Article

Dynamic measurements of total hepatic blood flow with Phase Contrast MRI.

Department of Radiology, University Hospital, Place Victor Pauchet, 80054 Amiens cedex 1, France.
European journal of radiology (impact factor: 2.65). 12/2008; 73(1):119-24. DOI:10.1016/j.ejrad.2008.09.032
Source: PubMed

ABSTRACT To measure total hepatic blood flow including portal and proper hepatic artery flows as well as the temporal evolution of the vessel's section during a cardiac cycle.
Twenty healthy subjects, with a mean age of 26 years, were explored. Magnetic resonance imaging blood flow measurements were carried out in the portal vein and the proper hepatic artery. MR studies were performed using a 1.5T imager (General Electric Medical Systems). Gradient-echo 2D Fast Cine Phase Contrast sequences were used with both cardiac and respiratory gatings. Data analysis was performed using a semi-automatic software built in our laboratory.
The total hepatic flow rate measured was 1.35+/-0.18L/min or 19.7+/-4.6mL/(minkg). The proper hepatic artery provided 19.1% of the total hepatic blood flow entering the liver. Those measurements were in agreement with earlier studies using direct measurements. Mean and maximum velocities were also assessed and a discrepancy between our values and the literature's Doppler data was found. Measurements of the portal vein area have shown a mean variation, defined as a "pulsatility" index of 18% over a cardiac cycle.
We report here proper hepatic artery blood flow rate measurements using MRI. Associated with portal flow measurements, we have shown the feasibility of total hepatic flowmetry using a non-invasive and harmless technique.

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    Article: A three-compartment model of the C-peptide-insulin dynamic during the DIST test.
    J Geoffrey Chase, Klaus Mayntzhusen, Paul D Docherty, Steen Andreassen, Kirsten A McAuley, Thomas F Lotz, Christopher E Hann
    [show abstract] [hide abstract]
    ABSTRACT: Dynamic insulin sensitivity (SI) tests often utilise model-based parameter estimation. This research analyses the impact of expanding the typically used two-compartment model of insulin and C-peptide kinetics to incorporate a hepatic third compartment. The proposed model requires only four C-peptide assays to simulate endogenous insulin production (uen), greatly reducing the cost and clinical burden. Sixteen subjects participated in 46 dynamic insulin sensitivity tests (DIST). Population kinetic parameters are identified for the new compartment. Results are assessed by model error versus measured data and repeatability of the identified SI. The median C-peptide error was 0% (IQR: -7.3, 6.7)%. Median insulin error was 7% (IQR: -28.7, 6.3)%. Strong correlation (r=0.92) existed between the SI values of the new model and those from the original two-compartment model. Repeatability in SI was similar between models (new model inter/intra-dose variability 3.6/12.3% original model -8.5/11.3%). When frequent C-peptide samples may be available, the added hepatic compartment does not offer significant diagnostic, repeatability improvement over the two-compartment model. However, a novel and successful three-compartment modelling strategy was developed which provided accurate estimation of endogenous insulin production and the subsequent SI identification from sparse C-peptide data.
    Mathematical biosciences 12/2010; 228(2):136-46. · 1.30 Impact Factor
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Keywords

direct measurements
 
General Electric Medical Systems
 
Gradient-echo 2D Fast Cine Phase Contrast sequences
 
harmless technique
 
literature's Doppler data
 
Magnetic resonance imaging blood flow measurements
 
mean age
 
mean variation
 
measure total hepatic blood flow
 
portal flow measurements
 
portal vein
 
portal vein area
 
proper hepatic artery
 
proper hepatic artery flows
 
semi-automatic software
 
temporal evolution
 
total hepatic blood flow
 
total hepatic flow rate
 
total hepatic flowmetry
 
vessel's section
 

Thierry Yzet