title: Preoperative embolization of intracranial hemangiopericytomas: case series and introduction of the transtumoral embolization technique.
abstract: OBJECTIVE
  Hemangiopericytomas (HPCs) are rare dural-based neoplasms. Preoperative embolization of these notoriously hypervascular tumors can be challenging as they often receive their dominant blood supply from pial feeders arising from the internal carotid artery (ICA) or vertebrobasilar (VB) circulation. This study reviews our historical experience with HPC embolization and introduces the transtumoral technique for backfilling pial tumor vasculature by delivering Onyx-18 through diminutive external carotid artery (ECA) feeders.
  
  
  METHODS
  A retrospective review of all preoperative HPC embolizations performed at Anonymous University #1 (September 2002-November 2014) and Anonymous University #2 (January 2014-November 2014) is presented.
  
  
  RESULTS
  Fifteen patients with pathologically confirmed HPC underwent 17 embolizations. More extensive devascularization percentages were achieved for HPCs with primarily ECA blood supply (76.4±10.7%; n=6) than with HPCs supplied via the ICA/VB circulation (57.9±26.9%; n=8; p=0.046). There was a trend towards greater devascularization of ICA/VB-dominant HPCs embolized with Onyx (70.0±34.6%; n=4) versus polyvinyl alcohol particles (33.3±15.3%; n=3). The extent of angiographic devascularization negatively correlated with intraoperative blood loss (rho=-0.71; p=0.005). There were no embolization-related complications.
  
  
  CONCLUSIONS
  The extent of preoperative embolization of HPCs correlates with decreased intraoperative blood loss. However, HPCs with an ICA/VB-dominant blood supply remain challenging embolization targets, demonstrating reduced devascularization percentages compared with ECA-dominant counterparts. The authors favor the use of Onyx for ICA/VB-dominant HPCs, noting a trend towards an improved devascularization rate.
authors.affiliation: Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington, USA.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Hanak
authors.affiliation: Department of Neurology, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Diogo C
authors.initials: DC
authors.lastname: Haussen
authors.affiliation: Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA.
authors.forename: Sudheer
authors.initials: S
authors.lastname: Ambekar
authors.affiliation: Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington, USA.
authors.forename: Manuel
authors.initials: M
authors.lastname: Ferreira
authors.affiliation: Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington, USA Department of Neuroradiology, University of Washington School of Medicine, Seattle, Washington, USA.
authors.forename: Basavaraj V
authors.initials: BV
authors.lastname: Ghodke
authors.affiliation: Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Peterson
mesh_terms: D000328:Adult; D000368:Aged; D016063:Blood Loss, Surgical; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000628:therapy*; D002342:Carotid Artery, External / Q000000981:diagnostic imaging; D004338:Drug Combinations; D004621:Embolization, Therapeutic / Q000379:methods*; D057510:Endovascular Procedures / Q000379:methods; D005260:Female; D006393:Hemangiopericytoma / Q000000981:diagnostic imaging / Q000628:therapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011142:Polyvinyl Alcohol; D011145:Polyvinyls; D012189:Retrospective Studies; D015607:Stents; D013635:Tantalum; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D004338:Drug Combinations; C558446:Onyx 18; D011145:Polyvinyls; D013635:Tantalum; D011142:Polyvinyl Alcohol
keywords: Angiography; Liquid Embolic Material; Neoplasm; Technique; Tumor