title: Computerized tomography angiography of ruptured cerebral aneurysms: factors affecting time to maximum contrast concentration.
abstract: OBJECTIVE
  This study was conducted to assess the diagnostic value of three-dimensional computerized tomography (3-D CT) angiography in demonstrating cerebral aneurysms in 42 consecutive patients presenting with acute subarachnoid hemorrhage (SAH).
  
  
  METHODS
  To obtain the volume data for selective visualization of the cerebral arteries without enhancement of the venous system, the time delay was established between the injection of contrast medium and the start of scanning by using two different methods. The circulation time was calculated with Schad's formula in the first 13 cases, but the results were not satisfactory. In the 29 subsequent cases the time delay was established using a single-level dynamic CT prescan. The dynamic prescan demonstrated the statistical differences in peak time with regard to patient age, SAH grade, and the postresuscitation state after cardiopulmonary arrest. The 3-D CT angiograms were generated from the volume data by using a voxel transmission method. Computerized tomography angiography obtained after optimally adjusted time delay demonstrated the contour of the cerebral arteries in 97% of cases, and aneurysms were detected in 93%. Enhancement of the cavernous sinus and major cortical veins was avoided. Even in patients who suffered cardiopulmonary arrest, images of the major arteries were clearly demonstrated after resuscitation.
  
  
  CONCLUSIONS
  In an emergency situation, CT angiography with a dynamic prescan may be an alternative to magnetic resonance angiography or digital subtraction angiography in the diagnosis of ruptured aneurysms. This modality would also be useful for the precise assessment of small aneurysms, blebs, and aneurysms adjacent to the cavernous sinus.
authors.affiliation: Osaka Prefectural Senshu Critical Care Medical Center, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakajima
authors.forename: T
authors.initials: T
authors.lastname: Yoshimine
authors.forename: H
authors.initials: H
authors.lastname: Yoshida
authors.forename: K
authors.initials: K
authors.lastname: Sakashita
authors.forename: M
authors.initials: M
authors.lastname: Okamoto
authors.forename: M
authors.initials: M
authors.lastname: Kishikawa
authors.forename: K
authors.initials: K
authors.lastname: Yagi
authors.forename: J
authors.initials: J
authors.lastname: Yokota
authors.forename: T
authors.initials: T
authors.lastname: Hayakawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017542:Aneurysm, Ruptured / Q000150:complications / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007275:Injections, Intravenous; D002532:Intracranial Aneurysm / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D011446:Prospective Studies; D013345:Subarachnoid Hemorrhage / Q000209:etiology; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media