Electronic poster

Obesity & Metabolism

Hall B Monday 14:00-16:00 Computer 95

14:00 4614. Abdominal Adipose Tissue Distribution: Regional Differences

Min-Hui Cui¹, Jong Hee Hwang¹, Vlad Tomuta¹, Daniel T. Stein<sup>1

1</sup>Albert Einstein College of Medicine, Bronx, NY, United States

Fifty-eight non-diabetic subjects with a wide range of BMI were studied to evaluate the regional differences of SAT and VAT distribution and the correlations of them with intrahepatic lipid, plasma triglyceride, glucose and FFA levels. Both lean and overweight/obese subjects have most SAT in lower abdomen. However, lean subjects have more VAT while overweight/obese subjects have less VAT in lower abdomen. The relationships between SAT and VAT from different abdominal regions in the lean and overweight/obese subjects with IHL, TG and glucose are also different. Thus conclusions based on one specific AT region should be interpreted with cautions.

14:30 4615. Whole Body Fat Water Imaging at 3 Tesla Using Multi-Echo Gradient Echo

E. Brian Welch^1,2, Johan Berglund³, Heidi J. Silver⁴, Kevin D. Niswender⁵, Morten Bruvold⁶, Joel Kullberg³, Lars Johansson³, Malcolm J. Avison<sup>1

1</sup>Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States; ²MR Clinical Science, Philips Healthcare, Highland Heights, OH, United States; ³Department of Radiology, Uppsala University, Uppsala, Sweden; ⁴Vanderbilt Center for Human Nutrition, Vanderbilt University Medical Center, Nashville, TN, United States; ⁵Vanderbilt Diabetes Research and Training Center, Vanderbilt University Medical Center, Nashville, TN, United States; ⁶MR Clinical Science, Philips Healthcare, Best, Netherlands

The potential of whole body MRI for visualizing adipose tissue distribution has long been recognized. More recently, multi-gradient-echo MR acquisitions have been successfully used at 1.5 Tesla to quickly acquire whole-body data sets. Automated segmentation and quantification of such whole-body fat images into subcutaneous and visceral adipose tissue compartments shows great promise as a tool in studies of obesity and other metabolic syndrome diseases such as diabetes. Most whole-body fat-water imaging has been performed at 1.5 Tesla. However, the availability and prevalence of higher strength 3 Tesla scanners, especially in research settings, justifies the pursuit of robust multi-gradient-echo sequences designed to operate at 3 Tesla. Here we present initial results of a 3T multi-gradient echo whole-body fat-water sequence.

15:00 4616. Rapid, Multi-Slice Fat Water Separated Imaging for Mapping Body Fat

Peter Kellman¹, Diego Hernando², Saurabh Shah³, Z-P Liang², David A. Bluemke¹, Andrew E. Arai<sup>1

1</sup>National Institutes of Health, Bethesda, MD, United States; ²University of Illinois, Urbana, IL, United States; ³Siemens Medical Solutions, Chicago, IL, United States

A rapid multi-slice fat/water separated imaging protocol has been developed for mapping body fat with application to obesity studies. The method combines a 3-echo GRE acquisition and parallel imaging to scan the abdomen and chest in <30 sec. A recently developed joint estimation method for water/fat separation is able to perform robustly in the presence of large B0 field inhomogeneities.

15:30 4617. Automated Quantification of Adipose Tissue Distribution in Children Using a 2-Point Dixon Technique

Joel Kullberg¹, Pär-Arne Svensson², Ann-Katrine Karlsson^3,4, Eira Stokland², Jovanna Dahlgren<sup>3,4

1</sup>Department of Radiology, Uppsala University, Uppsala, N/A, Sweden; ²Department of Pediatric Radiology, The Sahlgrenska University Hospital, Göteborg, Sweden; ³Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden; ⁴The Queen Silvia Children's Hospital, Göteborg, Sweden

A method for assessment of adipose tissue distribution in children is presented. The method utilizes rapid water-fat imaging of 16 slices of the abdomen. A fully automated segmentation algorithm for assessment of visceral and subcutaneous adipose tissue volumes is described. The automatically measured results from 21 volunteer 5-year-olds are compared to those from semi-automated segmentation. Acceptable results were achieved despite the children’s young age and the relatively small adipose tissue volumes measured.

