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Keywords: Liver, Quantitative Imaging, Fat, Data analysis

Proton density fat fraction (PDFF) is an established quantitative-imaging-biomarker for hepatic -fat quantification, but typically requires specialized confounder-corrected chemical-shift-encoded (CSE) magnetic-resonance-imaging (MRI) pulse sequences. We developed and assessed the feasibility of deep learning to infer hepatic PDFF maps from conventional T1-weighted-in-and-opposed-phase (T1w-IOP) MRI.  Using PDFF maps reconstructed from CSE-MRI as reference, we trained a convolutional-neural-network (CNN) to infer voxel-wise PDFF maps from T1w-IOP MRI.  The CNN was evaluated using both internal and external test datasets. Participant-level median CNN-inferred-PDFF were compared with reference CSE-MRI using linear regression, intraclass correlation, and Bland-Altman analysis.  Median CNN-inferred PDFF agreed closely with reference CSE-MRI PDFF.  

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Shu-Fu Shih^1,2, Sevgi Gokce Kafali^1,2, Kara L. Calkins³, and Holden Wu^1,2
1Radiological Sciences, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, United States, ²Bioengineering, University of California Los Angeles, Los Angeles, CA, United States, ³Pediatrics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, United States

Keywords: Liver, Fat

3D self-navigated multi-echo stack-of-radial Dixon sequence has been used to quantify fat and R₂* with free-breathing acquisitions. To compensate motion, motion-resolved compressed sensing (CS) uses self-navigation for data binning, and applies sparsity constraint along the dimension of motion states. However, this approach does not explicitly model non-rigid motion in the liver. In addition to artifacts caused by respiratory motion, hardware imperfection such as gradient nonlinearity can lead to artifacts and affect the image quality. In this work, use a phase-preserving beamforming-based coil sensitivity estimation method and non-rigid motion compensation in a CS model to improve free-breathing PDFF and R₂* quantification.

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Donovan Tripp¹, Karl P Kunze^1,2, Michael Crabb¹, Radhouene Neji^1,2, Claudia Prieto^1,3, and René Botnar^1,3,4
1School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ²MR Research Collaborations, Siemens Healthcare Limited, Camberley, United Kingdom, ³School of Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile, ⁴Institute for Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile

Keywords: Liver, Low-Field MRI

Through T₁, T₂, and fat fraction mapping, MRI is a formidable tool for the comprehensive assessment of liver health, but has been held back by slow, 2D, single-parameter mapping sequences. We propose a novel respiratory-motion-corrected framework to acquire all three of these maps from a single 6.5-minute scan, on the latest generation of 0.55T scanner. The resulting maps are 3D, with 3 mm isotropic resolution, and co-registered, making them suitable for multiparametric assessment of tissue health. Liver joint T₁, T₂, and fat fraction maps are in good agreement with reference values and first in-vivo scans provide promising image quality.

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Utsav Shrestha¹, Juan Pablo Esparza¹, Sanjaya Satapathy², Jason Vanatta³, and Aaryani Tipirneni-Sajja^1,4
1The University of Memphis, Memphis, TN, United States, ²North Shore University Hospital/Northwell Health, Manhasset, NY, United States, ³University of Tennessee Health Science Center, Memphis, TN, United States, ⁴St. Jude Children’s Research Hospital, Memphis, TN, United States

Keywords: Liver, Liver

Hepatic iron concentration (HIC) and fat fraction (FF) is assessed by chemical-shift encoded multi-spectral fat-water model that incorporates single- or dual-R2* correction. In this study, we designed a realistic virtual liver model simulating the combined presence of hepatic steatosis and iron overload using histology data and synthesized MRI signal in the virtual model using Monte-Carlo simulation to compare the accuracy of the R2* models to quantify FF in the presence of iron. Our results show that single-R2* is consistent than dual-R2* in estimating FF for HIC<=10 mg Fe/g after which both R2* models show higher error.

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Xiaodong Zhong¹, Stephan A.R. Kannengiesser², Pedro Itriago Leon³, Vibhas Deshpande⁴, and Takeshi Yokoo^5
1MR R&D Collaborations, Siemens Medical Solutions USA, Inc., Los Angeles, CA, United States, ²MR Application Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany, ³MR R&D Collaborations, Siemens Medical Solutions USA, Inc., Dallas, CA, United States, ⁴MR R&D Collaborations, Siemens Medical Solutions USA, Inc., Austin, CA, United States, ⁵Department of Radiology and Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States

Keywords: Liver, Quantitative Imaging, R2*, Iron, LIC, free-breathing

This study compared free-breathing stack-of-radial and breath-hold Cartesian multi-echo GRE MRI for liver iron quantification at 1.5T and 3T to the reference standard R2-based liver iron concentration (LIC) at 1.5T (FerriScan), in patients at risk for liver iron overload. Agreement was observed for liver iron concentration measured by free-breathing 3D stack-of-radial GRE MRI compared the reference standard R2-based LIC, as well as breath-hold 3D Cartesian GRE MRI. With further validation in larger number of iron-overloaded subjects, 3D stack-of-radial GRE MRI may allow free-breathing R2* and LIC mapping at both 1.5T and 3T.

