangioma of infancy as well as low- and high-flow vascular malformations of the head and neck.
  
  
  METHODS
  Twenty patients with vascular lesions of the head and neck proved either by pathology, angiography, and/or unequivocal clinical diagnosis were included. Vascular lesions included 15 low-flow lesions (four hemangiomas, 10 venous malformations, one lymphatic malformation), and five high-flow lesions (three arteriovenous malformations (AVMs) and two invasive combined malformations). All patients had MR studies (generally 1.5 T using routine T1- and T2-weighted spin-echo sequences). Nine had postgadolinium, gradient recalled-echo, CT, and/or angiographic studies.
  
  
  RESULTS
  Deep hemangiomas and venous malformations demonstrate intermediate signal in T1-weighted images, heterogeneous high signal on T2-weighted images, and prominent enhancement. Involuting hemangiomas show focal areas of high signal intensity on T1-weighted images due to fatty replacement. Venous malformations may demonstrate venous lakes seen as homogeneous regions of high signal intensity on T2-weighted images and phleboliths seen as low signal foci. The one patient with lymphatic malformation showed a large multicystic submandibular mass with large hemorrhage-fluid levels. Features of high-flow lesions (AVMs) include serpiginous signal voids, absence of a dominant mass, and intraosseous extension with decreased marrow signal on T1-weighted images. Invasive combined vascular malformations showed serpiginous flow voids and infiltrative solid masses. Low-flow lesions (hemangiomas, venous, and lymphatic malformations) demonstrate distinct MR findings allowing their differentiation from high-flow lesions (AVMs). Deep hemangiomas and venous malformations appear as solid masses and may look identical. Venous lakes and phleboliths are features of venous malformations which, when present, may help in diagnosis. Combined vascular malformations share features of both low- and high-flow malformations.
  
  
  CONCLUSIONS
  MR is useful in delineating the extent of disease and differentiating low- and high-flow vascular lesions.
authors.affiliation: Department of Radiology, University of California, San Francisco 94143-0628.
authors.forename: L L
authors.initials: LL
authors.lastname: Baker
authors.forename: W P
authors.initials: WP
authors.lastname: Dillon
authors.forename: G B
authors.initials: GB
authors.lastname: Hieshima
authors.forename: C F
authors.initials: CF
authors.lastname: Dowd
authors.forename: I J
authors.initials: IJ
authors.lastname: Frieden
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001165:Arteriovenous Malformations / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006257:Head / Q000473:pathology; D006258:Head and Neck Neoplasms / Q000175:diagnosis*; D006391:Hemangioma / Q000175:diagnosis*; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000473:pathology