title: Assessment of hepatic extraction fraction and input relative blood flow using dynamic hepatocyte-specific contrast-enhanced MRI.
abstract: OBJECTIVE
  To assess the feasibility to use dynamic hepatocyte-specific contrast-enhanced MRI (DHCE-MRI) as an imaging-based liver function test, and to compare two methods for deconvolutional analysis (DA) in healthy human subjects.
  
  
  METHODS
  T(1)-weighted DHCE-MRI with the hepatocyte-specific contrast medium Gd-EOB-DTPA was performed in 20 healthy volunteers. DA was performed using truncated singular value decomposition (TSVD) and Fourier analysis with an appended tail (FA+Tail). Hepatic extraction fraction (HEF) and input relative blood flow (irBF) were calculated for each liver segment. A computer simulation comparing the standard deviation (SD) of TSVD and FA+tail at different levels of signal-to-noise (SNR) ratio was performed. The results obtained were compared using descriptive statistics, the Wilcoxon matched pairs test and the variance ratio test.
  
  
  RESULTS
  Median HEF was 0.201 and 0.205 using TSVD and FA+tail, respectively (P = 0.086). The corresponding results for irBF was 0.240 and 0.239 (P = 0.51). TSVD yielded a smaller SD, although the difference was not significant (P = 0.068 for HEF and P = 0.84 for irBF). The computer simulation showed that TSVD is more stable than FA+tail at most levels of SNR.
  
  
  CONCLUSIONS
  DHCE-MRI with Gd-EOB-DTPA enables the calculation of HEF and irBF. We regard these parameters as being markers of hepatic parenchymal function.
authors.affiliation: Karolinska Institutet, Sweden. henrik.nilsson@ki.se
authors.forename: Henrik
authors.initials: H
authors.lastname: Nilsson
authors.forename: Anders
authors.initials: A
authors.lastname: Nordell
authors.forename: Roberto
authors.initials: R
authors.lastname: Vargas
authors.forename: Lena
authors.initials: L
authors.lastname: Douglas
authors.forename: Eduard
authors.initials: E
authors.lastname: Jonas
authors.forename: Lennart
authors.initials: L
authors.lastname: Blomqvist
mesh_terms: D000328:Adult; D003287:Contrast Media / Q000493:pharmacokinetics; D005240:Feasibility Studies; D005583:Fourier Analysis; D019786:Gadolinium DTPA / Q000493:pharmacokinetics; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008099:Liver / Q000098:blood supply*; D008111:Liver Function Tests; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA