| 1. |
- Linge, Jennifer, et al.
(författare)
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Sub-phenotyping Metabolic Disorders Using Body Composition : An Individualized, Nonparametric Approach Utilizing Large Data Sets
- 2019
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Ingår i: Obesity. - : John Wiley & Sons. - 1930-7381 .- 1930-739X. ; 27:7, s. 1190-1199
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study performed individual-centric, data-driven calculations of propensity for coronary heart disease (CHD) and type 2 diabetes (T2D), utilizing magnetic resonance imaging-acquired body composition measurements, for sub-phenotyping of obesity and nonalcoholic fatty liver disease (NAFLD).Methods: A total of 10,019 participants from the UK Biobank imaging substudy were included and analyzed for visceral and abdominal subcutaneous adipose tissue, muscle fat infiltration, and liver fat. An adaption of the k-nearest neighbors algorithm was applied to the imaging variable space to calculate individualized CHD and T2D propensity and explore metabolic sub-phenotyping within obesity and NAFLD.Results: The ranges of CHD and T2D propensity for the whole cohort were 1.3% to 58.0% and 0.6% to 42.0%, respectively. The diagnostic performance, area under the receiver operating characteristic curve (95% CI), using disease propensities for CHD and T2D detection was 0.75 (0.73-0.77) and 0.79 (0.77-0.81). Exploring individualized disease propensity, CHD phenotypes, T2D phenotypes, comorbid phenotypes, and metabolically healthy phenotypes were found within obesity and NAFLD.Conclusions: The adaptive k-nearest neighbors algorithm allowed an individual-centric assessment of each individual’s metabolic phenotype moving beyond discrete categorizations of body composition. Within obesity and NAFLD, this may help in identifying which comorbidities a patient may develop and conse- quently enable optimization of treatment.
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| 2. |
- Romu, Thobias, et al.
(författare)
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A randomized trial of cold-exposure on energy expenditure and supraclavicular brown adipose tissue volume in humans
- 2016
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Ingår i: Metabolism-Clinical and Experimental. - : Elsevier BV. - 0026-0495 .- 1532-8600. ; 65:6, s. 926-934
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To study if repeated cold-exposure increases metabolic rate and/or brown adipose tissue (BAT) volume in humans when compared with avoiding to freeze. Design. Randomized, open, parallel-group trial. Methods. Healthy non-selected participants were randomized to achieve cold-exposure 1 hour/day, or to avoid any sense of feeling cold, for 6 weeks. Metabolic rate (MR) was measured by indirect calorimetry before and after acute cold-exposure with cold vests and ingestion of cold water. The BAT volumes in the supraclavicular region were measured with magnetic resonance imaging (MRI). Results. Twenty-eight participants were recruited, 12 were allocated to controls and 16 to cold-exposure. Two participants in the cold group dropped out and one was excluded. Both the non-stimulated and the cold-stimulated MR were lowered within the group randomized to avoid cold (MR at room temperature from 1841 +/- 199 kCal/24 h to 1795 +/- 213 kCal/24 h, p = 0.047 cold-activated MR from 1900 +/- 150 kCal/24 h to 1793 +/- 215 kCal/24 h, p = 0.028). There was a trend towards increased MR at room temperature following the intervention in the cold-group (p = 0.052). The difference between MR changes by the interventions between groups was statistically significant (p = 0.008 at room temperature, p = 0.032 after cold-activation). In an on-treatment analysis after exclusion of two participants that reported >= 8 days without cold-exposure, supraclavicular BAT volume had increased in the cold-exposure group (from 0.0175 +/- 0.015 1 to 0.0216 +/- 0.014 1, p = 0.049). Conclusions. We found evidence for plasticity in metabolic rate by avoiding to freeze compared with cold-exposure in a randomized setting in non-selected humans.
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| 3. |
- Romu, Thobias, et al.
