|Quantitative Approach to Diffuse Liver Disease|
Diagnosis of Liver Fibrosis by Multifrequency
Viscoelastic Parameter Evaluation in Magnetic Resonance Elastography
Dieter Klatt1, Patrick Asbach1, Uwe Hamhaber1, Sebastian Papazoglou1, Bernd Hamm1, Jürgen Braun1, Ingolf Sack1
1Charité, Berlin, Germany
Multifrequency magnetic resonance elastography was used for separating healthy volunteers from patients with histologically proven liver fibrosis based on hepatic viscoelastic parameters. Measurements were performed on 18 healthy volunteers and 10 patients using a single-shot spin-echo planar imaging sequence. The viscoelastic parameters were determined according to the springpot model which accounts for both elastic and viscous properties of a tissue. The AUROC-value of 92.2% for differentiation between healthy volunteers and patients demonstrates the potential of multifrequency magnetic resonance elastography as a clinical method for diagnosing liver fibrosis.
Value of Shear Wave Attenuation as a Tissue
Characterization Parameter in MR Elastography of the Liver
Meng Yin1, Sudhakar K. Venkatesh2, Yogesh K. Mariappan1, Kevin J. Glaser1, Roger C. Grimm1, Armando Manduca1, Anthony J. Romano3, Richard L. Ehman1
1Mayo Clinic, Rochester, Minnesota, USA; 2National University of Singapore, Singapore; 3Naval Research Laboratory, Washington, District Of Columbia, USA
Magnetic Resonance Elastography (MRE), a non-invasive technique for quantitatively assessing the mechanical properties of soft tissues, has been shown to have high sensitivity and specificity for diagnosing hepatic fibrosis by detecting elevated shear stiffness. Shear wave attenuation, which causes decrease in amplitude with distance, is another potential parameter for tissue characterization that can be obtained with MRE. We implemented a method for estimating shear wave attenuation from wave images and to evaluate this parameter as marker for fibrosis in a series of 63 examinations. The promising results provide continued motivation for further developing shear attenuation inversion algorithm for hepatic MRE.
MR Elastography of Non-Alcoholic Steatohepatitis in
Najat Salameh1, Benoit Larrat2, Jorge Abarca-Quinones1, Isabelle Leclercq1, Ralph Sinkus2, Bernard E. Van Beers1
1Université Catholique de Louvain, Brussels, Belgium; 2Laboratoire Ondes et Acoustique, Paris, France
The aim of our study was to assess the role of MR elastography in staging NASH and to evaluate which parameters influence the visco-elastic measurements in this model of chronic liver disease.
Evaluation of Hepatic Fibrosis with Portal Fraction
and Portal Pressure Gradient Using MRI
Yuenan Wang1, Hyeonjin Kim, R Todd Constable
1Yale University, New Haven, Connecticut, USA
Assessment of hepatic fibrosis is vital to clinical outcomes but non-invasive methods are lack. A previous MRI perfusion study showed portal fraction (PF) was highly correlated with portal pressure (PP) so that PF might be a surrogate of the invasive PP measurement. A recently proposed portal pressure gradient (PPG) method also demonstrated its potential in evaluating the disease. This work aims to compare the performance of these two methods in 31 rats with various degrees of hepatic fibrosis. Both methods were highly correlated with fibrosis scores. PPG demonstrated higher accuracy and sensitivity and did not require contrast agent.
New Proposal for the Staging of
Nonalcoholic Steatohepatitis: Evaluation of Liver Fibrosis on
Natsuko Tsuda1, Masahiro Okada2, Takamichi Murakami2
1Bayer Yakuhin, Ltd., Osaka, Japan; 2Kinki University School of Medicine, Osakasayama, Japan
We investigated whether Gd-EOB-DTPA-enhanced MRI is useful for NASH staging based on the severity of liver fibrosis. Choline-deficient diet-induced NASH rats were subjected to Gd-EOB-DTPA-enhanced MRI. Signal intensities in the liver were measured, and the relative enhancement (RE) was calculated. The time of maximum RE (Tmax) and elimination half-life of RE (T1/2) were compared. The rate of liver fibrosis was measured, and the correlation between the fibrosis rate and Tmax or T1/2 was evaluated. It was found that there was a significant correlation between the fibrosis rate and Tmax or T1/2 (r = 0.90 or 0.97, p < 0.01).
