No abstract

The aim of this study was to assess the feasibility of using non-invasive MR elastography for determining the stage of liver fibrosis. Twenty-five consecutive patients who had liver biopsy for suspicion of chronic liver disease were included in the study. The stage of fibrosis on the biopsies was assessed according to the METAVIR scoring system from F0, no fibrosis, to F4, cirrhosis. MR elastography was performed by transmitting low-frequency (65 Hz) mechanical waves into the liver with a transducer placed at the back of the patients. The MR pulse sequence was a motion-sensitized spin-echo sequence, phase-locked to the mechanical excitation. The phase maps were processed to obtain shear elasticity and shear viscosity maps. The mean hepatic shear elasticity increased with increasing stage of fibrosis. The mean elasticity was 2.24 +/- 0.23 kPa in the 11 patients without substantial fibrosis (F0-F1 grades), 2.56 +/- 0.24 kPa in the four patients with substantial fibrosis (F2-F3) and 4.68 +/- 1.61 kPa in the 10 patients with cirrhosis (F4). The differences between groups were statistically significant (p

Large A(z) values for elasticity (>0.990 for scores > or = F2, > or = F3, and F4) show that MR elastography was accurate in liver fibrosis staging and superior to biochemical testing with APRIs.

Hepatic flow parameters measured with MR imaging correlate with the severity of cirrhosis and portal hypertension. Doppler US parameters are only weakly correlated with portal pressure.

Purpose:To describe the use of MRI and a cortical-compartment model to measure the glomerular filtration rate (GFR), and compare the results with those obtained with the Patlak-Rutland model. Materials and Methods:Dynamic MRI of rabbit kidneys was performed during and after injection of gadoterate dimeglumine. The enhancement curves in the aorta and the kidney were analyzed with the cortical-compartment and Patlak-Rutland models to assess the GFR.Results: A substantial correlation was observed between the GFR measured with MRI using the cortical-compartment model and the plasma clearance of 51Cr-EDTA (r ϭ 0.821, P ϭ 0.004). No significant correlation was observed between the 51Cr-EDTA clearance (r ϭ 0.628, P ϭ 0.052) and the GFR obtained with the Patlak-Rutland model in regions of interest (ROIs) encompassing the renal cortex and medulla. A Bland and Altman analysis showed that GFR cortical compartment agreed better with the 51Cr-EDTA clearance compared to GFR Patlak when ROIs were limited to the cortex. However, the GFR values obtained by MRI were lower than the plasma clearance of 51Cr-EDTA. Conclusion:MRI with a cortical-compartment model provides more accurate assessments of glomerular filtration than the Patlak-Rutland model.