| 1. |
- Andersson, Jonathan, et al.
(författare)
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Estimating the cold-induced brown adipose tissue glucose uptake rate measured by 18F-FDG PET using infrared thermography and water-fat separated MRI
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Brown adipose tissue (BAT) expends chemical energy to produce heat, which makes it a potential therapeutic target for combating metabolic dysfunction and overweight/obesity by increasing its metabolic activity. The most well-established method for measuring BAT metabolic activity is glucose uptake rate (GUR) measured using 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). However, this is expensive and exposes the subjects to potentially harmful radiation. Cheaper and safer methods are warranted for large-scale or longitudinal studies. Potential alternatives include infrared thermography (IRT) and magnetic resonance imaging (MRI). The aim of this study was to evaluate and further develop these techniques. Twelve healthy adult subjects were studied. The BAT GUR was measured using 18F-FDG PET during individualized cooling. The temperatures of the supraclavicular fossae and a control region were measured using IRT during a simple cooling protocol. The fat fraction and effective transverse relaxation rate of BAT were measured using MRI without any cooling intervention. Simple and multiple linear regressions were employed to evaluate how well the MRI and IRT measurements could estimate the GUR. Results showed that both IRT and MRI measurements correlated with the GUR. This suggest that these measurements may be suitable for estimating the cold-induced BAT GUR in future studies.
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| 2. |
- Boersma, Greta J., et al.
(författare)
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Altered Glucose Uptake in Muscle, Visceral Adipose Tissue, and Brain Predict Whole-Body Insulin Resistance and may Contribute to the Development of Type 2 Diabetes: A Combined PET/MR Study
- 2018
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Ingår i: Hormone and Metabolic Research. - : Georg Thieme Verlag KG. - 0018-5043 .- 1439-4286. ; 50:8
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Tidskriftsartikel (refereegranskat)abstract
- We assessed glucose uptake in different tissues in type 2 diabetes (T2D), prediabetes, and control subjects to elucidate its impact in the development of whole-body insulin resistance and T2D. Thirteen T2D, 12 prediabetes, and 10 control subjects, matched for age and BMI, underwent OGTT and abdominal subcutaneous adipose tissue (SAT) biopsies. Integrated whole-body 18F-FDG PET and MRI were performed during a hyperinsulinemic euglycemic clamp to asses glucose uptake rate (MRglu) in several tissues. MRglu in skeletal muscle, SAT, visceral adipose tissue (VAT), and liver was significantly reduced in T2D subjects and correlated positively with M-values (r = 0.884, r = 0.574, r = 0.707 and r = 0.403, respectively). Brain MRglu was significantly higher in T2D and prediabetes subjects and had a significant inverse correlation with M-values (r = -0.616). Myocardial MRglu did not differ between groups and did not correlate with the M-values. A multivariate model including skeletal muscle, brain and VAT MRglu best predicted the M-values (adjusted r2 = 0.85). In addition, SAT MRglu correlated with SAT glucose uptake ex vivo (r = 0.491). In different stages of the development of T2D, glucose uptake during hyperinsulinemia is elevated in the brain in parallel with an impairment in peripheral organs. Impaired glucose uptake in skeletal muscle and VAT together with elevated glucose uptake in brain were independently associated with whole-body insulin resistance, and these tissue-specific alterations may contribute to T2D development.
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| 3. |
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| 4. |
- Eriksson, Jan W, et al.