Tuesday 13:30-15:30 Computer 95

13:30 4618. Alterations on Hepatic Glycogen and Lipid Metabolism Following the Induction of Diabetes in the Rat

Ana Francisca Soares^1,2, John Griffith Jones¹, Francisco Veiga², Rui Albuquerque Carvalho<sup>1

1</sup>Life Sciences, Faculty of Sciences and Technology and Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal; ²Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal

The liver stores carbohydrate and lipid after a meal under insulin stimulation. Using deuterated water, we assessed hepatic glycogen synthesis and de novo lipogenesis in healthy and streptozotocin-induced diabetic rats feeding overnight. Hepatic glycogen and lipid content were analyzed by 2H-NMR. Healthy animals showed similar direct and indirect pathway contributions to glycogen. Following Diabetes induction we observed a progressive loss of direct pathway capacity compared to the indirect and also a reduction of de novo lipogenesis. These observations may serve as valuable markers for assessing alterations in hepatic glucose and lipid metabolism during the progress Diabetes.

14:00 4619. In Vivo Monitoring of Treatment Effect of Cryptotanshinone for Non-Alcoholic Fatty Liver Disease in Mice

Hyeon Seung Lee¹, Quan Yu Cai¹, Ki Nam Min², Jong Kook Park², Tae Hwan Kwak², Kyeong Hoon Jeong², Kwan Soo Hong<sup>1

1</sup>MRI, Korea Basic Science Institute, Ochan-Eub, Chungcheonbuk-Do, Korea, Republic of; ²Advanced Biological Research, Mazence Inc, Suwon, Gyeonggi-Do, Korea, Republic of

Treatment of Non-Alcoholic Fatty Liver by Cryptotanshinone in Mouse Models for Hepatic Steatosis

14:30 4620. Functional Magnetic Resonance Imaging of Liver: Effect of Glucose

muhammad E. Haque¹, Ioannis Koktzoglou¹, Wei Li¹, Jo Ann Carbray¹, Pottumarthi V. Prasad<sup>1

1</sup>Radiology, North Shore University Healthcare System, Evanston, IL, United States

One of the primary functions of insulin is disposal of glucose from the blood and inhibition of hepatic glucose production (HGP). Dysfunction of either of these processes can cause development of type II diabetes. Incomplete suppression of HGP is a strong indication of insulin resistance and may be an early marker for development of type II diabetes. Current methods to evaluate insulin resistance are complicated, invasive and hence not used in routine practice. Here we demonstrate feasibility of using BOLD MRI to monitor oxygenation changes in the liver following glucose which may be related to insulin sensitivity.

15:00 4621. Two Site Water Exchange Analysis of Pancreatic T1 Relaxation Reveals the Kinetics and Mechanism of Beta Cell Labeling with Manganese: Implications for Imaging Beta Cell Mass in Diabetes

Patrick Antkowiak¹, Moriel Vandsburger, Frederick Epstein

¹University of Virginia, Charlottesville, VA, United States

The kinetics and mechanism of pancreatic β cell labeling with Mn2+ were investigated. Murine pancreatic T1 relaxation was measured in normals and after treatment with the Ca2+ channel blocker nifedipine. Two site water exchange analysis of pancreatic T1 relaxation provided the intracellular T1 and intracellular fraction, measures of β cell labeling. Increased intracellular T1 and lower intracellular fraction in nifedipine-treated mice confirmed Mn2+ enters β cells through Ca2+ channels. The timecourse of intracellular T1 and fraction in normal mice revealed 3 phases of Mn2+ kinetics: 1) labeling β cells, 2). washout from β cells, 3). nonspecific labeling of other cells.

