title: Hepatic blood perfusion estimated by dynamic contrast-enhanced computed tomography in pigs: limitations of the slope method.
abstract: OBJECTIVE
  The aim of this study was to determine whether dynamic contrast-enhanced computed tomography (DCE-CT) and the slope method can provide absolute measures of hepatic blood perfusion from the hepatic artery (HA) and portal vein (PV) at experimentally varied blood flow rates.
  
  
  METHODS
  Ten anesthetized 40-kg pigs underwent DCE-CT of the liver during periods of normocapnia (normal flow), hypocapnia (decreased flow), and hypercapnia (increased flow), which were induced by adjusting the ventilation. Reference blood flows in the HA and PV were measured continuously by surgically placed ultrasound transit-time flowmeters. For each capnic condition, the DCE-CT-estimated absolute hepatic blood perfusion from the HA and PV were calculated using the slope method and compared with flowmeter-based absolute measurements of hepatic perfusions and relative errors were analyzed.
  
  
  RESULTS
  The relative errors (mean ± SEM) of the DCE-CT based perfusion estimates were -21% ± 23% for HA and 81% ± 31% for PV during normocapnia, 9% ± 23% for HA and 92% ± 42% for PV during hypocapnia, and 64% ± 28% for HA and -2% ± 20% for PV during hypercapnia. The mean relative errors for HA were not significantly different from 0 during hypocapnia and normocapnia, and the DCE-CT slope method could detect relative changes in HA perfusion between scans. Infusion of contrast agent led to significantly increased hepatic blood perfusion, which biased the PV perfusion estimates.
  
  
  CONCLUSIONS
  Using the DCE-CT slope method, HA perfusion estimates were accurate at low and normal flow rates, whereas PV perfusion estimates were inaccurate and imprecise. At high flow rate, both HA perfusion estimates were significantly biased.
authors: Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark. mw@pet.auh.dk
authors: Michael
authors: M
authors: Winterdahl
authors: Michael
authors: M
authors: Sørensen
authors: Susanne
authors: S
authors: Keiding
authors: Frank V
authors: FV
authors: Mortensen
authors: Aage K O
authors: AK
authors: Alstrup
authors: Søren B
authors: SB
authors: Hansen
authors: Ole L
authors: OL
authors: Munk
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003287:Contrast Media; D005260:Female; D008099:Liver / Q000098:blood supply* / Q000473:pathology / Q000502:physiology; D010477:Perfusion; D015203:Reproducibility of Results; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media