(författare)
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Tissue-specific glucose partitioning and fat content in prediabetes and type 2 diabetes: whole-body PET/MRI during hyperinsulinemia
- 2021
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Ingår i: European journal of endocrinology. - : Bioscientifica. - 0804-4643 .- 1479-683X. ; 184:6, s. 879-899
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To obtain direct quantifications of glucose turnover, volumes an d fat content of several tissues in the development of type 2 diabetes (T2D) using a novel integrated a pproach for whole-body imaging. Design and methods: Hyperinsulinemic-euglycemic clamps and simultaneous whole-body integrated [18F]FDG-PET/MRI with automated analyses were performed in control (n = 12), prediabetes (n = 16) and T2D (n = 13) subjects matched for age, sex and BMI. Results: Whole-body glucose uptake (Rd) was reduced by approximately 25% in T2D vs control subjects, and partitioning to brain was increased from 3.8% of total Rd in co ntrols to 7.1% in T2D. In liver, subcutaneous AT, thigh muscle, total tissue glucose metabolic rates (MRglu) and their % of total Rd were reduced in T2D compared to contr ol subjects. The prediabetes group had intermediate findings. Total MRglu in heart, visceral AT, gluteus and calf muscle was similar across groups. Whole-body insulin sensitivity asses sed as glucose infusion rate correlated with liver MR glu but inversely with brain MRglu. Liver fat content correlated with MRglu in brain but inversely with MRglu in other tissues. Calf muscle fat was inversely associated with MR glu only in the same muscle group. Conclusions: This integrated imaging approach provides detailed quantification of tissue-specific glucose metabolism. During T2D development, insulin-stimulated glucose disposal is impaired and increasingly shifted away from muscle, liver and fat toward the brain. Altered glucose handling in the brain and liver fat accumulation may aggravate insulin resistance in several organs. © 2021 BioScientifica Ltd.. All rights reserved.
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| 5. |
- Good, Elin, et al.
(författare)
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18Fluorodeoxyglucose uptake in relation to fat fraction and R2*in atherosclerotic plaques, using PET/MRI : a pilot study
- 2021
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Inflammation inside Atherosclerotic plaques represents a major pathophysiological process driving plaques towards rupture. Pre-clinical studies suggest a relationship between lipid rich necrotic core, intraplaque hemorrhage and inflammation, not previously explored in patients. Therefore, we designed a pilot study to investigate the feasibility of assessing the relationship between these plaque features in a quantitative manner using PET/MRI. In 12 patients with high-grade carotid stenosis the extent of lipid rich necrotic core and intraplaque hemorrhage was quantified from fat and R2* maps acquired with a previously validated 4-point Dixon MRI sequence in a stand-alone MRI. PET/MRI was used to measure 18F-FDG uptake. T1-weighted images from both scanners were used for registration of the quantitative Dixon data with the PET images. The plaques were heterogenous with respect to their volumes and composition. The mean values for the group were as follows: fat fraction (FF) 0.17% (± 0.07), R2* 47.6 s−1 (± 10.9) and target-to-blood pool ratio (TBR) 1.49 (± 0.48). At group level the correlation between TBR and FFmean was − 0.406, p 0.19 and for TBR and R2*mean 0.259, p 0.42. The lack of correlation persisted when analysed on a patient-by-patient basis but the study was not powered to draw definitive conclusions. We show the feasibility of analysing the quantitative relationship between lipid rich necrotic cores, intraplaque haemorrhage and plaque inflammation. The 18F-FDG uptake for most patients was low. This may reflect the biological complexity of the plaques and technical aspects inherent to 18F-FDG measurements.
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| 6. |
- Johansson, Emil, et al.
(författare)
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Whole-Body Imaging of Tissue-specific Insulin Sensitivity and Body Composition by Using an Integrated PET/MR System: A Feasibility Study
- 2018
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Ingår i: Radiology. - : Radiological Society of North America (RSNA). - 0033-8419 .- 1527-1315. ; 286:1, s. 271-278
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To develop, evaluate, and demonstrate the feasibility of a whole-body protocol for simultaneous assessment of tissue-specific insulin-mediated fluorine 18 (F-18) fluorodeoxyglucose (FDG) influx rates, tissue depots, and whole-body insulin sensitivity (referred to as the M value). Materials and Methods: An integrated positron emission tomography (PET)/magnetic resonance (MR) imaging system combined with hyperinsulinemic euglycemic clamp (HEC) was used. Dynamic whole-body PET imaging was used to determine the insulin-mediated F-18-FDG tissue influx rate (K-i) in the whole-body region by using the Patlak method. M value was determined with the HEC method at PET imaging. Tissue depots were quantified by using water-fat separated MR imaging and manual segmentations. Feasibility of the imaging protocol was demonstrated by using five healthy control participants and five patients with type 2 diabetes. Associations between M value and K-i were studied in multiple tissues by using the Pearson correlation. Results: Positive correlations were found between M value and K-i in multiple tissues: the gluteus muscle (r = 0.875; P = .001), thigh muscle (r = 0.903; P < .001), calf muscle (r = 0.825; P = .003), and abdominal visceral adipose tissue (r = 0.820; P = .004). A negative correlation was found in the brain (r = 0.798; P = .006). The MR imaging-based method for quantification of tissue depots was feasible for determining adipose tissue volumes and fat fractions. Conclusion: This PET/MR imaging protocol may be feasible for simultaneous assessment of tissue-specific insulin-mediated F-18-FDG influx rates, tissue depots, and M value. (C) RSNA, 2017
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| 7. |
- Kero, Tanja, et al.