Lung MRI

Hall B Wednesday 13:30-15:30 Computer 95

13:30 4622. Dynamic Contrast Enhanced Pulmonary Perfusion with Undersampled Stack-Of-Stars and Iterative Highly Constrained Back-Projection

Nathan S. Artz¹, Rafael L. O'Halloran², Mark Schiebler³, James H. Holmes⁴, Sean B. Fain<sup>1,3

1</sup>Medical Physics, University of Wisconsin-Madison, Madison, WI, United States; ²Radiology, Stanford University, Stanford, CA, United States; ³Radiology, University of Wisconsin-Madison, Madison, WI, United States; ⁴Applied Science Laboratory, GE Healthcare, Madison, WI, United States

Pulmonary perfusion was assessed in two healthy volunteers using a contrast-enhanced 3D stack-of-stars GRE sequence. Consecutive groups of 32 projection angles were reconstructed with IHYPR for a temporal resolution of ~1s. The signal vs. time curves demonstrate an expected trend with the pulmonary artery peaking first, followed next by the parenchyma and later the left atrium. Mean transit time, relative pulmonary blood volume and relative pulmonary blood flow maps demonstrate expected results with mean transit times from 3-5 s after the main pulmonary artery trunk and shorter MTT’s in the posterior region due to gravity related effects.

14:00 4623. Comparison of Three Quantification Algorithms (RFM, TSVD, LCC) for Absolute Quantification of Pulmonary Perfusion in Patients with COPD and Pulmonary Embolism by MRI

Mona Salehi Ravesh¹, Michael Puderbach², Sebastian Ley³, Julia Ley-Zaporzhan³, Frank Risse¹, Wilfried Schranz⁴, Wolfhard Semmler¹, Frederik Bernd Laun<sup>1

1</sup>Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany; ²Department of Radiology, German Cancer Research Center, Heidelberg, Germany; ³Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany; ⁴Nonlinear Physics Group, Faculty of Physics, University of Vienna, Vienna, Austria

Lung perfusion is a crucial prerequisite for effective gas exchange. An accurate quantification of pulmonary perfusion is therefore important for diagnostic considerations and treatment planning in various diseases of the lungs.The assessment of pulmonary perfusion by Dynamic Contrast-Enhanced Magnetic Resonance Imaging requires deconvolution of the arterial input function. In the presence of noise this is an ill-posed problem which leads to strongly oscillating, unphysical solutions when it is solved without regularization. In this study a novel method to quantify the pulmonary perfusion is used and compared to the singular value decomposition and L-curve criterion based on simulated and patient data.

14:30 4624. Bronchial Perfusion in the Lungs Observed by Dynamic Contrast-Enhanced MRI

Nabil Saouti¹, Anton Vonk Noordegraaf¹, Michael Ingrisch², J. Tim Marcus<sup>1

1</sup>VU University Medical Center, Amsterdam, Netherlands; ²Ludwig-Maximilian University, Munich, Germany

The aim is to visualise the perfusion of the lungs by the pulmonary and bronchial system separately, based on the fact that a contrast bolus injected intravenously will arrive later in the bronchial than in the pulmonary system. Included were 7 patients with whole left or right pulmonary artery atresia, and 6 chronic thromboembolic pulmonary hypertension patients. Using 3D dynamic contrast-enhanced MRI with 1 s temporal resolution, a 5 s signal-intensity onset delay was measured between open lung or lung region, and obstructed lung (region), providing evidence for bronchial arterial supply after a pulmonary artery obstruction.

15:00 4625. Ventilation/Perfusion MR Imaging of the Lung Using T1-Weighted Ultra-Short Echo Time (UTE) Imaging: Animal Experiment in a 3 T Clinical MRI System

Osamu Togao¹, Marc van Cauteren², Yoshiharu Ohno³, Ivan Dimitrov^1,2, Masaya Takahashi<sup>1

1</sup>Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States; ²MR Clinical Science, Philips Healthcare, Best, Netherlands; ³Radiology, Kobe University Graduate School of Medicine, Kobe , Hyogo, Japan

We have demonstrated that an UTE sequence could bring inherent MR signal of the lung parenchyma that closely related to the parenchymal tissue anatomy. We hypothesize that the capability of the method to acquire inherent MR signal of the lung parenchyma should allow us to assess changes in SI due to inhalation of molecular oxygen or intravenous injection of gadolinium. In the present study, we tested the feasibility of a T1-weighted UTE sequence for assessment of regional pulmonary ventilation/perfusion which is essential for the evaluation of a variety of lung diseases in a 3T clinical MRI system.

