John Brandberg

Whole-body adipose tissue analysis : Comparison of MRI, CT and dual energy X-ray absorptiometry

The aim of this study was to validate a recently proposed MRI-based T(1)-mapping method for analysis of whole-body adipose tissue (AT) using an established CT protocol as reference and to include results from dual energy X-ray absorptiometry (DEXA). 10 subjects, drawn from the Swedish Obese Subjects Sibling-pairs study, were examined using CT, MRI and DEXA. The CT analysis was based on 28 imaged slices. T(1) maps were calculated using contiguous MRI data from two different gradient echo sequences acquired using different flip angles. CT and MRI comparison was performed slice-wise and for the whole-body region. Fat weights were compared between all three modalities. Strong correlations (r > or = 0.977, p<0.0001) were found between MRI and CT whole-body and AT volumes. MRI visceral AT volume was underestimated by 0.79 +/- 0.75 l (p = 0.005), but total AT was not significantly different from that estimated by CT (MRI - CT = -0.61+/-1.17 l; p = 0.114). DEXA underestimated fat weights by 5.23 +/- 1.71 kg (p = 0.005) compared with CT. MRI underestimated whole-body volume by 2.03 +/- 1.61 l (p = 0.005) compared with CT. Weights estimated either by CT or by DEXA were not significantly different from weights measured using scales. In conclusion, strong correlations were found between whole-body AT results from CT, MRI-based T(1) mapping and DEXA. If the differences between the results from T(1)-mapping and CT-based analysis are accepted, the T(1)-mapping method allows fully automated post-processing of whole-body MRI data, allowing longitudinal whole-body studies that are also applicable for children and adolescents.

Serum Phospholipid Fatty Acids, Adipose Tissue, and Metabolic Markers in Obese Adolescents

Objective: Fatty acid (FA) composition has a role in adipogenesis. The objective was to study serum phospholipid (PL) FAs in adolescents and their relation to abdominal adipose tissue (AT) compartments and metabolic markers.

Pubertal Timing Is an Independent Predictor of Central Adiposity in Young Adult Males: The Gothenburg Osteoporosis and Obesity Determinants Study

The role of puberty and normal variations in pubertal timing for the development of obesity in men is unclear. The aim of the current study was to investigate the impact of pubertal timing and prepubertal BMI (kg/m2) for young adult BMI and fat mass distribution. Detailed growth charts from birth to age 18–20 years were retrieved for the men participating in the population-based Gothenburg Osteoporosis and Obesity Determinants study. Age at peak height velocity (PHV) and BMI at age 10 years were estimated for 579 subjects, and PHV was used as an assessment of pubertal timing. The fat mass characterization and distribution were analyzed using dual X-ray absorptiometry and peripheral as well as abdominal computed tomography at age 18.9 ± 0.5 years. We demonstrate that age at PHV is an independent negative predictor of young adult BMI and whole-body fat mass. Interestingly, age at PHV is an independent negative predictor of central, but not peripheral, fat mass. In contrast, BMI at 10 years of age predicts both central and peripheral subcutaneous fat mass. In conclusion, we demonstrate that early pubertal onset specifically predicts a central fat mass distribution, while a predominantly subcutaneous obese phenotype is strongly predicted by a high prepubertal BMI.

The Swedish CArdioPulmonary BioImage Study: objectives and design.

Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large‐scale ‘omics’ and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started.

BMI changes during childhood and adolescence as predictors of amount of adult subcutaneous and visceral adipose tissue in men: the GOOD Study.

OBJECTIVE The amount of visceral adipose tissue is a risk factor for the metabolic syndrome. It is unclear how BMI changes during childhood and adolescence predict adult fat distribution. We hypothesized that there are critical periods during development for the prediction of adult subcutaneous and visceral fat mass by BMI changes during childhood and adolescence. RESEARCH DESIGN AND METHODS Detailed growth charts were retrieved for the men participating in the population-based Gothenburg Osteoporosis and Obesity Determinants (GOOD) Study (n = 612). Body composition was analyzed using dual-energy X-ray absorptiometry and adipose tissue areas using abdominal computed tomography at 18 to 20 years of age. RESULTS The main finding in the present study was that subjects with increases in BMI Z score of more than 1 SD during adolescence had, independent of prepubertal BMI, both larger subcutaneous (+138%; P < 0.001) and visceral adipose tissue areas (+91%; P < 0.001) than subjects with unchanged BMI Z-score. In contrast, subjects with increases in BMI Z score of more than 1 SD during late childhood had a larger amount of adult subcutaneous adipose tissue (+83%; P < 0.001) than subjects with unchanged BMI Z score but an unaffected amount of visceral adipose tissue. BMI changes during adolescence predict both visceral and subcutaneous adipose tissue of the abdomen, whereas BMI changes during late childhood predict only the subcutaneous adipose tissue. CONCLUSIONS The amount of visceral adipose tissue in young adult men was associated with BMI changes specifically during adolescence, whereas the amount of subcutaneous adipose tissue was associated with BMI changes during both late childhood and adolescence.

Whole-body T1 mapping improves the definition of adipose tissue: consequences for automated image analysis.

To determine whether a whole‐body T1‐mapping acquisition method improves the definition of adipose tissue (AT) and simplifies automated AT segmentation compared to an image‐based method.