(författare)
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Evaluation of quantitative CMR perfusion imaging by comparison with simultaneous 15O-water-PET
- 2021
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Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1071-3581 .- 1532-6551. ; 28, s. 1252-1266
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundWe assessed the quantitative accuracy of cardiac perfusion measurements using dynamic contrast-enhanced MRI with simultaneous 15O-water PET as reference with a fully integrated PET-MR scanner.Methods15 patients underwent simultaneous DCE MRI and 15O-water PET scans at rest and adenosine-stress on an integrated PET-MR scanner. Correlation and agreement between MRI- and PET-based global and regional MBF values were assessed using correlation and Bland–Altman analysis.ResultsThree subjects were excluded due to technical problems. Global mean (± SD) MBF values at rest and stress were 0.97 ± 0.27 and 3.19 ± 0.70 mL/g/min for MRI and 1.02 ± 0.28 and 3.13 ± 1.16 mL/g/min for PET (P = 0.66 and P = 0.81). The correlations between global and regional MRI- and PET-based MBF values were strong (r = 0.86 and r = 0.75). The biases were negligible for both global and regional MBF comparisons (0.01 and 0.00 mL/min/g for both), but the limits of agreement were wide for both global and regional MBF, with larger variability for high MBF-values.ConclusionThe correlation between simultaneous MBF measurements with DCE MRI and 15O-water PET measured in an integrated PET-MRI was strong but the agreement was only moderate indicating that MRI-based quantitative MBF measurements is not ready for clinical introduction.
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| 8. |
- Kvernby, Sofia, et al.
(författare)
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Quantitative comparison of data-driven gating and external hardware gating for 18F-FDG PET-MRI in patients with esophageal tumors
- 2021
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Ingår i: European Journal of Hybrid Imaging. - : Springer Nature. - 2510-3636. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundRespiratory motion during PET imaging reduces image quality. Data-driven gating (DDG) based on principal component analysis (PCA) can be used to identify respiratory signals. The use of DDG, without need for external devices, would greatly increase the feasibility of using respiratory gating in a routine clinical setting. The objective of this study was to evaluate data-driven gating in relation to external hardware gating and regular static image acquisition on PET-MRI data with respect to SUVmax and lesion volumes.MethodsSixteen patients with esophageal or gastroesophageal cancer (Siewert I and II) underwent a 6-min PET scan on a Signa PET-MRI system (GE Healthcare) 1.5-2 h after injection of 4 MBq/kg F-18-FDG. External hardware gating was done using a respiratory bellow device, and DDG was performed using MotionFree (GE Healthcare). The DDG raw data files and the external hardware-gating raw files were created on a Matlab-based toolbox from the whole 6-min scan LIST-file. For comparison, two 3-min static raw files were created for each patient. Images were reconstructed using TF-OSEM with resolution recovery with 2 iterations, 28 subsets, and 3-mm post filter. SUVmax and lesion volume were measured in all visible lesions, and noise level was measured in the liver. Paired t-test, linear regression, Pearson correlation, and Bland-Altman analysis were used to investigate difference, correlation, and agreement between the methods.ResultsA total number of 30 lesions were included in the study. No significant differences between DDG and external hardware-gating SUVmax or lesion volumes were found, but the noise level was significantly reduced in the DDG images. Both DDG and external hardware gating demonstrated significantly higher SUVmax (9.4% for DDG, 10.3% for external hardware gating) and smaller lesion volume (- 5.4% for DDG, - 6.6% for external gating) in comparison with non-gated static images.ConclusionsData-driven gating with MotionFree for PET-MRI performed similar to external device gating for esophageal lesions with respect to SUVmax and lesion volume. Both gating methods significantly increased the SUVmax and reduced the lesion volume in comparison with non-gated static acquisition. DDG resulted in reduced image noise compared to external device gating and static images.
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| 9. |
- Lundström, Elin, et al.
(författare)
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PET/MRI of glucose metabolic rate, lipid content and perfusion in human brown adipose tissue
- 2021
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the MRI-derived fat fraction (FF), from a Cooling-reheating protocol, for estimating the cold-induced brown adipose tissue (BAT) metabolic rate of glucose (MRglu) and changes in lipid content, perfusion and arterial blood volume (V-A) within cervical-supraclavicular fat (sBAT). Twelve volunteers underwent PET/MRI at baseline, during cold exposure and reheating. For each temperature condition, perfusion and V-A were quantified with dynamic [O-15]water-PET, and FF, with water-fat MRI. MRglu was assessed with dynamic [F-18]fluorodeoxyglucose-PET during cold exposure. sBAT was defined using anatomical criteria, and its subregion sBAT(HI), by MRglu>11 mu mol/100 cm(3)/min. For all temperature conditions, sBAT-FF correlated negatively with sBAT-MRglu (rho <=- 0.87). After 3 h of cold, sBAT-FF decreased (- 2.13 percentage points) but tended to normalize during reheating although sBAT(HI)-FF remained low. sBAT-perfusion and sBAT-V-A increased during cold exposure (perfusion:+5.2 ml/100 cm(3)/min, V-A:+4.0 ml/100 cm(3)). sBAT-perfusion remained elevated and sBAT-V-A normalized during reheating. Regardless of temperature condition during the Cooling-reheating protocol, sBAT-FF could predict the cold-induced sBAT-MRglu. The FF decreases observed after reheating were mainly due to lipid consumption, but could potentially be underestimated due to intracellular lipid replenishment. The influence of perfusion and V-A, on the changes in FF observed during cold exposure, could not be ruled out.
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| 10. |
- Rosqvist, Fredrik, 1985-, et al.
(författare)
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Overeating saturated fat promotes fatty liver and ceramides compared to polyunsaturated fat : a randomized trial
- 2019
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Oxford University Press. - 0021-972X .- 1945-7197. ; 104:12, s. 6207-6219
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Saturated fat (SFA) versus polyunsaturated fat (PUFA) may promote non-alcoholic fatty liver disease (NAFLD) by yet unclear mechanisms.OBJECTIVE: To investigate if overeating SFA- and PUFA-enriched diets lead to differential liver fat accumulation in overweight and obese humans.DESIGN: Double-blind randomized trial (LIPOGAIN-2). Overfeeding SFA vs PUFA for 8 weeks, followed by 4 weeks of caloric restriction.SETTING: General community.Participants: n=61 overweight or obese men and women.INTERVENTION: Muffins high in either palm (SFA)- or sunflower oil (PUFA) were added to the habitual diet.MAIN OUTCOME MEASURE: Lean tissue mass (not reported here). Secondary and exploratory outcomes included liver and ectopic fat depots.RESULTS: By design, body weight gain was similar in SFA (2.31±1.38 kg) and PUFA (2.01±1.90 kg) groups, P=0.50. SFA markedly induced liver fat content (50% relative increase) along with liver enzymes and atherogenic serum lipids. In contrast, despite similar weight gain, PUFA did not increase liver fat or liver enzymes or cause any adverse effects on blood lipids. SFA had no differential effect on the accumulation of visceral fat, pancreas fat or total body fat compared with PUFA. SFA consistently increased, while PUFA reduced circulating ceramides; changes that were moderately associated with liver fat changes and proposed markers of hepatic lipogenesis. The adverse metabolic effects of SFA were reversed by calorie restriction.CONCLUSIONS: Saturated fat markedly induces liver fat and serum ceramides whereas dietary polyunsaturated fat prevent liver fat accumulation, reduce ceramides and hyperlipidemia during excess energy intake and weight gain in overweight individuals.
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