Thursday 13:30-15:30 Computer 95

13:30 4626. Self-Referenced Flip Angle Mapping for Hyperpolarized Gas MRI

Eric Frederick^1,2, Mirko Hrovat³, Samuel Patz<sup>2

1</sup>Applied Physics, University of Massachusetts in Lowell, Lowell, MA, United States; ²Radiology, Brigham and Women's Hospital, Boston, MA, United States; ³Mirtech Inc, Brockton, MA, United States

Hyperpolarized noble gas imaging is a non-equilibrium imaging method where gas magnetization is depleted by RF excitations. Due to B_1 field inhomogeneities, this depolarization may not be uniform and therefore a B_1 flip angle map is required to correct the images. This process is typically performed by acquiring an additional set of images. We propose an alternative method where the flip angle map is obtained from one set of images. To do this, we break up a fully sampled image into two undersampled images that are then used for B_1 flip angle mapping. We demonstrate these methods with simulations.

14:00 4627. Towards a Better Understanding of Helium-3 MRI Manual Segmentation Error Using Fuzzy C-Mean Methods

Mohammadreza Heydarian¹, Andrew Wheatley¹, Grace Parraga<sup>1,2

1</sup>Robarts research Institute, London, Ontario, Canada; ²Medical Biophysics, University of Western Ontario, London, On, Canada

Hyperpolarized helium-3 MRI provides a way to visualize and quantify lung function based on segmentation of helium-3 ventilation images. Manual segmentation of 3He ventilation volumes is time consuming and prone to observer error. To address this limitation, we developed and applied a fully automated fuzzy c-mean (FCM) method for segmenting ventilated regions and observed significant associations between the automated and manual segmentation methods. FCM provides a fully automated, robust and efficient method for segmenting ventilated regions of hyperpolarized helium-3 images.

14:30 4628. Optimisation of Velocity Encoding Gradients for Phase Contrast Gas Velocity Taking Diffusion Into Account.

Lionel Martin¹, Xavier Maître¹, Mathieu Sarracanie¹, Marlies Friese², Ludovic de Rochefort¹, Rose-Marie Dubuisson¹, Emeline Boriasse¹, Emmanuel Durand<sup>1

1</sup>Imagerie par Résonance Magnétique Médicale et MultiModalités (UMR8081), Univ Paris-Sud, CNRS, Orsay, France; ²Center for Magnetic Resonance, The University of Queensland, Brisbane, Queensland, Australia

MR flow measurement techniques have mostly been used in liquids. For coherent motion (flow), bipolar gradients induce a phase shift and a signal drop for incoherent motion (diffusion). This effect, negligible for liquids, cannot be neglected for gases. Competition between these two phenomena results in the existence of an optimal FOS that could be theoretically determined. 2D velocity maps of parabolic flows were acquired with different FOS and gases. Results show that velocity error is a function of the FOS and a different optimal FOS is reached for each gas. Thus, they validate our theoretical simulations.

15:00 4629. Hyperpolarized 83Kr MR Relaxation Measurements in Excised Rat Lungs.

Karl F. Stupic¹, Nancy D. Elkins², Galina E. Pavlovskaya³, John E. Repine², Thomas Meersmann, <sup>1,3

1</sup>Department of Chemistry, Colorado State University, Fort Collins, CO, United States; ²Health Science Center, Webb-Waring Institute, University of Colorado, Denver, CO, United States; ³School of Medicine, University of Nottingham, Nottingham, United Kingdom

Hyperpolarized (hp) 83Kr has been previously shown to provide T1 relaxation weighted MRI contrast that is highly sensitive to the surface chemistry in low surface-to-volume model surface systems In the present work 83Kr T1 relaxation in excised rat lungs is investigated as a function of lung inflation. Surprisingly, the relaxation in ex vivo lungs does not change with increased lung inflation (when the effects of airways are eliminated) despite the presumably changing surface to volume ratios in the alveoli. The measured relaxation times are long enough to permit future in vivo studies.

