Hepatobiliary 2

Tuesday 13 May 2014

Meng Yin¹, Douglas A. Simonetto², Jason L. Bakeberg³, Anuradha Krishnan², Kevin J. Glaser¹, Vijay H. Shah², Christopher J. Ward³, Peter C. Harris³, Michael R. Charlton², Armando Manduca¹, and Richard L. Ehman^1
1Radiology, Mayo Clinic, Rochester, Minnesota, United States, ²Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, United States,³Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, United States

To investigate the utility of MRE-derived mechanical properties in characterizing diseased hepatic tissue, we performed multifrequency 3-D/3-axis MRE on three different mouse models with chronic liver diseases that involved varying degrees of hepatic inflammation, fibrosis, congestion and portal hypertension. Results demonstrated systematic variations in mechanical properties with hepatic inflammation, fibrosis and increased portal pressure. The findings offer preliminary evidence of the potential to extend MRE to distinguish and independently assess necroinflammatory, congestive, and fibrotic processes.

Hanke J. Schalkx¹, Marijn van Stralen², Nicky H.G.M. Peters¹, Wouter B. Veldhuis¹, Maarten S Van Leeuwen¹, Josien P.W. Pluim², Esben T. Petersen¹, and Maurice A.A.J. van den Bosch^1
1Radiology, University Medical Center, Utrecht, Netherlands, ²Image Sciences Institute, University Medical Center, Utrecht, Netherlands

Spin labeling (SL) MRI of the liver has been performed before, but has not been done using Look-Locker readout in humans. We investigated arterial and portal SL-MRI with Look-Locker readout in healthy volunteers to improve quantification by taking regional bolus arrival times into account. Portal venous liver perfusion significantly increased after meal ingestion, while arterial liver perfusion decreased – although not significantly. Postprandial portal venous perfusion change based on SL-MRI with LL readout showed fair correlation with portal venous flow changes. SL-MRI is non-invasive and could potentially contribute to diagnosis and treatment monitoring of liver diseases with elimination of contrast-related risks.

Philippe Garteiser¹, Gaspard D'Assignies¹, Helena S Leitão², Feryel Mouri³, Valérie Vilgrain^1,4, Ralph Sinkus⁵, and Bernard E Van Beers^1,4
1CRB3, INSERM, Paris, 75018, France, ²Center for Neuroscience and cell Biology, University of Coimbra, Coimbra, Coimbra, Portugal, ³Hepatology department, Hôpital Beaujon, AP-HP, Clichy, France, ⁴Radiology department, Hôpital Beaujon, AP-HP, Clichy, France, ⁵Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom

The quantification of liver inflammation has an important clinical impact in chronic liver diseases such as nonalcoholic steatohepatitis and viral hepatitis. Yet, accurate and noninvasive methods for assessing liver inflammation are lacking, and histopathological analysis of liver biopsies remains the gold standard despite its invasiveness and lack of spatial coverage. In this MR elastography study on patients with viral hepatitis, the wave scattering coefficient, a multifrequency mechanical parameter, is found to be mainly determined by inflammation independently from underlying levels of fibrosis. Thus, the measurement of fibrosis and inflammation can reliably be quantified in an independent fashion with MRE.

Alejandro Roldán-Alzate¹, Camilo A Campo¹, Kevin M Johnson², Oliver Wieben¹, and Scott B Reeder^1
1Radiology, University of Wisconsin, Madison, Wisconsin, United States, ²Medical Physics, University of Wisconsin, Madison, Wisconsin, United States

The purpose of this study was to evaluate diurnal changes in mesenteric blood flow in normal subjects and patients with portal hypertension using 4D-flow-MRI. Three patients and seven controls were studied. A total of 5 4D-flow-MRI acquisitions were performed along the day to mimic potential imaging schedules. Healthy controls revealed larger changes in blood flow than those in portal hypertension patients. Reduced hemodynamic response in patients may be due to structural and functional vascular changes resulting from cirrhosis. A comprehensive characterization of portal hypertension hemodynamics using 4D-flow MRI would provide valuable information for stratification of variceal bleeding risk in patients.

Yu Shi^1,2, Kevin J. Glaser¹, Jun Chen¹, and Richard L. Ehman^1
1Mayo Clinic, Rochester, MN, United States, ²Department of radiology, Shengjing hospital, Shenyang, Liaoning, China

This study showed that pancreatic MRE using 3D-EPI MRE is feasible in healthy volunteers at low frequencies (40Hz and 60Hz). The shear stiffness for each individual subject and each pancreatic part was consistent among the subjects (approximately 1.0-1.5 kPa at 40 Hz and 1.5-2.5 kPa at 60 Hz). Using 40-Hz vibrations might be more suitable for pancreatic MRE than 60-Hz motion based on the lower CV and higher ICC for inter-rater agreements. For obese subjects, the waves are less likely to penetrate at 60 Hz, causing noise biases and false stiffness estimates.

