| 1. |
- Lidell, Martin, 1970, et al.
(författare)
-
Evidence for two types of brown adipose tissue in humans
- 2013
-
Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 19:5, s. 631-634
-
Tidskriftsartikel (refereegranskat)abstract
- The previously observed supraclavicular depot of brown adipose tissue (BAT) in adult humans was
|
|
| 2. |
- Linge, Jennifer, et al.
(författare)
-
Sub-phenotyping Metabolic Disorders Using Body Composition : An Individualized, Nonparametric Approach Utilizing Large Data Sets
- 2019
-
Ingår i: Obesity. - : John Wiley & Sons. - 1930-7381 .- 1930-739X. ; 27:7, s. 1190-1199
-
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.
|
|
| 3. |
- Tejani, Sanaa, et al.
(författare)
-
Cardiometabolic Health Outcomes Associated With Discordant Visceral and Liver Fat Phenotypes: Insights From the Dallas Heart Study and UK Biobank
- 2022
-
Ingår i: Mayo Clinic proceedings. - New York, United States : Elsevier. - 0025-6196 .- 1942-5546. ; 97:2, s. 225-237
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: To evaluate the cardiometabolic outcomes associated with discordant visceral adipose tissue (VAT) and liver fat (LF) phenotypes in 2 cohorts.Patients and Methods: Participants in the Dallas Heart Study underwent baseline imaging from January 1, 2000, through December 31, 2002, and were followed for incident cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM) through 2013. Associations between VAT-LF groups (low-low, high-low, low-high, and high-high) and outcomes were assessed using multivariable- adjusted regression and were replicated in the independent UK Biobank.Results: The Dallas Heart Study included 2064 participants (mean SD age, 449 years; 54% female; 47% black). High VATehigh LF and high VATelow LF were associated with prevalent atheroscle- rosis, whereas low VATehigh LF was not. Of 1731 participants without CVD/T2DM, 128 (7.4%) developed CVD and 95 (5.5%) T2DM over a median of 12 years. High VATehigh LF and high VATelow LF were associated with increased risk of CVD (hazard ratios [HRs], 2.0 [95% CI, 1.3 to 3.2] and 2.4 [95% CI, 1.4 to 4.1], respectively) and T2DM (odds ratios [ORs], 7.8 [95% CI, 3.8 to 15.8] and 3.3 [95% CI, 1.4 to 7.8], respectively), whereas low VATehigh LF was associated with T2DM (OR, 2.7 [95% CI, 1.1 to 6.7]). In the UK Biobank (N1⁄422,354; April 2014-May 2020), only high VATelow LF remained associated with CVD after multivariable adjustment for age and body mass index (HR, 1.5 [95% CI, 1.2 to 1.9]).Conclusion: Although VAT and LF are each associated with cardiometabolic risk, these observations demonstrate the importance of separating their cardiometabolic implications when there is presence or absence of either or both in an individual.
|
|
| 4. |
|
|
| 5. |
- Romu, Thobias, et al.
(författare)
-
MANA - Multi scale adaptive normalized averaging
- 2011
-
Ingår i: 2011 IEEE International Symposium on Biomedical Imaging: From Nano to Macro. - : IEEE conference proceedings. - 9781424441280 ; , s. 361-364
-
Konferensbidrag (refereegranskat)abstract
- It is possible to correct intensity inhomogeneity in fat–water Magnetic Resonance Imaging (MRI) by estimating a bias field based on the observed intensities of voxels classified as the pure adipose tissue. The same procedure can also be used to quantify fat volume and its distribution which opens up for new medical applications. The bias field estimation method has to be robust since pure fat voxels are irregularly located and the density varies greatly within and between image volumes. This paper introduces Multi scale Adaptive Normalized Average (MANA) that solves this problem bybasing the estimate on a scale space of weighted averages. By usingthe local certainty of the data MANA preserves details where the local data certainty is high and provides realistic values in sparse areas.
|
|
| 6. |
- Romu, Thobias, et al.
(författare)
-
Characterization of Brown Adipose Tissue by Water-Fat Separated Magnetic Resonance Imaging
- 2015
-
Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 42:6, s. 1639-1645
-
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.
|
|
| 7. |
- Olsson, Erik, 1960, et al.
(författare)
-
Hippocampal volumes in patients exposed to low-dose radiation to the basal brain. A case--control study in long-term survivors from cancer in the head and neck region.
- 2012
-
Ingår i: Radiation oncology (London, England). - 1748-717X. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: BACKGROUND: An earlier study from our group of long time survivors of head and neck cancer who had received a low radiation dose to the hypothalamic-pituitary region, with no signs of recurrence or pituitary dysfunction, had their quality of life (QoL) compromised as compared with matched healthy controls. Hippocampal changes have been shown to accompany several psychiatric conditions and the aim of the present study was to test whether the patients' lowered QoL was coupled to a reduction in hippocampal volume. METHODS: Patients (11 men and 4 women, age 31--65) treated for head and neck cancer 4--10 years earlier and with no sign of recurrence or pituitary dysfunction, and 15 matched controls were included. The estimated radiation doses to the basal brain including the hippocampus (1.5 -- 9.3 Gy) had been calculated in the earlier study. The hippocampal volumetry was done on coronal sections from a 1.5 T MRI scanner. Measurements were done by two independent raters, blinded to patients and controls, using a custom method for computer assisted manual segmentation. The volumes were normalized for intracranial volume which was also measured manually. The paired t test and Wilcoxon's signed rank test were used for the main statistical analysis. RESULTS: There was no significant difference with respect to left, right or total hippocampal volume between patients and controls. All mean differences were close to zero, and the two-tailed 95% confidence interval for the difference in total, normalized volume does not include a larger than 8% deficit in the patients. CONCLUSION: The study gives solid evidence against the hypothesis that the patients' lowered quality of life was due to a major reduction of hippocampal volume.
|
|
| 8. |
- Petridou, Elia, et al.
(författare)
-
Breast fat volume measurement in a wide-bore 3T MR: comparison of traditional mammographic density evaluation with MR density measurements using automatic segmentation.
- 2015
-
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.
|
|
| 9. |
- Eckerström, Carl, et al.
(författare)
-
Small baseline volume of left hippocampus is associated with subsequent conversion of MCI into dementia. The Göteborg MCI study.
- 2008
-
Ingår i: Journal of the Neurological Sciences. - : Elsevier BV. - 0022-510X .- 1878-5883. ; 272:1-2, s. 48-59
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Earlier studies have reported that hippocampal atrophy can to some extent predict which patients with mild cognitive impairment (MCI) will subsequently convert to dementia, and that converters have an enhanced rate of hippocampal volume loss. Objective: To further validate the hypothesis that hippocampal atrophy predicts conversion from MCI to dementia, to relate baseline hippocampal volume to different forms of dementia, and to investigate the role of hippocampal side differences and rate of volume loss over time. Patients: The subjects (N = 68) include patients with MCI at baseline and progression to dementia at the two-year follow-up (N = 21), stable MCI patients (N = 21), and controls (N = 26). Among the progressing patients, 13 were diagnosed as having AD. Methods: The Göteborg MCI study is a clinically based longitudinal study with biannual clinical assessments. Hippocampal volumetry was performed manually on the MRI investigations at baseline and at the two-year follow-up. Results: Hippocampal volumetry could predict conversion to dementia in both the AD and the non-AD subgroup of converters. Left hippocampal volume in particular discriminated between converting and stable MCI. Cut off points for individual discrimination were shown to be potentially useful. The converting MCI group had a significantly higher rate of hippocampal volume loss as compared to the stable MCI group. Conclusions: In MCI patients, hippocampal volumetry at baseline gives prognostic information about possible development of AD and non-AD dementia. Contrary to earlier studies, we found that left hippocampal volume has the best predictive power. Reliable predictions appear to be possible in many individual cases.
|
|
| 10. |
- Moreno, Rodrigo, et al.
(författare)
-
Soft classification of trabeculae in trabecular bone
- 2011
-
Ingår i: Biomedical Imaging: From Nano to Macro, 2011. - : IEEE. - 9781424441273 ; , s. 1641-1644
-
Konferensbidrag (refereegranskat)abstract
- Classification of trabecular bone aims at discriminating different types of trabeculae. This paper proposes a method to perform a soft classification from binary 3D images. In a first step, the local structure tensor is used to estimate a membership degree of every voxel to three different classes, plate-, rod- and junction-like trabeculae. In a second step, the global structure tensor of plate-like trabeculae is compared with the local orientation of rod-like trabeculae in order to discriminate aligned from non-aligned rods. Results show that soft classification can be used for estimating independent parameters of trabecular bone for every different class, by using the classification as a weighting function.
|
|
