Comparison of abdominal visceral adipose tissue measurements in adolescents between magnetic resonance imaging and dual-energy X-ray absorptiometry

Adolescent Diet Quality, Cardiometabolic Risk, and Adiposity: A Prospective Cohort

OBJECTIVE

Examine the prospective association among diet with adolescent cardiometabolic risk (CMR) and anthropometrics.

METHODS

Secondary analysis of an observational study of adolescents aged 10-16 years. Twenty-four-hour food recalls were used to calculate Healthy Eating Index-2015 (HEI-2015) scores. Anthropometrics were assessed using magnetic resonance imaging, dual-energy x-ray absorptiometry, and height/weight measurements. CMR included mean arterial pressure, homeostatic model assessment for insulin resistance, high-density lipoprotein cholesterol, and triglycerides. Associations between HEI-2015 score at baseline with follow-up adiposity and CMR were examined using regression models.

RESULTS

A total of 192 adolescents were included. Baseline HEI-2015 scores were inversely associated with follow-up total CMR z-score (P = 0.01), homeostatic model assessment for insulin resistance (P < 0.01), waist circumference z-score (P = 0.02), body mass index percentile (P = 0.01), fat mass (P = 0.04), lean mass (P = 0.02), and visceral adipose tissue mass (P = 0.01).

CONCLUSIONS AND IMPLICATIONS

Adolescents with lower adherence to dietary guidelines and greater CMR and anthropometry measurements at baseline continued this trajectory across the observation.

Visceral, subcutaneous, and total fat mass accumulation in a prospective cohort of adolescents

BACKGROUND

Race and sex differences in adolescents' body fat are demonstrated in cross-sectional cohorts, yet a longitudinal design would better identify patterns of fat distribution over time.

OBJECTIVES

The aim was to examine race and sex differences in adiposity between black and white adolescents over 2 y.

METHODS

A cohort of adolescents aged 10-16 y (38% black; 52% girls; 15% overweight, 34% with obesity) underwent body composition measurements at baseline (n = 309) and 2 y later (n = 236), using DXA to quantify whole-body fat mass (FM) and MRI for abdominal subcutaneous (SAT) and visceral adipose tissue (VAT) volumes. General linear models were used to examine race and sex differences in log-transformed FM, SAT, and VAT, adjusting for age, sexual maturation, extended BMI percentile, and race-by-sex interaction. SAT and VAT models in addition controlled for baseline FM and change in FM (for change models).

RESULTS

Mean (95% CI) baseline FM (kg) was higher among white [18.5 (17.9, 19.2) than among black adolescents [17.4 (16.6, 18.2), P = 0.03] and girls [19.5 (18.8, 20.3) than boys [16.5 (15.8, 17.2), P < 0.0001]. Mean (95% CI) baseline SAT (L) was higher among girls [4.4 (4.2, 4.6)] than among boys [3.9 (3.7, 4.1), P < 0.0001]. Mean (95% CI) baseline VAT (L) was higher among white [0.5 (0.5, 0.6)] than among black [0.3 (0.3, 0.4)] adolescents (P < 0.0001) and boys [0.5 (0.4, 0.5)] than girls [0.4 (0.4, 0.4), P = 0.04]. Over 2 y mean (95% CI) FM change (kg) was higher among white [3.7 (2.9, 4.5)] than among black adolescents [2.3 (1.3, 3.3), P = 0.04] and girls [4.0 (3.0, 4.9)] than boys [2.0 (1.1, 3.0), P = 0.007], but SAT change (L) did not differ by race or sex. VAT change (L) was higher among white [0.1 (0.1, 0.1)] than among black adolescents [0.0 (0.0, 0.1), P = 0.003] and boys [0.1 (0.1, 0.1)] than girls [0.0 (0.0, 0.1), P = 0.034].

CONCLUSIONS

Sex and race differences in the deposition and accumulation of excess fat are important considerations for understanding obesity prevalence and obesity-related disease risk among adolescents.This trial was registered at clinicaltrials.gov as NCT02784509.

