title: Optimal Computed Tomographic Perfusion Scan Duration for Assessment of Acute Stroke Lesion Volumes.
abstract: The minimal scan duration needed to obtain reliable lesion volumes with computed tomographic perfusion (CTP) has not been well established in the literature.
  
  
  
  We retrospectively assessed the impact of gradual truncation of the scan duration on acute ischemic lesion volume measurements. For each scan, we identified its optimal scan time, defined as the shortest scan duration that yields measurements of the ischemic lesion volumes similar to those obtained with longer scanning, and the relative height of the fitted venous output function at its optimal scan time.
  
  
  
  We analyzed 70 computed tomographic perfusion scans of acute stroke patients. An optimal scan time could not be determined in 11 scans (16%). For the other 59 scans, the median optimal scan time was 32.7 seconds (90th percentile 52.6 seconds; 100th percentile 68.9 seconds), and the median relative height of the fitted venous output function at the optimal scan times was 0.39 (90th percentile 0.02; 100th percentile 0.00). On the basis of a linear model, the optimal scan time was T0plus 1.6 times the width of the venous output function (P<0.001; R2=0.49).
  
  
  
  This study shows how the optimal duration of a computed tomographic perfusion scan relates to the arrival time and width of the contrast bolus. This knowledge can be used to optimize computed tomographic perfusion scan protocols and to determine whether a scan is of sufficient duration. Provided a baseline (T0) of 10 seconds, a total scan duration of 60 to 70 seconds, which includes the entire downslope of the venous output function in most patients, is recommended.
authors.affiliation: From the Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA.
authors.forename: Aimen S
authors.initials: AS
authors.lastname: Kasasbeh
authors.affiliation: From the Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA.
authors.forename: Søren
authors.initials: S
authors.lastname: Christensen
authors.affiliation: From the Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA.
authors.forename: Matus
authors.initials: M
authors.lastname: Straka
authors.affiliation: From the Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA.
authors.forename: Nishant
authors.initials: N
authors.lastname: Mishra
authors.affiliation: From the Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA.
authors.forename: Michael
authors.initials: M
authors.lastname: Mlynash
authors.affiliation: From the Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA.
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
authors.affiliation: From the Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA.
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Albers
authors.affiliation: From the Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA. lansberg@stanford.edu.
authors.forename: Maarten G
authors.initials: MG
authors.lastname: Lansberg
mesh_terms: D002560:Cerebrovascular Circulation / Q000502:physiology*; D006801:Humans; D055420:Perfusion Imaging; D012189:Retrospective Studies; D020521:Stroke / Q000000981:diagnostic imaging*; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards
keywords: magnetic resonance imaging; perfusion imaging; reperfusion; stroke