|MRI & MRS of Liver Steatosis|
Hepatic Fat Quantification by Low Flip-Angle
Multi-Echo Gradient-Echo MR Imaging: A Clinical Study with Validation
with MR Spectroscopy
Takeshi Yokoo1, Mark Bydder1, Gavin Hamilton1, Michael S. Middleton1, Jefferey Schwimmer, Joel Lavine, Terek Hassanein, Heather Patton, Nicholas Pinto1, Richard Znamirowski1, Lillian Pacheco1, Claude B. Sirlin1
1University of California at San Diego, San Diego, California , USA
Noninvasive hepatic fat quantification is an increasingly important area of application of MR technology. Several new MR imaging strategies have been proposed in an attempt to account for the T1 and T2* relaxation effects, and to improve the accuracy and reliability of fat quantification. In this presentation, we describe results from a prospective clinical study in which low flip-angle multi-echo gradient-echo imaging is used to predict the proton-density fat fraction measured by MR spectroscopy.
Quantification of Hepatic Steatosis with MRI:
Validation in the Ob/ob Mouse at 3T
Catherine Diane Gard1, Thomas Frances Warner1, Huanzhou Yu2, Ann Shimakawa2, Charles A. McKenzie3, Jean H. Brittain4, Scott B. Reeder1
1University of Wisconsin-Madison, Madison, Wisconsin, USA; 2GE Healthcare, Menlo Park, California , USA; 3University of Western Ontario, London, Canada; 4GE Healthcare, Madison, Wisconsin, USA
Early diagnosis of hepatic steatosis with non-invasive quantitative biomarkers is a critical unmet need in the detection and evaluation of non-alcoholic fatty liver disease. In this work we validate fat quantification of hepatic steatosis in a range of tissue fat percentages in the ob/ob mouse model of hepatic steatosis using IDEAL (Iterative Decomposition with Echo Asymmetry and Least-squares estimation). We compare fat-fraction measured with IDEAL to histological evaluation and total lipid extraction using the Folch method. Excellent correlation between IDEAL, histology and lipid extraction is observed. These results demonstrate validation of MRI for quantification of hepatic steatosis in vivo.
Rapid T2 and Lipid-Water Imaging of the
Liver with Radial IDEAL GRASE
Maria I. Altbach1, Zhiqiang Li1, Scott W. Squire1, Arthur F. Gmitro1, Ali Bilgin1, Christian Graff1, Eric Outwater1
1University of Arizona, Tucson, Arizona , USA
A radial Gradient and Spin Echo (GRASE) method has been developed for liver imaging. The method allows for the quantitative characterization of liver pathologies based on T2 values and lipid-water information.
Correction for Multipeak Fat Spectrum When Estimating
T2* in the Presence of Fat
Huanzhou Yu1, Scott B. Reeder2, Ann Shimakawa1, Charles A. McKenzie3, Jean H. Brittain4
1GE Healthcare, Menlo Park, California , USA; 2University of Wisconsin, Madison, Wisconsin, USA; 3University of Western Ontario, London, Canada; 4GE Healthcare, Madison, Wisconsin, USA
Simultaneous estimation of water, fat and T2*, achieved by algorithms such as T2*-IDEAL, is important in the evaluation hepatic fatty infiltration and iron overload. Fat was previously modeled as a single resonant frequency. However, fat has multiple spectral peaks that confound the estimation of fat content and T2*. In particular, T2* may be substantially under-estimated in the presence of fat, which would lead to overestimation of liver iron stores. In this work, we model a more accurate fat spectrum in the T2*-IDEAL algorithm and propose a spectrum self-calibration method that provides improved T2* estimation with no additional data required.
Quantification of Hepatic Steatosis with MRI: the
Effects of Accurate Fat Spectral Modeling
Scott B. Reeder1, 2, Philip Robson2, Huanzhou Yu3, Ann Shimakawa3, Catherine D. Gard1, Charles A. McKenzie4, Jean H. Brittain5
1University of Wisconsin, Madison, Wisconsin, USA; 2Beth Israel-Deaconess Medical Center, Boston, Massachusetts, USA; 3GE Healthcare, Menlo Park, California , USA; 4University of Western Ontario, London, Canada; 5GE Healthcare, Madison, California , USA
Accurate non-invasive quantification of hepatic steatosis is an important unmet need in the diagnosis and management of non-alcoholic fatty liver disease (NAFLD). In this work, we describe the use of IDEAL, a chemical-shift based water-fat separation method, with a modified reconstruction that accounts for the signal from the multiple peaks of fat (“multipeak reconstruction”) and compare this method with MR spectroscopy (PRESS) in 31 patients. Excellent agreement between IDEAL and PRESS with a slope near 1.0 is achieved only when multipeak reconstruction is used, demonstrating the importance of all spectral peaks of fat when quantifying hepatic fat content.