Qing Yuan¹, Daniella F Pinho¹, Ivan E Dimitrov^2,3, Ivan Pedrosa^1,2, Yin Xi¹, Ildiko Lingvay⁴, Anna Vanderheiden⁴, and Robert E Lenkinski^1,2
1Radiology, UT Southwestern Medical Center, Dallas, TX, United States, ²Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States, ³Philips Medical Systems, Cleveland, OH, United States, ⁴Internal Medicine, UT Southwestern Medical Center, Dallas, TX, United States

Accurate pancreatic fat quantification using 1H MRS in humans is challenging due to the fact that the pancreas is surrounded by visceral fat, and it moves with respiration. In this study, frame-by-frame acquisition with different respiratory compensation methods was performed. Single frame spectrum analysis shows large variation of fat fraction regardless of the respiratory compensation method utilized. Our results indicate that frame-by-frame acquisition is crucial for 1H MRS of pancreas in vivo. Using the minimum fat fraction from all frames may be a more reliable method when measuring pancreatic fat content.

Xiang He¹, Serter Gumus¹, and Kyong Tae Bae^1
1Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States

Assessment of hemodynamic changes in the liver is particularly challenging due to the dual blood supply. The portal vein and hepatic artery contribution are altered, both globally and regionally, in many liver diseases. In this study, a FAIR-based pulsed ASL approach with cardiac gating was adopted to quantify portal venous fraction in healthy controls. By accounting for the hemodynamic difference of hepatic supplying vessels, the proposed approach can separate the contributions from the portal vein and hepatic artery. This opens new opportunities to detect global and regional alterations in hepatic flow pattern in liver disease patients without contrast agent.

Yi-Xiang Wang¹, Pu-Xuan Lu², Hua Huang², Feng Zhao¹, and Jing Yuan^1
1Dept Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, ²Department of Radiology, the Shenzhen Third People's Hospital, Shenzhen, Guangdong, China

This current study reports the results of intravoxel incoherent motion (IVIM)-based diffusion weighted imaging evaluation of 17 healthy volunteers and 34 liver fibrosis subjects. Pure molecular diffusion (D), the fraction of the diffusion linked to microcirculation (f), and perfusion-related diffusion (D*) were computed. The results demonstrated all D value, f value, and D* value were significantly lower in the fibrosis livers compared with the healthy livers, and progressively lower as the severity of liver fibrosis increased.

Ahmed M. Gharib¹, Simon Lambert², Khaled Z. Abd-Elmoniem¹, Ahmed A. Harouni¹, Theo Heller¹, Caryn Morse¹, and Ralph Sinkus^3
1National Institutes of Health, Bethesda, MD, United States, ²Division of Imaging Sciences and Biomedical Engineering, King’s College, London, England, United Kingdom, ³Division of Imaging Sciences and Biomedical Engineering, King's College, London, England, United Kingdom

Liver MR-elastography (MRE) was performed at 3T on 17 patients with known biopsy proven chronic liver disease. Shear wave speed and the shear wave attenuation were calculated at 26Hz and 58Hz. Both frequencies demonstrated increase shear wave speed that closely follows an increase in fibrosis. However, at 56Hz the shear wave attenuation strongly increases for fibrosis:inflammation ratio <1. This indicates a potential clinical role for this technique to non-invasively assess fibrosis and inflammation in patients with chronic liver disease at 3T. This might be of clinical value in mentoring disease evolution and/or response to therapy in these patients.

Eleanor F Cox¹, Naaventhan Palaniyappan², Guru P Aithal², Indra Neil Guha², and Sue T Francis^1
1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom, ²NIHR Biomedical Research Unit in Gastrointestinal and Liver Diseases, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, United Kingdom

The dynamic postprandial changes in hepatic blood flow and perfusion to a meal challenge are assessed in healthy subjects using phase contrast MRI and multiphase arterial spin labelling. We show an increase in portal vein flow at 25 min and a reduction in hepatic artery (HA) flow at 50 min, reflecting the HA buffer response (HABR). Perfusion is found to increase considerably following meal ingestion and closely match the HABR response to meal ingestion. This protocol will be applied to assess dynamic alterations in blood flow and perfusion in liver disease where flow, perfusion and vasodilation may be altered.