Metabolism Liver & Other I

Hall B Monday 14:00-16:00 Computer 96

14:00 4630. Reproducibility of MRI-Determined Proton Density Fat Fraction (PDFF) Across MR Scanner Platforms and Field Strength

Geraldine Hye Won Kang¹, Michael Schroeder¹, Masoud Shiehmorteza¹, Benjamin Johnson¹, Tanya Wolfson¹, Anthony Gamst¹, Gavin Hamilton¹, Mark Bydder¹, Takeshi Yokoo¹, Claude Sirlin<sup>1

1</sup>Radiology, University of California, San Diego, San Diego, CA, United States

As a result of the growing epidemic of obesity, fatty liver disease has become the most common liver condition in the United States. Thus, there is an increasing need for a noninvasive fat quantification technique. We have developed a T1-independent, T2*-corrected, spectral modeled chemical shift based fat quantification technique, which permits estimation of the proton density fat fraction (PDFF). Here we show that PDFF measured by this technique is reproducible across field strength and vendor and has high accurt5acy using spectroscopy as the reference.

14:30 4631. Association of Obesity with Fatty Infiltration of the Pancreas Diagnosed at MRI

Ely Felker¹, Lorenzo Mannelli¹, Emilio Vega¹, Michael Bloom¹, Hersh Chandarana<sup>1

1</sup>Radiology, NYU Langone Medical Center, New York, NY, United States

In addition to being associated with several metabolic disturbances, such as insulin resistance and diabetes mellitus, obesity causes fat infiltration of several organs, including the heart, liver, and skeletal muscle. The purpose of this study was to characterize the relationship between pancreatic fat infiltration and known markers of obesity. We showed that pancreatic fatty infiltration at MRI was significantly related to central fat volume, peripheral fat volume, and body mass index. Further study will enhance understanding of mechanisms that link obesity to its metabolic complications as well as, perhaps, provide an early marker for incipient insulin resistance and metabolic syndrome.

15:00 4632. Non Alcoholic Fatty Liver Disease (NAFLD) and Visceral Fat: Accurate Spectroscopic and Volumetric Determinations Derived from MR

Khalil N. Salman¹, Puneet Sharma², Bobby Kalb¹, Hiroumi Kitajima², Christina Lurie¹, Miriam Vos³, Diego R. Martin<sup>1

1</sup>Radiology, Emory University, Atlanta, GA, United States; ²Radiology, Emory Healthcare, Atlanta, GA, United States; ³Pediatrics, CHOA, Atlanta, GA, United States

Non Alcoholic Fatty Liver disease(NAFLD) has become a serious problem in the USA. biopsy procedures are invasive and pose a high risk of morbidity. MRS of the liver along with volumetric visceral and subcutaneous fat measurement have shown to be an independent measure of fatty liver. This study investigates the correlation between volumetric fat measurements and hepatic fat fraction using HISTO technique.

15:30 4633. Estimation of the Prevalence of Liver Fibrosis in Patients Receiving Chronic Methotrexate Therapy with MR Elastography

Jun Chen¹, Deana Hoganson², Meng Yin¹, Kevin Glaser¹, Jayant Talwalkar³, Eric Matteson², Richard Ehman<sup>1

1</sup>Department of Radiology, Mayo Clinic, Rochester, MN, United States; ²Division of Rheumatology, Mayo Clinic, Rochester, MN, United States; ³Division of Gastroenterology, Mayo Clinic, Rochester, MN, United States

Methotrexate (MTX) has become the most frequently prescribed disease modifying antirheumatic agent (DMARD) for rheumatoid arthritis (RA), due to its efficacy, low cost and tolerability. An ongoing primary concern of MTX treatment is its potential hepatotoxicity. Guidelines published in 1994 by the American College of Rheumatology (ACR) suggest that serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and albumin be monitored every 4-8 weeks for assessing hepatotoxicity in RA patients receiving MTX. If a patient develops 5 of 9 abnormal AST values within a 12 month time frame or if serum albumin decreases below the normal range, a liver biopsy is recommended. Because of the apparently low rate of clinically significance, MTX related hepatotoxicity, the usefulness and cost-effectiveness of such frequent monitoring, particularly in the absence of risk factors for liver disease have been brought into question. The unavailability of accurate non-invasive hepatic fibrosis detection methods other than biopsy has frustrated clinicians in addressing these important questions. Since its advent 15 years ago [8], Magnetic Resonance Elastography (MRE) has developed into a clinical useful diagnostic technology. This abstract reports interim results from a currently ongoing project using MRE to assess hepatic fibrosis in RA patients who are on MTX treatment seen at our institution.