Proton magnetic resonance imaging and spectroscopy: Assessment of abdominal fat and pancreas fat

Transcription

1 Bond University Targeting metabolic and vascular health with high intensity exercise training in type 2 diabetes CRN-AESS Research Methodology Library 2016 Proton magnetic resonance imaging and spectroscopy: Assessment of abdominal fat and pancreas fat Nathan Johnson The University of Sydney, nathan.johnson@sydney.edu.au Follow this and additional works at: Part of the Nutritional and Metabolic Diseases Commons This work is licensed under a Creative Commons Attribution 4.0 License. Recommended Citation Johnson, N. (2016). Proton magnetic resonance imaging and spectroscopy: Assessment of abdominal fat and pancreas fat [Methodology video]. Bond University. Retrieved from This Research Methodology is brought to you by the CRN-AESS Research Methodology Library at epublications@bond. It has been accepted for inclusion in Targeting metabolic and vascular health with high intensity exercise training in type 2 diabetes by an authorized administrator of epublications@bond. For more information, please contact Bond University's Repository Coordinator.

2 Proton magnetic resonance imaging and spectroscopy: Assessment of abdominal fat and pancreas fat Contributed by: Nathan Johnson, University of Sydney Study: Novel Exercise Therapies for Type 2 Diabetes (HIIT Diabetes) Author: Nathan Johnson Page 1 of 18

3 Table of contents 1 Introduction / Background Terminology and abbreviations Key papers / theoretical basis for the method Theoretical background References Ethical considerations Facility and equipment Testing facility requirements Equipment Personal Protective Equipment (PPE) Training/qualifications/competencies Restricted access Health and safety / Risk Assessment Workflow Before the participant arrives Procedures Post-test care Data handling and management Reporting of information Appendices Participant Information Sheet Participant consent form Participant report example Author: Nathan Johnson Page 2 of 18

4 1 Introduction / Background The location of adipose tissue, particularly in the liver, heart and skeletal muscles appears to be of greater importance than total body fat when determining clinical implications and treatment options for obesity-related disease (1). Whilst most of these ectopic fat depots have been extensively researched, the same cannot be said for fat found in the pancreas, which is situated underneath fat of the abdominal cavity, making in vivo studies difficult (2). Recent advances in non-invasive imaging techniques have increased the capacity for human research on human pancreas fat (3). Emerging evidence suggests that fatty pancreas may contribute significantly to the underlying cardiovascular and metabolic dysfunction observed in obesity and related type 2 diabetes (4,5), including beta cell dysfunction (6,7), and that diet intervention alone or in combination with bariatric surgery, may reduce pancreas fat and improve pancreatic function (8-11). This standard operating procedure (SOP) describes the instructions for MRI and proton magnetic resonance spectroscopy ( 1 H-MRS) scanning for abdominal fat and pancreas fat determination for participants in the Novel Exercise Therapies for Type 2 Diabetes (HIIT Diabetes) research trial. 1.1 Terminology and abbreviations 1 H-MRS proton magnetic resonance spectroscopy T2 spin-spin or transverse relaxation time CH2 methylene ppm parts per million T Tesla MRI magnetic resonance imaging 2 Key papers / theoretical basis for the method Theoretical background The development of non-invasive proton magnetic resonance spectroscopy ( 1 H-MRS) has led to significant advances in the measurement of fat content within organs. The described 1 H-MRS is undertaken using a clinical MRI scanner (usually 1.5 or 3.0 Tesla), which involves using strong magnetic fields and radiowaves to detect signal from protons within a tissue. This is typically undertaken by a specialist provider i.e. private or hospital/research-based radiology clinic. Together with protons from water within a tissue, methylene protons (-CH2-) of triglyceride acyl chains resonating at ~ 1.3 ppm account for the majority of proton signal acquired from tissues such as the liver and pancreas by localized 1 H-MRS at 1.5T (12). The triglyceride concentration within the tissue can be quantified as the ratio of methylene:water signal (13, 6). Author: Nathan Johnson Page 3 of 18

