title: Effect of extended CT perfusion acquisition time on ischemic core and penumbra volume estimation in patients with acute ischemic stroke due to a large vessel occlusion.
abstract: OBJECTIVE
  It has been suggested that CT Perfusion acquisition times <60 seconds are too short to capture the complete in and out-wash of contrast in the tissue, resulting in incomplete time attenuation curves. Yet, these short acquisitions times are not uncommon in clinical practice. The purpose of this study was to investigate the occurrence of time attenuation curve truncation in 48 seconds CT Perfusion acquisition and to quantify its effect on ischemic core and penumbra estimation in patients with acute ischemic stroke due to a proximal intracranial arterial occlusion of the anterior circulation.
  
  
  METHODS
  We analyzed CT Perfusion data with 48 seconds and extended acquisition times, assuring full time attenuation curves, of 36 patients. Time attenuation curves were classified as complete or truncated. Ischemic core and penumbra volumes resulting from both data sets were compared by median paired differences and interquartile ranges. Controlled experiments were performed using a digital CT Perfusion phantom to investigate the effect of time attenuation curve truncation on ischemic core and penumbra estimation.
  
  
  RESULTS
  In 48 seconds acquisition data, truncation was observed in 24 (67%) cases for the time attenuation curves in the ischemic core, in 2 cases for the arterial input function and in 5 cases for the venous output function. Analysis of extended data resulted in smaller ischemic cores and larger penumbras with a median difference of 13.2 (IQR: 4.3-26.0) ml (P<0.001) and; 12.4 (IQR: 4.1-25.7) ml (P<0.001), respectively. The phantom data showed increasing ischemic core overestimation with increasing tissue time attenuation curve truncation.
  
  
  CONCLUSIONS
  Truncation is common in patients with large vessel occlusion and results in repartitioning of the area of hypoperfusion into larger ischemic core and smaller penumbra estimations. Phantom experiments confirmed that truncation results in overestimation of the ischemic core.
authors: Department of Radiology, Academic Medical Center, Amsterdam, the Netherlands.
authors: Jordi
authors: J
authors: Borst
authors: Department of Radiology, Academic Medical Center, Amsterdam, the Netherlands; Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, the Netherlands.
authors: Henk A
authors: HA
authors: Marquering
authors: Department of Radiology, Academic Medical Center, Amsterdam, the Netherlands.
authors: Ludo F M
authors: LF
authors: Beenen
authors: Department of Radiology, Academic Medical Center, Amsterdam, the Netherlands.
authors: Olvert A
authors: OA
authors: Berkhemer
authors: Department of Radiology, University Medical Center Utrecht, the Netherlands.
authors: Jan Willem
authors: JW
authors: Dankbaar
authors: Department of Radiology, University Medical Center Utrecht, the Netherlands.
authors: Alan J
authors: AJ
authors: Riordan
authors: Department of Radiology, Academic Medical Center, Amsterdam, the Netherlands.
authors: Charles B L M
authors: CB
authors: Majoie
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D020521:Stroke / Q000000981:diagnostic imaging* / Q000503:physiopathology; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*