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Mary Kate Manhard^1,2, Anandh Kilpattu Ramaniharan¹, Jean A Tkach^1,2, Andrew T Trout^1,2, Jonathan R Dillman^1,2, and Amol Pednekar^1,2
1Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, ²Radiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States

Keywords: Liver, Quantitative Imaging

Quantitative parametric mapping is an increasingly important tool for non-invasive assessment of liver disease. Conventional parametric mapping techniques require multiple breath-held acquisitions providing limited coverage. A free-breathing multi-inversion spin and gradient echo (MI-SAGE) technique is demonstrated to simultaneously estimate T₁, T₂, and T₂* over the whole-liver in a single scan of less than 1 minute. In 11 research participants, hepatic T₁, T₂, and T₂* estimates obtained using the free-breathing MI-SAGE technique were comparable to those obtained using modified Lock Locker, multiple gradient and spin echo, and multiple gradient echo sequences respectively and exhibited good to excellent (ICC>0.77) repeatability and reproducibility.

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Jonathan K. Stelter¹, Kilian Weiss², Elizabeth Huaroc Moquillaza¹, Felix N. Harder¹, Marcus R. Makowski¹, Rickmer F. Braren¹, and Dimitrios C. Karampinos^1
1Department of Diagnostic and Interventional Radiology, Technical University of Munich, Munich, Germany, ²Philips Healthcare, Hamburg, Germany

Keywords: Liver, Relaxometry

Volumetric T1 and T2 relaxation mapping is of interest in the characterization of diffuse and oncological liver diseases. Current methods for free-breathing whole-liver relaxation mapping have primarily been optimized to quantify a water-specific T1, are restricted to large voxel sizes in the feet-head-direction, and are not compatible with self-navigation. The present work proposes a novel methodology for Free-breathing Isotropic resolution self-Navigated B1-insensitive whOle-liver simultaneous water-specific T1 and T2 mapping (FINO). Phantom results illustrate the accuracy of the method and in vivo results demonstrate the feasibility of whole-liver water-specific T1 and T2 mapping at an isotropic resolution of 3mm in 6min.

Lujie Li¹, Kan Deng², Yinhong Zhang¹, and Shi-ting Feng^1
1the First Affiliated Hospital of Sun Yet-sen University, Guangzhou, China, ²Philips Healthcare, Guangzhou, China

Keywords: Liver, Quantitative Imaging

Corrected T₁ (cT₁) is potential to be a novel imaging biomarker, which was based on T₁ mapping corrected for iron content. The results of this study showed the high correlation between cT1 value and NAFLD activity, without correlation with fibrosis. There was high accuracy of cT₁ to identify normal liver and liver with NAFLD, as well as mild and severe NAFLD. The severer inflammation, the higher heterogeneity of cT₁ mapping. Thus, cT₁ may be used for evaluating liver inflammation of patient with NAFLD, especially for those without severe fibrosis, and may evaluate heterogeneity further.

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Jiahui Li¹, Zheng Zhu¹, Kevin J. Glaser¹, Yi Sui¹, Douglas A. Simonetto², Alina M Allen², Armando Manduca¹, Sudhakar K. Venkatesh¹, Vijay H. Shah², Richard L. Ehman¹, and Meng Yin^1
1Radiology, Mayo Clinic, Rochester, MN, United States, ²Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, United States

Keywords: Liver, Liver

To evaluate MR imaging biomarkers in monitoring chronic liver diseases, we analyzed longitudinal MRE-assessed liver stiffness (LS) and proton density fat fraction (PDFF) measurements in 46 patients with alcoholic liver disease (ALD) or nonalcoholic fatty liver disease (NAFLD). Results demonstrated that yearly LS change rate was significantly associated with current LS and PDFF change rate in NAFLD, although with low correlation (R²=0.30, p=0.01). ALD patients had bidirectional changes in LS/PDFF change rate but not significant correlation (R²=0.20, p=0.10). We conclude that longitudinal MRE-LS and MRI-PDFF provide independent and complementary assessments of disease status and dynamic change in ALD and NAFLD.

