title: Optimal sequence timing of CT angiography and perfusion CT in patients with stroke.
abstract: OBJECTIVE
  Standard stroke CT protocols start with non-enhanced CT followed by perfusion-CT (PCT) and end with CTA. We aimed to evaluate the influence of the sequence of PCT and CTA on quantitative perfusion parameters, venous contrast enhancement and examination time to save critical time in the therapeutic window in stroke patients.
  
  
  METHODS
  Stroke CT data sets of 85 patients, 47 patients with CTA before PCT (group A) and 38 with CTA after PCT (group B) were retrospectively analyzed by two experienced neuroradiologists. Parameter maps of cerebral blood flow, cerebral blood volume, time to peak and mean transit time and contrast enhancements (arterial and venous) were compared.
  
  
  RESULTS
  Both readers rated contrast of brain-supplying arteries to be equal in both groups (p=0.55 (intracranial) and p=0.73 (extracranial)) although the extent of venous superimposition of the ICA was rated higher in group B (p=0.04). Quantitative perfusion parameters did not significantly differ between the groups (all p>0.18), while the extent of venous superimposition of the ICA was rated higher in group B (p=0.04). The time to complete the diagnostic CT examination was significantly shorter for group A (p<0.01).
  
  
  CONCLUSIONS
  Performing CTA directly after NECT has no significant effect on PCT parameters and avoids venous preloading in CTA, while examination times were significantly shorter.
authors: Institute of Clinical Radiology, University of Munich, Munich, Germany. morhard@nrad.de
authors: D
authors: D
authors: Morhard
authors: C D
authors: CD
authors: Wirth
authors: M F
authors: MF
authors: Reiser
authors: G
authors: G
authors: Schulte-Altedorneburg
authors: B
authors: B
authors: Ertl-Wagner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002533:Cerebral Angiography / Q000379:methods*; D002544:Cerebral Infarction / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020521:Stroke / Q000000981:diagnostic imaging* / Q000209:etiology; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult