title: Measurement of hepatic perfusion with dynamic computed tomography: assessment of normal values and comparison of two methods to compensate for motion artifacts.
abstract: OBJECTIVE
  To assess normal values of hepatic perfusion by dynamic, single-section computed tomography, to compare two methods of data processing (a smoothing with a fitting procedure), and to evaluate the influence of motion artifacts.
  
  
  METHODS
  Twenty-five volunteers with no history or suspicion of liver disease were examined (age range, 32.8-81.1 years). All examinations were subjectively ranked into groups 1 through 3 according to the degree of motion artifacts (negligible, moderate, severe). All data were processed with a smoothing procedure and a pharmacokinetic fitting procedure (TopFit). The arterial, portal venous, and total hepatic perfusion; the hepatic perfusion index (HPI); and the arterial/portal venous ratio (A/P ratio) were calculated with both procedures.
  
  
  RESULTS
  Mean hepatic perfusion, as assessed with the fitting procedure and the smoothing procedure, respectively, was as follows: arterial, 0.20 and 0.22 mL x min(-1) x mL(-1); portal venous, 1.02 and 1.24 mL x min(-1) x mL(-1); total perfusion, 1.22 and 1.47 mL x min(-1) x mL(-1); HPI, 16.4% and 15.4%; and A/P ratio, 0.20 and 0.19. The differences were significant for the portal venous and total hepatic perfusion. The portal venous and total hepatic perfusion values showed significant differences between group 1 and groups 2 and 3 for both procedures. HPI and the A/P ratio showed no significant differences at all.
  
  
  CONCLUSIONS
  Motion artifacts and the type of data processing influence the assessment of the arterial, portal venous, and total hepatic perfusion but do not influence measurement of the HPI and the A/P ratio.
authors.affiliation: Department of Radiology, University of Vienna, Austria. till.bader@univie.ac.at
authors.forename: T R
authors.initials: TR
authors.lastname: Bader
authors.forename: F
authors.initials: F
authors.lastname: Grabenwöger
authors.forename: R W
authors.initials: RW
authors.lastname: Prokesch
authors.forename: W
authors.initials: W
authors.lastname: Krause
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008099:Liver / Q000098:blood supply* / Q000000981:diagnostic imaging*; D008102:Liver Circulation; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009038:Motion; D011169:Portal Vein / Q000000981:diagnostic imaging; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*