(författare)
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Characterization of Brown Adipose Tissue by Water-Fat Separated Magnetic Resonance Imaging
- 2015
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 42:6, s. 1639-1645
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Tidskriftsartikel (refereegranskat)abstract
- Background: To evaluate the possibility of quantifying brown adipose tissue (BAT) volume and fat concentration with a high resolution, long echo time, dual-echo Dixon imaging protocol. Methods: A 0.42 mm isotropic resolution water-fat separated MRI protocol was implemented by using the second opposite-phase echo and third in-phase echo. Fat images were calibrated with regard to the intensity of nearby white adipose tissue (WAT) to form relative fat content (RFC) images. To evaluate the ability to measure BAT volume and RFC contrast dynamics, rats were divided into two groups that were kept at 48 or 22 degrees C for 5 days. The rats were then scanned in a 70 cm bore 3.0 Tesla MRI scanner and a human dual energy CT. Interscapular, paraaortal, and perirenal BAT (i/pa/pr-BAT) depots as well as WAT and muscle were segmented in the MRI and CT images. Biopsies were collected from the identified BAT depots. Results: The biopsies confirmed that the three depots identified with the RFC images consisted of BAT. There was a significant linear correlation (P< 0.001) between the measured RFC and the Hounsfield units from DECT. Significantly lower iBAT RFC (P=0.0064) and significantly larger iBAT and prBAT volumes (P=0.0017) were observed in the cold stimulated rats. Conclusion: The calibrated Dixon images with RFC scaling can depict BAT and be used to measure differences in volume, and fat concentration, induced by cold stimulation. The high correlation between RFC and HU suggests that the fat concentration is the main RFC image contrast mechanism.
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| 4. |
- Morales Drissi, Natasha, et al.
(författare)
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Unexpected Fat Distribution in Adolescents With Narcolepsy
- 2018
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Ingår i: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Narcolepsy type 1 is a chronic sleep disorder with significantly higher BMI reported in more than 50% of adolescent patients, putting them at a higher risk for metabolic syndrome in adulthood. Although well-documented, the body fat distribution and mechanisms behind weight gain in narcolepsy are still not fully understood but may be related to the loss of orexin associated with the disease. Orexin has been linked to the regulation of brown adipose tissue (BAT), a metabolically active fat involved in energy homeostasis. Previous studies have used BMI and waist circumference to characterize adipose tissue increases in narcolepsy but none have investigated its specific distribution. Here, we examine adipose tissue distribution in 19 adolescent patients with narcolepsy type 1 and compare them to 17 of their healthy peers using full body magnetic resonance imaging (MRI). In line with previous findings we saw that the narcolepsy patients had more overall fat than the healthy controls, but contrary to our expectations there were no group differences in supraclavicular BAT, suggesting that orexin may have no effect at all on BAT, at least under thermoneutral conditions. Also, in line with previous reports, we observed that patients had more total abdominal adipose tissue (TAAT), however, we found that they had a lower ratio between visceral adipose tissue (VAT) and TAAT indicating a relative increase of subcutaneous abdominal adipose tissue (ASAT). This relationship between VAT and ASAT has been associated with a lower risk for metabolic disease. We conclude that while weight gain in adolescents with narcolepsy matches that of central obesity, the lower VAT ratio may suggest a lower risk of developing metabolic disease.
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| 5. |
- Petridou, Elia, et al.
(författare)
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Breast fat volume measurement in a wide-bore 3T MR: comparison of traditional mammographic density evaluation with MR density measurements using automatic segmentation.
