title: Imaging of blood flow in cerebral arteries with dynamic helical computed tomography angiography (DHCTA) using a 64-row CT scanner.
abstract: BACKGROUND
  Cerebral computed tomography angiography (CTA) depicts a structural image of intracranial arteries without providing much time-resolved information on blood flow dynamics. Current CT technology allows obtaining of rapidly repeated helical scans during the arterial contrast filling phase after an intravenous contrast injection.
  
  
  OBJECTIVE
  To report our experience on dynamic CT imaging in determining the direction of contrast filling within proximal intracranial arteries of operated cerebral artery aneurysm patients. Such dynamic information can help detect vascular occlusion or severe spasm. The method is here referred to as dynamic helical CT angiography (DHCTA).
  
  
  METHODS
  We retrospectively collected image and related technical data for 23 patients who underwent DHCTA and CTA during their first postoperative day after cerebral artery aneurysm surgery. For DHCTA, we had helically scanned a 4-cm tissue volume three times in succession with a 64-row CT scanner at intervals of 2.6 s during arterial contrast filling after an intravenous contrast injection. We assessed how well DHCTA succeeded in demonstrating the direction of contrast filling in the proximal intracranial arteries, evaluated clinically relevant structural information provided by DHCTA and CTA, and compared radiation doses for the two methods.
  
  
  RESULTS
  For 21 patients, DHCTA outlined the direction of contrast filling in proximal intracranial arteries. As to arterial spasm and residual filling of the operated aneurysm, CTA and DHCTA gave similar information. Radiation doses were higher (P<0.000001) for DHCTA than for CTA at 120 kV tube voltage. At 100 kV, the difference was smaller, but doses for DHCTA still exceeded (P<0.05) those for CTA.
  
  
  CONCLUSIONS
  DHCTA gave dynamic information unobtainable with CTA and could prove useful in selected clinical settings.
authors.affiliation: Helsinki Medical Imaging Center, Helsinki University Central Hospital, Helsinki, Finland. johanna.pekkola@hus.fi
authors.forename: J
authors.initials: J
authors.lastname: Pekkola
authors.forename: M
authors.initials: M
authors.lastname: Kangasniemi
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D001783:Blood Flow Velocity; D002533:Cerebral Angiography / Q000379:methods*; D003287:Contrast Media; D005260:Female; D006439:Hemodynamics; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed / Q000379:methods*; D014283:Triiodobenzoic Acids
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; C054871:ioversol