Cornelius von Morze¹, Gene-Yuan Chang², Peder E Larson¹, Hong Shang¹, Robert A Bok¹, Jason C Crane¹, Marram P Olson¹, C.T. Tan³, Sarah J Nelson¹, John Kurhanewicz¹, David Pearce², and Daniel B Vigneron^1
1Department of Radiology & Biomedical Imaging, UCSF, San Francisco, California, United States, ²Department of Medicine, UCSF, San Francisco, California, United States, ³ISOTEC, Sigma-Aldrich, Miamisburg, Ohio, United States

MRSI of hyperpolarized (HP) ¹³C-labeled compounds is a powerful new approach for localized non-invasive studies of tissue metabolism in vivo. The purpose of this study was to characterize tissue-specific alterations in the metabolism of HP gluconeogenic precursors ¹³C-lactate and ¹³C-pyruvate by rat liver and kidneys in response to fasting. Seven rats were studied by 13C MRSI of both HP ¹³C-lactate and ¹³C-pyruvate in both normal fed and 24h fasting states. Significant metabolic modulations associated with fasting were identified in the localized metabolite data resulting from these spectroscopic imaging experiments.

Tania Buehler¹, Lia Bally², Ayse Sila Dokumaci¹, Christoph Stettler², and Chris Boesch^1
1Depts. Radiology and Clinical Research, University Bern, Bern, Switzerland, ²Division of Endocrinology, Diabetes and Clinical Nutrition, Inselspital Bern, Bern, Switzerland

The need to administer exogenous insulin in type 1 diabetes mellitus (T1DM) subjects generally increases the risk of exercise-related hypoglycemia. A better understanding of exercise-associated fuel metabolism is essential to develop strategies to improve glucose stability. In this study two types of exercise protocols (moderate (CONT) and high intermittent intensity (IHE)) were performed in T1DM subjects to evaluate glucose requirements and hepatic and myocellular glycogen consumption during the two different exercise interventions. The IHE protocol provides a feasible strategy to reduce glucose requirements during the exercise. This is correlated with an increased consumption of hepatic glycogen.

Andrew Lewis¹, Chloe McCallum¹, Jack Miller^1,2, Lisa Heather¹, and Damian J Tyler^1
1Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom, ²Department of Physics, University of Oxford, Oxford, United Kingdom

The mechanism of action of metformin in type II diabetes is uncertain, but may involve altered cellular redox state and carbohydrate metabolism. We used hyperpolarized [1-13C]pyruvate magnetic resonance spectroscopy to investigate the acute effects of a metformin infusion upon cardiac and hepatic metabolism in Wistar rats (n=6-7 per group). An infusion of 50mg metformin increased the cardiac [1-13C]lactate to [1-13C]pyruvate ratio compared to a control infusion (P<0.05), without affecting pyruvate dehydrogenase flux. These findings suggest an increase in the size of the cardiac lactate pool and/or increased lactate dehydrogenase activity, demonstrating that metformin has previously unknown effects upon cardiac metabolism.

Sharon Janssens¹, Klaas Nicolay¹, and Jeanine J. Prompers^1
1Biomedical NMR, Eindhoven University of Technology, Eindhoven, Noord-Brabant, Netherlands

Excessive consumption of sugars in caloric sweetened beverages causes hepatic steatosis, which is attributed to de novo lipogenesis. In this study we implemented a non-invasive method for the direct in vivo measurement of de novo lipogenesis in the liver using localized ¹H MRS with ¹³C editing to detect ¹³C-labeled liver lipids after oral administration of [U-¹³C₆] glucose. Using this method we studied the effects of caloric and non-caloric sweeteners on liver lipid metabolism in rats. In contrast to glucose and aspartame, fructose increased liver lipid content, which was associated with an increased conversion of ¹³C-labeled glucose to liver lipids.

Kathryn Murray¹, Caroline Hoad¹, Jill Garratt², Carolyn Costigan¹, Arvind Batra³, Britta Siegmund³, Yirga Falcone², Jan Smith², Eleanor Cox¹, Jan Paul¹, David Humes², Susan Francis¹, Luca Marciani², Robin Spiller², and Penny Gowland^1
1Sir Peter Mansfield Imaging Centre, Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom, ²Nottingham Digestive Diseases Biomedical Research Centre, Nottingham University Hospitals, Nottingham, United Kingdom, ³Gastroenterology, Rheumatology, Infectious Diseases, Charité – Universitätsmedizin, Berlin, Germany

This study highlights the relationship between adipose deposition, adipokine secretion and intestinal inflammation using obese and non-obese patients with diverticular disease. DIXON imaging was used to determine VAT, SAT and TAT amounts and these volumes were compared to concentrations of adiponectin, leptin and calprotectin. These novel insights will help improve our understanding of the relationship between visceral fat, obesity and inflammation.

