OBJECTIVE The purpose of this study was to characterize human brown adipose tissue (BAT) with chemical-shift water-fat MRI and to determine whether trends and differences in fat-signal fractions and T2* relaxation times between BAT and white adipose tissue (WAT) are consistently observed postmortem and in vivo in infants, adolescents, and adults. MATERIALS AND METHODS A postmortem body and eight patients were studied. A six-echo spoiled gradient-echo chemical-shift water-fat MRI sequence was performed at 3 T to jointly quantify fat-signal fraction and T2* in interscapular-supraclavicular BAT and subcutaneous WAT. To confirm BAT identity, biopsy and histology served as the reference in the postmortem study and PET/CT was used in five of the eight patients who required examination for medical care. RESULTS Fat-signal fractions and T2* times were lower in BAT than in WAT in the postmortem example and in seven of eight patients. With the exception of one case, nominal comparisons between brown and white adipose tissues were statistically significant (p < 0.05). Between subjects, a large range of fat-signal fraction values was observed in BAT but not in WAT. CONCLUSION We have shown that fat-signal fractions and T2* values jointly derived from chemical-shift water-fat MRI are lower in BAT than in WAT likely because of differences in cellular structures, triglyceride content, and vascularization. The two metrics can serve as complementary biomarkers in the detection of BAT.

Purpose To compare fat-signal fractions (FFs) and T2* values between brown (BAT) and white (WAT) adipose tissue located within the supraclavicular fossa and subcutaneous depots, respectively. Materials and Methods Twelve infants and 39 children were studied. Children were divided into lean and overweight/obese sub-groups. Chemical-shift-encoded water-fat MRI was used to quantify FFs and T2* metrics in the supraclavicular and adjacent subcutaneous adipose tissue depots. Linear regression and t-tests were performed. Results Infants had lower supraclavicular FFs than children (p<0.01) but T2* values were similar (p=0.5). Lean children exhibited lower supraclavicular FFs and T2* values than overweight children (p<0.01). In each individual infant and child, supraclavicular FFs were consistently lower than adjacent subcutaneous FFs. Supraclavicular T2* values were consistently lower than subcutaneous T2* values in children, but not in infants. FFs in both depots were positively correlated with age and weight in infants (p<0.01). In children, they were correlated with weight and BMI (p<0.01), but not age. Correlations between T2* and anthropometric variables existed in children (p<0.01), but were absent in infants. Conclusion Cross-sectional comparisons suggest variations in FF and T2* values in the supraclavicular and subcutaneous depots of infants and children, which are potentially indicative of physiological differences in adipose tissue fat content, amount, and metabolic activity.

We hypothesized that the distinct maturational processes take place across different cortical areas from middle fetal stage to normal time of birth and these maturational processes are altered in late third trimester. Fractional anisotropies (FA) from diffusion tensor imaging (DTI) infer the microstructures of the early developing cortical plate. High-resolution DTI of 11 fetal brain specimens at postmenstrual age of 20 weeks (or simplified as 20 weeks), 19 in vivo brains at 35 weeks, and 17 in vivo brains at normal time of birth at term (40 weeks) were acquired. Population-averaged age-specific DTI templates were established with large deformation diffeomorphic metric mapping for subject groups at 20, 35, and 40 weeks. To alleviate partial volume effects, skeletonized FA values were used for mapping averaged cortical FA to the cortical surface and measuring FA at 12 functionally distinctive cortical regions. Significant and heterogeneous FA decreases take place in distinct cortical areas from 20 to 35 weeks and from 35 to 40 weeks, suggesting differentiated cortical development patterns. Temporally nonuniform FA decrease patterns during 35-40 weeks compared with those during 20-35 weeks were observed in higher-order association cortex. Measured skeletonized FA suggested dissociated changes between cerebral cortex and white matter during 35-40 weeks.

DTI measures of muscle structure strongly correlated with muscle strength and adiposity in boys with DMD in this pilot study, although these markers may be more reflective of fat replacement rather than muscle damage in later stages of the disease. Further studies in presymptomatic younger children are needed to assess the ability of DTI to detect early changes in DMD.

Purpose-To compare fat-signal fractions (FFs) and T 2 * values between brown (BAT) and white (WAT) adipose tissue located within the supraclavicular fossa and subcutaneous depots, respectively.Materials and Methods-Twelve infants and 39 children were studied. Children were divided into lean and overweight/obese sub-groups. Chemical-shift-encoded water-fat MRI was used to quantify FFs and T 2 * metrics in the supraclavicular and adjacent subcutaneous adipose tissue depots. Linear regression and t-tests were performed.Results-Infants had lower supraclavicular FFs than children (p<0.01) but T 2 * values were similar (p=0.5). Lean children exhibited lower supraclavicular FFs and T 2 * values than overweight children (p<0.01). In each individual infant and child, supraclavicular FFs were consistently lower than adjacent subcutaneous FFs. Supraclavicular T 2 * values were consistently lower than subcutaneous T 2 * values in children, but not in infants. FFs in both depots were positively correlated with age and weight in infants (p<0.01). In children, they were correlated with weight and BMI (p<0.01), but not age. Correlations between T 2 * and anthropometric variables existed in children (p<0.01), but were absent in infants.Conclusion-Cross-sectional comparisons suggest variations in FF and T 2 * values in the supraclavicular and subcutaneous depots of infants and children, which are potentially indicative of physiological differences in adipose tissue fat content, amount, and metabolic activity.