A Liver Function Test Based on Measurement of
Liver-Specific Contrast Agent Uptake
Olof Dahlqvist Leinhard1, 2, Nils Dahlström, 23, Per Sandström4, Torkel Brismar5, Johan Kihlberg, 24, Örjan Smedby, 23, Peter Lundberg1, 2
1Linköpings University, Linköping, Sweden; 2Center for Medical Image Science and Visualization (CMIV), Linköping, Sweden; 3Linköping University, Linköping, Sweden; 4Linköping University Hospital, Linköping, Sweden; 5Karolinska University Hospital, Huddinge, Sweden
Using a simplified model for liver-specific contrast agent dynamics, quantitative analysis of liver-specific contrast agent concentration in the liver and spleen in ten healthy volunteers, seven receiving Gd-EOB-DTPA and three Gd-BOPTA, was performed. An uptake rate was estimated for the hepatobiliary compartment, compensating for differences in renal extraction rate, blood volume and administered dose. In good agreement with known pharmacokinetics, the uptake rate value after 20 minutes was more than 10 times higher for Gd-EOB-DTPA than for Gd-BOPTA, and decreased uptake was noted in four patients with elevated bilirubin levels.
|15:12||89.||Gradient Echo FMRI Study of Oxygenation Changes in
the Livers of Chronic Ethanol-Treated Rats
Manfred Brauer1, Lesley M. Foley2
1University of Guelph, Guelph, Canada; 2Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
Chronic ethanol treatment causes hypoxic liver damage by increasing hepatic oxygen demand and decreasing oxygen supply. Functional MRI can measure tissue oxygenation changes in situ. We used gradient echo fMRI to study liver oxygenation changes in living chronic ethanol-treated rats and controls to show that alcohol greatly decreases and slows the response to hyperoxia, hypoxia and carbogen challenge vs. controls. Liver signal intensities doubled with carbogen inhalation in controls, with no change in alcoholic rats. TE-dependence studies confirm that both SE and GE fMRI studies are consistent with BOLD contrast. Low-volume hemoximetry showed that alcoholic rats had decreased blood oxygen levels in the hepatic artery and portal and hepatic veins under all challenge conditions. Morphometric analysis showed that alcoholic livers’ vasculature was compressed and less responsive to systemic challenge, confirming the fMRI results. This shows that fMRI can noninvasive monitor organ oxygenation status, and that carbogen challenge combined with gradient echo fMRI can readily distinguish healthy from alcoholic liver.
|Evaluation of Hepatic Iron Concentrations by R2*
Magnetic Resonance Imaging in 35 Patients with Iron Overload: Comparison
of R2* Measurements at 1.5T and 3T and Validation with Liver Biopsies
Claudia M. Hillenbrand1, Ralf B. Loeffler1, M. Beth McCarville1, Ruitian Song1, Eileen Hansbury1, Martha Rieman1, Nicole Mortier1, Matthew P. Smeltzer1, Chin-Shang Li1, Fred Hoffer1, Larry Kun1, Russell Ware1, Jane Hankins1
1St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
The aim of this work was to conduct a comprehensive evaluation of liver iron concentration (LIC) obtained by R2*-MRI at 1.5T and 3T in patients with iron overload, and to correlate these R2* values directly with LIC measurements derived from liver biopsies. Further objectives were to study the reliability of R2* LIC measurements as a function of magnetic field strength B0 and to establish a relationship between LIC data measured by R2*-MRI at 3T and 1.5T.
Diagnosis of Hepatic Siderosis with a Novel
Breath-Hold Multi-Echo T2* Sequence in Patients with Chronic Liver
Hersh Chandarana1, Ruth Lim1, Mariela Losada1, Vivian Lee1, Elizabeth Hecht1, Danny Kim1, Bachir Taouli1
1NYU Medical Center, New York, New York, USA
We assessed the performance of a novel multi-echo breath hold T2* sequence for detection of iron in the liver parenchyma, using histopathology as the reference, and we demonstrated significant differences in liver T2* and liver/muscle T2* ratio in patients with iron deposition compared to patients without hemosiderosis. Breath hold T2* sequence had excellent sensitivity, specificity, and accuracy for detection of liver siderosis, when compared to in- and out of phase imaging.
Comparison Between 1.5T and 3T Single Voxel 31P MRS
of Human Liver in Health and Disease
Marzena Wylezinska1, 2, Jeremy Cobbold2, Julie Fitzpatrick2, Philip S. Murphy3, Joe Hajnal2, Isobel Jane Cox2, Simon Taylor-Robinson2
1Hammersmith Hospital, Imperial College London, London, UK; 2Hammersmith Hospital, Imperial College London, London, UK; 3Pfizer, Sandwich, UK
We report the results of a comparison between localized 31P MRS of human liver performed at 1.5T and 3T in the same subjects using the same methodology. Comparisons were performed in terms of spectral resolution, signal to noise (S/N) of PME and PME/PDE ratios.1H decoupling in 31P MR spectra improved resolution at both field strengths (particularly PME and PDE). Further improvement in resolution was evident at 3T. There was an improvement in S/N (~21%). There was a good correlation between the two field strengths, but a small difference in PME/PDE ratios between 1.5T and 3T using the paired test.