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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.

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.

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.

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.

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).

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.

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.

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.

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.

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.