Douglas E Befroy^1,2, Kitt Falk Petersen², Douglas L Rothman^1,3, and Gerald I Shulman^2,4
1Diagnostic Radiology, Yale University School of Medicine, New Haven, CT, United States, ²Internal Medicine, Yale University School of Medicine, New Haven, CT, United States, ³Biomedical Engineering, Yale University School of Medicine, New Haven, CT, United States, ⁴Howard Hughes Medical Institute, New Haven, CT, United States

Insulin resistance is accompanied by derangements in a variety of parameters of muscle metabolism including insulin-stimulated glucose disposal and glycogen synthesis as well as basal rates of mitochondrial metabolism. To date, technological and methodological limitations have required that each of these parameters be assessed as distinct experiments, which can complicate comparison between studies. We have developed an innovative dual ¹³C-tracer method to assess muscle glucose utilization and oxidative metabolism during a single ¹³C-MRS study at 7 Tesla. The ability to comprehensively examine muscle substrate utilization in vivo will advance our understanding of skeletal muscle metabolism.

Maria Hahnemann^1,2, Oliver Kraff², Stefan Maderwald², Soeren Johst², Mark E. Ladd^2,3, Harald H. Quick^2,4, and Thomas Lauenstein^1
1Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany, ²Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany, ³Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, ⁴High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany

Contrast-enhanced MR imaging of the small bowel was performed in 12 healthy volunteers at 1.5T and 7T. Quality of MR images was directly compared between 1.5T and 7T. Image impairment by artifacts was separately investigated for 1.5T and 7T. MR images of the small bowel at 7T can be generated with an image quality that fulfills diagnostic requirements. Despite an increasing number of artifacts at 7T, tissue contrast and image quality were equivalent as compared with those achieved with 1.5T.

Maria L. Hahnemann^1,2, Oliver Kraff¹, Stefan Maderwald¹, Soeren Johst¹, Mark E. Ladd^1,3, Harald H. Quick^1,4, and Thomas C. Lauenstein^2
1Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany, ²Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany, ³Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, ⁴High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany

T2-w imaging (coronal and axial TrueFISP, coronal HASTE) of 12 healthy volunteers was evaluated qualitatively and quantitatively at 7 Tesla and 1.5 Tesla. MR images of the small bowel at 7T can be generated with an image quality that is sufficient for routine diagnostics. Despite an increasing number of artifacts at 7T, tissue contrast and image quality were equivalent as compared with those achieved with 1.5T.

Michael D Repplinger^1,2, Perry J Pickhardt², Douglas R Kitchin², Jessica B Robbins², Timothy J Ziemlewicz², and Scott B Reeder^2,3
1Emergency Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States, ²Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States, ³Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States

The aim of our study was to determine the test characteristics of an MRI protocol consisting of unenhanced, contrast-enhanced, and DWI to diagnose appendicitis. This was a prospective study including patients ≥12 years for whom a CT was ordered to evaluate for appendicitis. We enrolled 165 patients; all images were interpreted by three radiologists. Sensitivity and specificity (95% CI) were 95.7% (84.7-99.5%) and 88.8% (81.4-93.6%) for unenhanced MRI with DWI, 95.7% (84.5-99.5%) and 88.1% (80.2-93.2%) for CE-MRI, and 97.9% (88.1-100%) and 92.7% (85.9-96.4%) for CE-MDCT. We conclude that this MRI protocol was as accurate as CE-MDCT to diagnose appendicitis.

Alex Lewis¹, Mathew Bernbeck¹, Richard Barth¹, and Shreyas Vasanawala^2
1Radiology, Stanford University, Stanford, CA, United States, ²Stanford University, Stanford, CA, United States

All pediatric appendicitis MRIs from 1/2014 to 9/2014 with diffusion and post contrast sequences at our institution were retrospectively identified and randomized into two groups (36 each). All studies were scored by three readers of varying experience with appendicitis MRI for delineation of the appendix, confidence of assessment of acute appendicitis and perforation/abscess after each series. Appendicitis was present in 18/72 (25%) cases and complication in 6/72 (8%). An appendix or appendiceal candidate was identified in 36, 18 and 56% of cases for readers 1, 2 and 3 respectively with SS, increasing to 89, 36 and 100% for SS+CE, and 53, 19 and 100% for SS+DW. Sensitivity and specificity of detection of appendicitis and perforation/abscess were also evaluated. Results demonstrate that both DWI and contrast enhanced imaging increase performance of MRI for diagnosis of appendicitis.