title: Comparison of partial volume effects in arterial and venous contrast curves in CT brain perfusion imaging.
abstract: OBJECTIVE
  In brain CT perfusion (CTP), the arterial contrast bolus is scaled to have the same area under the curve (AUC) as the venous outflow to correct for partial volume effects (PVE). This scaling is based on the assumption that large veins are unaffected by PVE. Measurement of the internal carotid artery (ICA), usually unaffected by PVE due to its large diameter, may avoid the need for partial volume correction. The aims of this work are to examine i) the assumptions behind PVE correction and ii) the potential of selecting the ICA obviating correction for PVE.
  
  
  METHODS
  The AUC of the ICA and sagittal sinus were measured in CTP datasets from 52 patients. The AUCs were determined by i) using commercial CTP software based on a Gaussian curve-fitting to the time attenuation curve, and ii) by simple integration of the time attenuation curve over a time interval. In addition, frames acquired up to 3 minutes after first bolus passage were used to examine the ratio of arterial and venous enhancement. The impact of selecting the ICA without PVE correction was illustrated by reporting cerebral blood volume (CBV) measurements.
  
  
  RESULTS
  In 49 of 52 patients, the AUC of the ICA was significantly larger than that of the sagittal sinus (p = 0.017). Measured after the first pass bolus, contrast enhancement remained 50% higher in the ICA just after the first pass bolus, and 30% higher 3 minutes later. CBV measurements were significantly lowered when the ICA was used without PVE correction.
  
  
  CONCLUSIONS
  Contradicting the assumptions underlying PVE correction, contrast in the ICA was significantly higher than in the sagittal sinus, even 3 minutes after the first pass of the contrast bolus. PVE correction might lead to overestimation of CBV if the CBV is calculated using the AUC of the time attenuation curves.
authors.affiliation: Department of Radiology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Riordan
authors.affiliation: Department of Radiology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Edwin
authors.initials: E
authors.lastname: Bennink
authors.affiliation: Department of Radiology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: Dankbaar
authors.affiliation: Department of Radiology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Max A
authors.initials: MA
authors.lastname: Viergever
authors.affiliation: Department of Radiology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Birgitta K
authors.initials: BK
authors.lastname: Velthuis
authors.affiliation: Department of Radiology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Ewoud J
authors.initials: EJ
authors.lastname: Smit
authors.affiliation: Department of Radiology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: Hugo W A M
authors.initials: HW
authors.lastname: de Jong
mesh_terms: D019540:Area Under Curve; D001810:Blood Volume; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging* / Q000502:physiology; D003287:Contrast Media; D003392:Cranial Sinuses / Q000000981:diagnostic imaging* / Q000502:physiology; D006801:Humans; D055420:Perfusion Imaging / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media