5 Detailed information concerning the development of the method and reliability/validity can be found in relevant literature including: (12, 13). Whilst localised proton spectroscopy is increasingly recognised as the most reliable non-invasive method to quantify organ fat, the technique can be confounded by movement artefact (particularly in the pancreas), and T2 effects. Consideration of these issues can be found elsewhere in the scientific literature e.g. (14) References 1. Lim S, Meigs JB. Ectopic fat and cardiometabolic and vascular risk. Int J Cardiol. 2013;169(3): Hruban RH. History of the pancreas: mysteries of a hidden organ. Bull Hist Med. 2004;78(2): Catanzaro R, Cuffari B, Italia A, Marotta F. Exploring the metabolic syndrome: Nonalcoholic fatty pancreas disease. World J Gastroenterol. 2016;22(34): Kim MK, Chun HJ, Park JH, Yeo DM, Baek KH, Song KH, et al. The association between ectopic fat in the pancreas and subclinical atherosclerosis in type 2 diabetes. Diabetes Res Clin Pract. 2014;106(3): Saisho Y, Butler AE, Meier JJ, Monchamp T, Allen-Auerbach M, Rizza RA, et al. Pancreas volumes in humans from birth to age one hundred taking into account sex, obesity, and presence of type-2 diabetes. Clin Anat. 2007;20(8): Szczepaniak LS, Victor RG, Mathur R, Nelson MD, Szczepaniak EW, Tyer N, et al. Pancreatic Steatosis and Its Relationship to beta-cell Dysfunction in Humans. Diabetes Care. 2012;35(11): Tushuizen ME, Bunck MC, Pouwels PJ, Bontemps S, van Waesberghe JHT, Schindhelm RK, et al. Pancreatic fat content and beta-cell function in men with and without type 2 diabetes. Diabetes Care. 2007;30(11): Steven S, Hollingsworth KG, Small PK, Woodcock SA, Pucci A, Aribisala B, et al. Weight Loss Decreases Excess Pancreatic Triacylglycerol Specifically in Type 2 Diabetes. Diabetes Care. 2016;39(1): Al-Mrabeh A, Hollingsworth KG, Steven S, Taylor R. Morphology of the pancreas in type 2 diabetes: effect of weight loss with or without normalisation of insulin secretory capacity. Diabetologia. 2016;59(8): Lim EL, Hollingsworth KG, Aribisala BS, Chen MJ, Mathers JC, Taylor R. Reversal of type 2 diabetes: normalisation of beta cell function in association with decreased pancreas and liver triacylglycerol. Diabetologia. 2011;54(10): Author: Nathan Johnson Page 4 of 18

6 11. Rossi AP, Fantin F, Zamboni GA, Mazzali G, Zoico E, Bambace C, et al. Effect of moderate weight loss on hepatic, pancreatic and visceral lipids in obese subjects. Nutr Diabetes. 2012; Johnson, N.A., Walton, D.W., Sachinwalla, T., Thompson, C.H., Smith, K., Ruell, P., Stannard, S.R. and George, J. Noninvasive assessment of hepatic lipid composition: advancing understanding and management of fatty liver disorders. Hepatology, 47(5): , Lingvay I, et al. Noninvasive quantification of pancreatic fat in humans. J Clin Endocrinol Metab 2009;94: Sharma P, Martin DR, Pineda N, Xu Q, Vos M, Anania F, Hu X. Quantitative analysis of T2-correction in single-voxel magnetic resonance spectroscopy of hepatic lipid fraction. J Magn Reson Imaging, 2009;29(3): Ethical considerations MRI involves exposure to high magnetic fields, but no ionising radiation. There are no known clinical risks associated with this technique. However, there is a risk of claustrophobia in the scanner and some people may be contraindicated from MRI scanning if they are pregnant or have any ferrous metal materials within their body, in particular: a cardiac pacemaker, metal clips on a cerebral aneurysm, metal particles in the eye or joint replacements. These issues should be discussed and informed consent obtained by the specialist radiography staff prior to scanning. Please see Appendices 9.1 and 9.2 for the Participant Information Sheet and Participant Consent forms. 4 Facility and equipment The described measurement technique requires a whole body MRI scanner and appropriate hardware, including surface coil, respiratory gating as necessary and software and specialist staff to acquire localised spectra. The method described for determination of pancreatic fat for participants in the Novel Exercise Therapies for Type 2 Diabetes (HIIT Diabetes) research trial is for a 1.5T Philips Medical Systems Achieva scanner at Specialist MRI Suite G4-6 RPAH Medical Centre, 100 Carillon Avenue Newtown NSW Australia. Acquisition protocol and sequences may need to be modified to suit the scanner and clinic, as necessary. In all cases acquisition parameters should remain unchanged during the course of a research study. Author: Nathan Johnson Page 5 of 18