Automated analysis of liver fat, muscle and adipose tissue distribution from CT suitable for large-scale studies

Computed Tomography (CT) allows detailed studies of body composition and its association with metabolic and cardiovascular disease. The purpose of this work was to develop and validate automated and manual image processing techniques for detailed and efficient analysis of body composition from CT data. The study comprised 107 subjects examined in the Swedish CArdioPulmonary BioImage Study (SCAPIS) using a 3-slice CT protocol covering liver, abdomen, and thighs. Algorithms were developed for automated assessment of liver attenuation, visceral (VAT) and subcutaneous (SAT) abdominal adipose tissue, thigh muscles, subcutaneous, subfascial (SFAT) and intermuscular adipose tissue. These were validated using manual reference measurements. SFAT was studied in selected subjects were the fascia lata could be visually identified (approx. 5%). In addition, precision of manual measurements of intra- (IPAT) and retroperitoneal adipose tissue (RPAT) and deep- and superficial SAT was evaluated using repeated measurements. Automated measurements correlated strongly to manual reference measurements. The SFAT depot showed the weakest correlation (r = 0.744). Automated VAT and SAT measurements were slightly, but significantly overestimated (≤4.6%, p ≤ 0.001). Manual segmentation of abdominal sub-depots showed high repeatability (CV ≤ 8.1%, r ≥ 0.930). We conclude that the low dose CT-scanning and automated analysis makes the setup suitable for large-scale studies.

The reduction in visceral fat mass in response to growth hormone is more marked in men than in oestrogen-deficient women

CONTEXT Women with severe growth hormone (GH) deficiency have a less marked response to GH replacement than men. This has mostly been attributed to the attenuating effects of oestrogen replacement therapy. OBJECTIVE To study gender related differences in the response to GH treatment in men and postmenopausal women. METHODS Fifteen men and 15 age- and BMI-matched women with abdominal obesity (mean age: 58; range 51-64 years) were treated for one year with similar doses (0.47 vs. 0.51 mg/day) of GH. All women were postmenopausal not receiving oestrogen treatment. Insulin sensitivity was assessed using a hyperinsulinemic euglycemic clamp and body composition by computed tomography (CT) scans and from total body potassium, K(40). RESULTS Men and women were comparable at baseline in terms of waist circumference, IGF-1 and lipid levels. After one year of GH treatment, there was a 18% reduction in visceral adipose tissue (VAT) in men and a 5% reduction in women (P=0.0001 men vs. women). Although the magnitude of the difference was small, men increased more in thigh muscle mass (P<0.0001 vs. women). A reduction in thigh intermuscular adipose tissue (IMAT) and diastolic blood pressure was seen only in men (both p<0.05 vs. baseline). A decrease in LDL cholesterol, and an increase in serum insulin, was observed only in women (both p<0.05 vs. baseline). CONCLUSION Low dose GH treatment reduced VAT more markedly in men as compared with women. As all women were postmenopausal and oestrogen-deficient, this gender difference in responsiveness was not due to an antagonistic effect of oestrogen on peripheral GH action.

Accurate tissue area measurements with considerably reduced radiation dose achieved by patient-specific CT scan parameters

A low-dose technique was compared with a standard diagnostic technique for measuring areas of adipose and muscle tissue and CT numbers for muscles in a body composition application. The low-dose technique was intended to keep the expected deviation in the measured area of adipose and muscle tissue to <1% of the total tissue area. The largest diameter of the patient determined the parameters for the low-dose technique. 17 patients - chosen to cover a wide range of diameters (31-47 cm) for both abdomen and thighs - were examined using both techniques. Tissue areas were compared, as were CT numbers for muscle tissue. Image noise was quantified by standard deviation measurements. The area deviation was <1%, except in the smallest subjects, in whom it was <2%. The integral radiation dose of the low-dose technique was reduced to 2-3% for diameters of 31-35 cm and to 7.5-50% for diameters of 36-47 cm as compared with the integral dose by the standard diagnostic technique. The CT numbers of muscle tissue remained unchanged with reduced radiation dose. Image noise was on average 20.9 HU (Hounsfield units) for subjects with diameters of 31-35 cm and 11.2 HU for subjects with diameters in the range of 36-47 cm. In conclusion, for body composition studies with CT, scan protocols can be adjusted so that the integral dose is lowered to 2-60% of the standard diagnostic technique at our centre without adversely altering area measurements of adipose and muscle tissue and without altering CT numbers of muscle tissue.

Absolute lung size and the sex difference in breathlessness in the general population

Background Breathlessness is associated with major adverse health outcomes and is twice as common in women as men in the general population. We evaluated whether this is related to their lower absolute lung volumes. Methods Cross-sectional analysis of the population-based Swedish CardioPulmonarybioImage Study (SCAPIS) Pilot, including static spirometry and diffusing capacity (n = 1,013; 49% women). Breathlessness was measured using the modified Medical Research Council (mMRC) scale and analyzed using ordinal logistic regression adjusting for age, pack-years of smoking, body mass index, chronic airway limitation, asthma, chronic bronchitis, depression and anxiety in all models. Results Breathlessness was twice as common in women as in men; adjusted odds ratio (OR) 2.20 (95% confidence interval, 1.32−3.66). Lower absolute lung volumes were associated with increased breathlessness prevalence in both men and women. The sex difference in breathlessness was unchanged when adjusting for lung function in %predicted, but disappeared when controlling for absolute values of total lung capacity (OR 1.12; 0.59−2.15), inspiratory capacity (OR 1.26; 0.68−2.35), forced vital capacity (OR 0.84; 0.42−1.66), forced expiratory volume in one second (OR 0.70; 0.36−1.35) or lung diffusing capacity (OR 1.07; 0.58−1.97). Conclusion In the general population, the markedly higher prevalence of breathlessness in women is related to their smaller absolute lung volumes.