Fat Quantification Using SPIO as a Surrogate Marker
for Iron Accumulation in the Liver
Sebastian Sugay1, Mark Bydder2, Takeshi Yokoo2, Gavin Hamilton2, Nick Pinto2, Richard Znamirowski2, Eli Soumekh2, Tanya Wolfson2, Lillian Pacheco2, Claude Sirlin2
1John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA; 2University of California, San Diego, California , USA
In this abstract, we show that accounting for T2* decay of water and fat using a 6-point imaging protocol produces stable measurements in fat fraction (FF) despite experimental, SPIO-induced perturbations in T2*. As T2* decreased, the 6 point FF measurements remained unchanged, while the 2 point measurements underestimated FF.
Quantification of the Hepatic Fatty
Infiltration and the Metabolite Concentrations Using Magnetic Resonance
Spectroscopy and in and Out of Phase Imaging
Sophie Cavassila1, Adriana Bucur1, Hélène Ratiney1, Cristina Cudalbu1, Olivier Beuf1, Frank Pilleul1, 2
1CNRS UMR 5220, Inserm U630, INSA-Lyon, Université de Lyon, Université Lyon 1, Villeurbanne, France; 2Hospices Civils de Lyon, Lyon, France
Despite the increasing prevalence of non-alcoholic fatty liver disease, the criteria used to diagnose the disorder remain poorly defined. Non invasive methods such as proton magnetic resonance spectroscopy (MRS), diffusion-weighted imaging, double-echo imaging (DEI) have been developed in order to substitute liver biopsy which is the gold standard. For this study, twelve patients with suspected liver diseases were investigated by MR imaging and spectroscopy of the liver. Both saturated lipids/water and unsaturated lipids/water ratios determined by MRS showed strong correlations with the percentage of liver steatosis determined by DEI. Moreover, the levels (relative to water) of the groups of metabolites at 3.2ppm and 3.5ppm determined by MRS showed also correlations with the percentage of liver steatosis determined by DEI.
Validation of Hepatic Fat Quantified on 3T MRI Via
Histopathologic Correlation in Patients with Non-Alcoholic
Hero K. Hussain1, Elif A. Oral, Suzan Rohrer, Barbara McKenna, Frank J. Londy, Marko K. Ivancevic, Thomas L. Chenevert
1University of Michigan, Ann Arbor, Michigan, USA
The dual-flip MRI method at 3T is reliable to measure hepatic fat. It correlates well with quantitative histopathologic measures and MRS, though unlike MRS, offers full-liver mapping of fat content and overcomes heterogeneity.
Non-Invasive Quantification of Hepatic Steatosis with
3.0 Tesla Magnetic Resonance Spectroscopy in Patients Undergoing Liver
Jochem Reinier van Werven1, H. A. Marsman1, A. J. Nederveen1, F. J. ten Kate1, T. M. van Gulik1, J. Stoker1
1Academic Medical Center, Amsterdam, Netherlands
Hepatic steatosis is a risk factor in liver surgery. Liver biopsy remains the gold standard. 1H-MRS is a non-invasive alternative. The purpose of this study was to quantify hepatic steatosis with 3.0T 1H-MRS in patients undergoing liver resection.1H-MRS was performed preoperatively in twenty patients undergoing liver resection. Intra-operatively biopsies were taken for histopathological and biochemical analysis. 1H-MRS measurements of hepatic fat correlated with these assessments. 1H-MRS measurements could differentiate between different grades of hepatic steatosis.3.0T 1H-MRS can measure hepatic fat content and correlates with histopathological and biochemical analysis. It is also able to discriminate between grades of steatosis.
Effects of T1 and T2* Relaxation on Fat
Quantification by Gradient Echo Imaging
Mark Bydder1, Takeshi Yokoo1, Gavin Hamilton1, Michael S. Middleton1, Claude Sirlin1
1University of California San Diego, San Diego, California , USA
MRI is increasingly applied to the non-invasive assessment of steatosis. A linear correlation is often assumed between MRI estimates of fat and a gold standard (e.g. histology). We show that T1 and T2* relaxation can introduce nonlinearity in a typical liver imaging protocol.