Validity of dual-energy x-ray absorptiometry for estimation of visceral adipose tissue and visceral adipose tissue change after surgery-induced weight loss in women with severe obesity

OBJECTIVE

Reliable and simple methods to quantify visceral adipose tissue (VAT) and VAT changes are needed. This study investigated the validity of dual-energy x-ray absorptiometry (DXA) compared with magnetic resonance imaging (MRI) for estimating VAT cross sectionally and longitudinally after surgery-induced weight loss in women with severe obesity.

METHODS

Women with obesity (n = 36; mean age 43 [SD 10] years; 89% White) with DXA and MRI before bariatric surgery (T0) at 12 (T12) and 24 months (T24) post surgery were included. CoreScan (GE Healthcare, Chicago, Illinois) estimated VAT from 20% of the distance between the top of the iliac crest and the base of the skull. MRI VAT (total VAT) was measured from the base of the heart to the sacrum/coccyx on a whole-body scan.

RESULTS

Mean DXA VAT was 45% of MRI VAT at T0, 46% at T12, and 68% at T24. DXA underestimated change in MRI VAT between T0 and T12 by 26.1% (0.81 kg, p = 0.03) and by 71.7% (0.43 kg, p < 0.001) between T12 and T24. The relationship between DXA VAT and MRI VAT differed between T12 and T24 (p value for interaction = 0.03).

CONCLUSIONS

CoreScan lacks validity for comparing VAT across individuals or for estimating the size of changes within individuals; however, within the limits of measurement error, it may provide a useful indicator of whether some VAT change has occurred within an individual.

Subcutaneous and visceral fat assessment by DXA and MRI in older adults and children

OBJECTIVE

Given the importance of body fat distribution in chronic disease development, feasible methods to assess body fat are essential. This study compared dual-energy x-ray absorptiometry (DXA) in measuring visceral and subcutaneous adipose tissue (VAT and SAT) with magnetic resonance imaging (MRI).

METHODS

VAT and SAT were assessed using similar DXA and MRI protocols among 1,795 elderly participants of the Adiposity Phenotype Study (APS) and 309 children/adolescents in Shape Up! Kids (SKids). Spearman correlations, Bland-Altman plots, and coefficients of determination (R2 ) assessed agreement between DXA and MRI measures.

RESULTS

DXA overestimated SAT values in APS (315 vs. 229 cm2 ) and SKids (212 vs. 161 cm2 ), whereas DXA underestimated VAT measures (141 vs. 167 cm2 ) in adults only. The correlations between DXA and MRI values were stronger for SAT than VAT (APS: r = 0.92 vs. 0.88; SKids: 0.90 vs. 0.74). Bland-Altman plots confirmed better agreement for SAT than VAT despite differences by sex, ethnicity, and weight status with respective R2 values for SAT and VAT of 0.88 and 0.84 (APS) and 0.81 and 0.69 (SKids).

CONCLUSION

These findings indicate that SAT by DXA reflects MRI measures in children and older adults, whereas agreement for VAT is weaker for individuals with low VAT levels.

Comparison between DXA and MRI for the Visceral Fat Assessment in Athletes

The use of dual-energy X-ray absorptiometry (DXA) may be invalid for assessing athletes with larger bodies, larger lean body mass, and thicker trunks. This study compared the athletes' visceral adipose tissue (VAT) assessed using DXA and magnetic resonance imaging (MRI). Eighty-two Japanese male collegiate athletes from 18 sports participated in this study. VAT was assessed using the dual-energy scan that coincided with the 4th lumbar vertebra. The sum of eight magnetic resonance slices corresponding to the region of the dual-energy scan was used for comparison. The VAT volume was higher with the dual-energy scan than with MRI (difference: 35 cm³, p<0.01). A significant correlation was noted between the volumes measured using both modalities (r=0.88, p<0.01). Magnetic resonance-derived volumes less than 600 cm³ showed a stronger significant correlation with dual-energy-derived volumes. However, magnetic resonance-derived VAT volumes exceeding 600 cm³ were not significantly correlated with dual-energy-derived volumes. In conclusion, VAT volumes derived from DXA were larger and significantly correlated with those derived from MRI across a wide range of values. Methods using DXA for assessing the visceral fat volume may require adjustment to estimate abdominal visceral fat volume in athletes, with care taken when using such methods for heavyweight athletes.