Fengxian Fan¹, Yanli Jiang¹, Jie Zou¹, Pin Yang¹, and Jing Zhang^1
1Department of Magnetic Resonance, Lanzhou University Second Hospital, Lanzhou, China

Keywords: Liver, Diffusion/other diffusion imaging techniques, histogram analysis; stretched exponential model; diffusion kurtosis imaging

This study aims to evaluate the potential role of histogram analysis of diffusion kurtosis imaging (DKI) and stretched exponential model (SEM) for preoperative prediction of liver fibrosis and inflammation. Histogram metrics were extracted from mean diffusion (MD), mean kurtosis (MK), distributed diffusion coefficient (DDC) and intravoxel heterogeneity index (α). The histogram metrics of MD, DDC and α demonstrate significant correlation with inflammation, the histogram metrics of MD and DDC were significantly different between S0-1 and ≥S2. Histogram analysis of DKI and SEM may be potentially useful for evaluating heterogeneity of liver.

Zhou Wei¹, Yupin Liu*¹, Xiaohuan Li¹, Zhiyuan Chen¹, Robert Grimm², and Yunzhu Wu^3
1Department of Radiology, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Traditional Chinese Medicine, Guangzhou, China, ²MR Application Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany, ³MR Scientific Marketing, SIEMENS Healthineers Ltd., Shanghai, China

Keywords: Liver, Liver

Liver fibrosis (LF) is a dynamic, reversible process which can result in liver failure. Diagnosis and monitoring of LF are clinically important. This study was to evaluate the diagnostic capability of the model based on multiparametric MRI in identifying significant LF in patients with chronic hepatitis B (CHB). The predictive model based on multiparametric MRI further could improve diagnostic accuracy and serve for identifying significant LF in CHB patients, also provide a reliable basis for clinical diagnosis and treatment.

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Yingying Ning¹, Iris Y. Zhou¹, Nicholas J Rotile¹, Avery Boice¹, Johanna Schaub², Scott Turner², and Peter Caravan^1
1Athinoula A. Martinos Center for Biomedical Imaging, Institute for Innovation in Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States, ²Pliant Therapeutics, Inc., South San Francisco, CA, United States

Keywords: Liver, Liver, liver fibrogenesis

A collagen-binding molecular MR probe CM-101 was employed to non-invasively assess liver fibrosis and the anti-fibrotic effects of a novel αvβ6/αvβ1 integrin antagonist treatment in bile duct-ligated rats. Reduction of fibrosis was detected by collagen imaging and correlated with morphometric assessment of fibrosis from histology. CM-101 enhanced MR is a useful tool to monitor drug treatment response in chronic liver disease.

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James Rice^1,2, Thekla Oechtering^2,3, Kevin M Johnson^2,4, Oliver Wieben^2,4, Scott B Reeder^2,4,5,6, and Alejandro Roldan-Alzate^1,2,6
1Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, United States, ²Radiology, University of Wisconsin-Madison, Madison, WI, United States, ³Radiology, Universität zu Lübeck, Lübeck, Germany, ⁴Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, ⁵Emergency Medicine, University of Wisconsin-Madison, Madison, WI, United States, ⁶Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States

Keywords: Liver, Modelling

4D flow MRI can be used to assess hemodynamics in the hepatic circulation system. This study presents a framework for in vitro hemodynamic evaluation of hepatic flow. One patient-specific in vitro model was created representing an anatomically realistic portal vein and hepatic artery and connected to a physiologic flow loop. The model was imaged with 4D flow MRI to assess hemodynamics. Altering hepatic artery and left gastric vein resistance changed flow proportions and velocities in the portal vein, highlighting the benefit of using in vitro modeling for systematic evaluation of 4D flow MRI in the liver.

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Keywords: Liver, Preclinical, MEX

Quantitative MRI can elucidate the complex microstructural changes in liver disease. The MEX method estimates macromolecular fraction, such as collagen, and can potentially aid in this task.

Rats and mice were given CCl₄ to induce liver fibrosis and canned using a 7T scanner with MEX sequence (selective suppression and magnetization exchange) and macromolecular fraction (F) and T₁ were extracted. Histology quantitative evaluation of collagen and inflammation scoring was conducted.   

F-values of fibrotic rats and mice were significantly increased and correlated with quantitative collagen percentage. T₁ was significantly elevated with higher inflammation scores.

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Keywords: Liver, Vessels

4D flow MRI can aid in diagnosing pathologies associated with hemodynamic changes in the portal vein, such as portal hypertension. Normal reference ranges for portal venous flow are lacking but essential for future clinical implementation. We report reference values based on radial 4D flow MRI measurements of mean flow, velocity, and effective diameter in the portal venous vasculature in 44 healthy subjects (59% female, 18-74 years). Faint helical and linear flow are physiological flow patterns observed in the portal vein. This study provides normative values for emerging clinical applications of 4D flow MRI currently under development.

Keywords: Liver, Velocity&Flow, Vessels