7 4.1 Testing facility requirements As required by the clinic to perform clinical MRI scanning. 4.2 Equipment 1.5T Philips Medical Systems Achieva scanner (Best Netherlands). Other equipment as required by the clinic performing clinical MRI scanning and localised spectroscopy Personal Protective Equipment (PPE) As required by the clinic and radiography staff performing clinical MRI scanning. 5 Training/qualifications/competencies Yes No Formal qualification required If yes, please provide details: See Section 6 below. 6 Restricted access The described method is to be implemented by radiography staff with appropriate training and qualifications in MRI. 7 Health and safety / Risk Assessment All scanning should be preceded by appropriate risk assessment. This should be undertaken by radiography staff using site-specific approach/material. For the research trial Novel Exercise Therapies for Type 2 Diabetes (HIIT Diabetes), refer to Risk Assessment and Management procedures of provider: Specialist Magnetic Resonance Imaging RPAH Medical Centre 100 Carillon Ave Newtown NSW 2042 Author: Nathan Johnson Page 6 of 18

8 8 Workflow 8.1 Before the participant arrives The participant should follow any pre-scanning procedures instructed by the radiology clinic/provider. There is no definitive evidence that pre-scanning diet needs to be controlled for prior to pancreatic fat assessment but participants may be advised to refrain from eating for 2 h prior to scanning. 8.2 Procedures 1. Patient risk assessment and consent. 2. Following participant preparation and instruction, the participant should be escorted into the room and placed on the scanner. The standard operating procedure for the Novel Exercise Therapies for Type 2 Diabetes (HIIT Diabetes) research trial is detailed below. Radiographers may use this approach, with adjustment for site-specific needs/hardware/software differences as necessary: 3. File entry: patient with true name, description is HIIT Diabetes (baseline or 12 weeks), comment line include visit number and study ID 4. Positioning (MRI): head first, supine, arms over head 5. Scanning 1: survey (Q body) centre between diaphragm and crests 6. T1 axial (Q body) (arms up breath held) 6.1 ~ slices, top liver to iliac crests (thickness 10mm, gap 10mm) 6.2 multiple breath holds 7. Re-positioning: arms by side 7.1 Surface coil (Flex-L) on abdomen 7.2 Centre pt to coil 7.3 Respiratory bellows on 7.4 FOV optimised for anatomy (but consistent between visits for same pt) 8. Scanning 2: survey (arms down) 9. T1 axial (Q body) arms down breath-hold 10. Spectro (non-water suppressed) free-breathing triggered (32 NSA/measurements) Author: Nathan Johnson Page 7 of 18

9 10.1 SV PRESS TR 3000 Te (40), respiratory trigger, samples 1024, spectral band width Voxel (10x20x10) position along head of pancreas 10.3 Volume shim (shim size larger than voxel e.g. 15x25x15) Shim align - ON 10.4 Visual inspection of voxel position (screen capture) and aim to replicate on subsequent visits 8.3 Post-test care As per standard protocol for the clinic 8.4 Data handling and management 1. Post-processing: run basic scripts to confirm spectroscopy worked 1.1 Select - Spectro view / script / select RUN 1.2 Visually inspect 2 peaks and resolution 2. If error in spectrum re-run steps , may need re-positioning of voxel 3. Copy imaging and spectro data to study external hard-drive 8.5 Reporting of information The workflow describes the operating procedure for the provision of spectroscopy data for research purposes. An example of a de-identified report provided to a research patient can be found in Appendix 9.3. There is currently no accepted clinical application for this technique and thus reporting of the spectroscopy result is not required by a supervising physician (Radiologist). However, the Radiologist may report the abdominal examination on the basis of MRI images/localising images at the provider s discretion. Author: Nathan Johnson Page 8 of 18

10 9 Appendices Author: Nathan Johnson Page 9 of 18

11 9.1 Participant Information Sheet Author: Nathan Johnson Page 10 of 18

12 Author: Nathan Johnson Page 11 of 18

13 Author: Nathan Johnson Page 12 of 18

14 Author: Nathan Johnson Page 13 of 18

15 Author: Nathan Johnson Page 14 of 18

16 Author: Nathan Johnson Page 15 of 18

17 9.2 Participant consent form Author: Nathan Johnson Page 16 of 18

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19 9.3 Participant report example Author: Nathan Johnson Page 18 of 18