title: Perfusion CT scanning and CT angiography in the evaluation of extracranial-intracranial bypass grafts.
abstract: OBJECTIVE
  Extracranial-intracranial (EC-IC) bypass surgery remains an important treatment alternative for patients with occlusive cerebrovascular disease. The aim of the present study was to use perfusion CT and CT angiography (CTA) to evaluate cerebral hemodynamics and bypass patency in patients with occlusive cerebrovascular disease before and after EC-IC bypass surgery.
  
  
  METHODS
  Ten patients underwent perfusion CT and CTA before and after bypass surgery. Preoperative and postoperative digital subtraction angiography served as the diagnostic gold standard. An artery bypass was established from the superficial temporal artery to a cortical branch of the middle cerebral artery. Perfusion CT scanning was performed at the level of the basal ganglia. Color-coded perfusion maps of cerebral blood volume, cerebral blood flow, and time to peak were calculated.
  
  
  RESULTS
  Preoperative perfusion CT showed significant prolonged time to peak and reduced cerebral blood flow of the affected hemisphere. Postoperative neurological deterioration did not develop in any patient. Computed tomography angiography provided adequate evaluation of the anastomoses as well as the course and caliber of the bypass and confirmed bypass patency in all patients. Postoperative perfusion CT showed improved cerebral hemodynamics with a return to nearly normal perfusion parameters.
  
  
  CONCLUSIONS
  Computed tomography angiography is a noninvasive and reliable tool for evaluating patients with EC-IC bypass. Perfusion CT allows monitoring of hemodynamic changes after bypass surgery. The combination of both modalities enables noninvasive anatomical and functional analysis of superficial temporal artery-middle cerebral artery anastomoses using a single CT protocol. Hemodynamic evaluation of patients with occlusive cerebrovascular disease before and after surgery may improve the prediction of outcome and may help identify patients in whom a bypass procedure can be performed.
authors.affiliation: Institute for Diagnostic Radiology and Neuroradiology, Ernst-Moritz-Arndt-University Greifswald, Germany. soenke.langner@uni-greifswald.de
authors.forename: Soenke
authors.initials: S
authors.lastname: Langner
authors.forename: Steffen
authors.initials: S
authors.lastname: Fleck
authors.forename: Rebecca
authors.initials: R
authors.lastname: Seipel
authors.forename: Henry W S
authors.initials: HW
authors.lastname: Schroeder
authors.forename: Norbert
authors.initials: N
authors.lastname: Hosten
authors.forename: Michael
authors.initials: M
authors.lastname: Kirsch
mesh_terms: D000714:Anastomosis, Surgical; D015901:Angiography, Digital Subtraction; D002533:Cerebral Angiography; D002544:Cerebral Infarction / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation / Q000502:physiology; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging* / Q000601:surgery*; D003545:Cysteine / Q000031:analogs & derivatives; D005500:Follow-Up Studies; D006801:Humans; D016343:Monitoring, Intraoperative; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D058017:Vascular Grafting / Q000379:methods*
chemical_list: D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C059659:technetium Tc 99m bicisate; D003545:Cysteine