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Aims and objectivesVariations in breast density in imaging are caused by varying proportions of fat and fibro-glandular tissue. Breast density is an independent marker of breast cancer risk and therefore a number of techniques have been developed to measure breast density using different imaging modalities. The aim of this research was to compare a fully automated technique of producing volumetric measurements of fat and fibroglandular breast tissue from segmented magnetic resonance imaging (MRI) and to compare with the well-established, observer-dependent Breast Imaging Reporting and Data Systems (BI-RADS) density classification using mammography.Methods and materialsThis was a prospective inter-method comparison study. The study design was a prospective analysis of volumetric breast density obtained from breast MRI scans compared with mammographic breast density using BIRADS. Ethical approval for the study was obtained from the local Research Ethics Committee. 40 women undergoing mammography and dynamic breast MRI as part of their clinical management were recruited. Fat-water separated MR images derived from a 2 point Dixon technique using phase-sensitive reconstruction and atlas based segmentation were obtained before and after the administration of intravenous gadolinium. Breast density, which was defined the proportion of breast fat subtracted from the total volume of the breast, was assessed using proprietary software (Advanced MR Analytics (AMRA), Linköping, Sweden). The method was previously described and first used for measurement of abdominal fat.The results were compared to the widely used four-quartile quantitative BIRADS scale undertaken by two experienced breast radiologists. ResultsThe mean unenhanced breast percentage of fibro-glandular tissue measured on MRI was 0.31 ± 0.22 (mean ± SD) for the left and 0.29 ± 0.21 for the right. The mean density on the contrast-enhanced images was 0.32 ± 0.19 for the left and 0.32 ± 0.2 for right. There was "almost perfect" correlation between the quantification pre and post-contrast breast fibro- glandular tissue quantification: Spearman correlation rho=0.98 (95% confidence intervals (CI): 0.97-0.99) for the left and rho=0.99 (CI: 0.98-0.99) for the right.For each of the BIRADS scores 1-4 observer 1 scored a total number of breasts as n=2,35,26,15 (total 80) and observer 2 scored n=4,25,45,16 respectively. Correlation between BIRADS scores and automated MRI breast density was significant for both operators, Spearman Correlation coefficient rho=0.75. ConclusionAutomated breast fat density measurement using MR correlates strongly with the current mammographic standard BIRADS. Results for percentage fibro-glandular component on unenhanced breast MR correlate very closely with post-contrast MR. Breast density measurements derived from automated segmentation of unenhanced breast MRI could be used instead of mammographic measurements for assessing breast cancer risk.
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| 6. |
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| 7. |
- Gharehbaghi, Arash, et al.
(författare)
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A novel method for discrimination between innocent and pathological heart murmurs
- 2015
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Ingår i: Medical Engineering and Physics. - : Elsevier. - 1350-4533 .- 1873-4030. ; 37:7, s. 674-682
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel method for discrimination between innocent and pathological murmurs using the growing time support vector machine (GTSVM). The proposed method is tailored for characterizing innocent murmurs (IM) by putting more emphasis on the early parts of the signal as IMs are often heard in early systolic phase. Individuals with mild to severe aortic stenosis (AS) and IM are the two groups subjected to analysis, taking the normal individuals with no murmur (NM) as the control group. The AS is selected due to the similarity of its murmur to IM, particularly in mild cases. To investigate the effect of the growing time windows, the performance of the GTSVM is compared to that of a conventional support vector machine (SVM), using repeated random sub-sampling method. The mean value of the classification rate/sensitivity is found to be 88%/86% for the GTSVM and 84%/83% for the SVM. The statistical evaluations show that the GTSVM significantly improves performance of the classification as compared to the SVM.
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| 8. |
- Abrahamsson, Annelie, et al.
(författare)
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Dense breast tissue in postmenopausal women is associated with a pro-inflammatory microenvironment in vivo
- 2016
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Ingår i: Oncoimmunology. - : TAYLOR & FRANCIS INC. - 2162-4011 .- 2162-402X. ; 5:10
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Tidskriftsartikel (refereegranskat)abstract
- Inflammation is one of the hallmarks of carcinogenesis. High mammographic density has been associated with increased risk of breast cancer but the mechanisms behind are poorly understood. We evaluated whether breasts with different mammographic densities exhibited differences in the inflammatory microenvironment.Postmenopausal women attending the mammography-screening program were assessed having extreme dense, n = 20, or entirely fatty breasts (nondense), n = 19, on their regular mammograms. Thereafter, the women were invited for magnetic resonance imaging (MRI), microdialysis for the collection of extracellular molecules in situ and a core tissue biopsy for research purposes. On the MRI, lean tissue fraction (LTF) was calculated for a continuous measurement of breast density. LTF confirmed the selection from the mammograms and gave a continuous measurement of breast density. Microdialysis revealed significantly increased extracellular in vivo levels of IL-6, IL-8, vascular endothelial growth factor, and CCL5 in dense breast tissue as compared with nondense breasts. Moreover, the ratio IL-1Ra/IL-1 was decreased in dense breasts. No differences were found in levels of IL-1, IL-1Ra, CCL2, leptin, adiponectin, or leptin:adiponectin ratio between the two breast tissue types. Significant positive correlations between LTF and the pro-inflammatory cytokines as well as between the cytokines were detected. Stainings of the core biopsies exhibited increased levels of immune cells in dense breast tissue.Our data show that dense breast tissue in postmenopausal women is associated with a pro-inflammatory microenvironment and, if confirmed in a larger cohort, suggests novel targets for prevention therapies for women with dense breast tissue.
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| 9. |
- Agebratt, Christian, et al.
(författare)
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A Randomized Study of the Effects of Additional Fruit and Nuts Consumption on Hepatic Fat Content, Cardiovascular Risk Factors and Basal Metabolic Rate
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:1, s. e0147149-
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundFruit has since long been advocated as a healthy source of many nutrients, however, the high content of sugars in fruit might be a concern.ObjectivesTo study effects of an increased fruit intake compared with similar amount of extra calories from nuts in humans.MethodsThirty healthy non-obese participants were randomized to either supplement the diet with fruits or nuts, each at +7 kcal/kg bodyweight/day for two months. Major endpoints were change of hepatic fat content (HFC, by magnetic resonance imaging, MRI), basal metabolic rate (BMR, with indirect calorimetry) and cardiovascular risk markers.ResultsWeight gain was numerically similar in both groups although only statistically significant in the group randomized to nuts (fruit: from 22.15±1.61 kg/m2 to 22.30±1.7 kg/m2, p = 0.24 nuts: from 22.54±2.26 kg/m2 to 22.73±2.28 kg/m2, p = 0.045). On the other hand BMR increased in the nut group only (p = 0.028). Only the nut group reported a net increase of calories (from 2519±721 kcal/day to 2763±595 kcal/day, p = 0.035) according to 3-day food registrations. Despite an almost three-fold reported increased fructose-intake in the fruit group (from 9.1±6.0 gram/day to 25.6±9.6 gram/day, p<0.0001, nuts: from 12.4±5.7 gram/day to 6.5±5.3 gram/day, p = 0.007) there was no change of HFC. The numerical increase in fasting insulin was statistical significant only in the fruit group (from 7.73±3.1 pmol/l to 8.81±2.9 pmol/l, p = 0.018, nuts: from 7.29±2.9 pmol/l to 8.62±3.0 pmol/l, p = 0.14). Levels of vitamin C increased in both groups while α-tocopherol/cholesterol-ratio increased only in the fruit group.ConclusionsAlthough BMR increased in the nut-group only this was not linked with differences in weight gain between groups which potentially could be explained by the lack of reported net caloric increase in the fruit group. In healthy non-obese individuals an increased fruit intake seems safe from cardiovascular risk perspective, including measurement of HFC by MRI.
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| 10. |
- Andersson, Thord, et al.
(författare)
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Consistent intensity inhomogeneity correction in water-fat MRI
- 2015
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley-Blackwell. - 1053-1807 .- 1522-2586. ; 42:2
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To quantitatively and qualitatively evaluate the water-signal performance of the consistent intensity inhomogeneity correction (CIIC) method to correct for intensity inhomogeneitiesMETHODS: Water-fat volumes were acquired using 1.5 Tesla (T) and 3.0T symmetrically sampled 2-point Dixon three-dimensional MRI. Two datasets: (i) 10 muscle tissue regions of interest (ROIs) from 10 subjects acquired with both 1.5T and 3.0T whole-body MRI. (ii) Seven liver tissue ROIs from 36 patients imaged using 1.5T MRI at six time points after Gd-EOB-DTPA injection. The performance of CIIC was evaluated quantitatively by analyzing its impact on the dispersion and bias of the water image ROI intensities, and qualitatively using side-by-side image comparisons.RESULTS: CIIC significantly ( P1.5T≤2.3×10-4,P3.0T≤1.0×10-6) decreased the nonphysiological intensity variance while preserving the average intensity levels. The side-by-side comparisons showed improved intensity consistency ( Pint≤10-6) while not introducing artifacts ( Part=0.024) nor changed appearances ( Papp≤10-6).CONCLUSION: CIIC improves the spatiotemporal intensity consistency in regions of a homogenous tissue type.
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