Comparison of dual-energy X-ray absorptiometry and magnetic resonance imaging-measured adipose tissue depots in HIV-infected and control subjects

University of California, San Francisco, CA 94121, USA.
American Journal of Clinical Nutrition (Impact Factor: 6.77). 10/2008; 88(4):1088-96.
Source: PubMed


Studies in persons without HIV infection have compared adipose tissue measured by dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI), but no such study has been conducted in HIV-infected (HIV+) subjects, who have a high prevalence of regional fat loss.
We compared DXA- with MRI-measured trunk, leg, arm, and total fat in HIV+ and control subjects.
A cross-sectional analysis was conducted in 877 HIV+ subjects and 260 control subjects in FRAM (Study of Fat Redistribution and Metabolic Change in HIV Infection), stratified by sex and HIV status.
Univariate associations of DXA with MRI were strongest for total and trunk fat (r > or = 0.92) and slightly weaker for leg (r > or = 0.87) and arm (r > or = 0.71) fat. The average estimated limb fat was substantially greater for DXA than for MRI for HIV+ and control men and women (all P < 0.0001). Less of a difference was observed in trunk fat measured by DXA and MRI, but the difference was still statistically significant (P < 0.0001). Bland-Altman plots showed increasing differences and variability. Greater average limb fat in control and HIV+ subjects (both P < 0.0001) was associated with greater differences between DXA and MRI measurements. Because the control subjects had more limb fat than did the HIV+ subjects, greater amounts of fat were measured by DXA than by MRI when control subjects were compared with HIV+ subjects. More HIV+ subjects had leg fat in the bottom decile of the control subjects by DXA than by MRI (P < 0.0001).
Although DXA- and MRI-measured adipose tissue depots correlate strongly in HIV+ and control subjects, differences increase as average fat increases, particularly for limb fat. DXA may estimate a higher prevalence of peripheral lipoatrophy than does MRI in HIV+ subjects.

7 Reads
  • Source
    • "Dual energy X-ray absorptiometry significantly underestimated total leg AT and bone tissue, while it overestimated leg soft tissue mass. This finding is supported by previous validation work in elderly persons (Chen et al., 2007; Levine et al., 2000), but in contrast with recent findings of Scherzer et al. (2008) who found that fat DXA overestimated MRI-derived leg AT in middle-aged HIV positive adults and normal controls . Although it can be pointed out that these groups present significantly smaller amounts of intermuscular AT compared to elderly subjects, the reasons for these contradictory findings remain unclear. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Since dual energy X-ray absorptiometry (DXA) cannot distinguish between different adipose tissue (AT) deposits, it remains unclear how DXA-derived body composition variables relate to anatomical tissue (sub)compartments. The aim of the present study was to compare and relate regional DXA variables with absolute tissue masses obtained by computer tomography (CT) scanning of the lower limbs in elderly persons. Eleven well-preserved white Caucasian adults (seven male and four female cadavers) with a median age of 79.0 years (ranging from 68 to 96 years) were fully scanned with DXA and CT. Separate densities of skin tissue, AT, muscle tissue and bone were obtained by hydrostatic weighing. The leg DXA-variables were significantly related (rho-values between 0.60 and 0.98, P<0.01) to CT-derived tissue counterparts, but showed significant systematic differences except for subcutaneous AT mass (P=0.773). After controlling for other AT depots, fat as measured by DXA (fatDXA) related only to intermuscular AT (rho=0.82, P<0.01) in males and to subcutaneous AT (rho=0.84, P<0.05) in females. Although significantly interrelated, DXA and CT variables should not be used interchangeably since they have different quantitative and physiological significance. Our results suggest that fatDXA represents different parts of AT depots in elderly men and women. Since DXA is not appropriate for assessing tissue variability cautious clinical interpretation is warranted.
    Experimental gerontology 07/2013; 48(9). DOI:10.1016/j.exger.2013.07.005 · 3.49 Impact Factor
  • Source
    • "However, weaker correlations have been observed, supporting our hypothesis that while a number of techniques perform well across larger populations, there remains significant intraindividual variability. In another study, DEXA-estimated fat was correlated with MRI quantification of adipose tissue, but in 877 HIV+ and 260 healthy adults, DEXA significantly overestimated total and regional fat mass (P < 0.0001).73 Importantly, as the amount of body fat mass increased (ie, greater adiposity), the DEXA overestimates were proportionally larger, which would confound assessment of metabolic risk. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Obesity is a threat to public health worldwide primarily due to the comorbidities related to visceral adiposity, inflammation, and insulin resistance that increase risk for type 2 diabetes and cardiovascular disease. The translational research portfolio that originally described these risk factors was significantly enhanced by imaging techniques, such as dual-energy X-ray absorptiometry (DEXA), computed tomography (CT), and magnetic resonance imaging (MRI). In this article, we briefly review the important contributions of these techniques to understand the role of body composition in the pathogenesis of obesity-related complications. Notably, these imaging techniques have contributed greatly to recent findings identifying gender and racial differences in body composition and patterns of body composition change during weight loss. Although these techniques have the ability to generate good-quality body composition data, each possesses limitations. For example, DEXA is unable to differentiate type of fat, CT has better resolution but provides greater ionizing radiation exposure, and MRI tends to require longer imaging times and specialized equipment for acquisition and analysis. With the serious need for efficacious and cost-effective therapies to appropriately identify and treat at-risk obese individuals, there is greater need for translational tools that can further elucidate the interplay between body composition and the metabolic aberrations associated with obesity. In conclusion, we will offer our perspective on the evolution toward an ideal imaging method for body composition assessment in obesity and weight loss, and the challenges remaining to achieve this goal.
    Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy 09/2010; 3:337-47. DOI:10.2147/DMSOTT.S9454
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper discusses the technique for asynchronous circuit design using a novel asynchronous control unit. We employ the very commonly used device, pass-transistor multiplexer, to design and implement the asynchronous control unit. Even though the architecture of the control unit is simple, the efficiency is good. A multiplier with pipelined structure has been designed to verify the usefulness of this technique. We use TSMC's 0.6 μm SPDM process to design and implement an 8-b×8-b pipelined multiplier. The HSPICE simulation shows that the feedthrough rate of the inputs can be as high as 250 MHz
    Circuits and Systems, 1998. ISCAS '98. Proceedings of the 1998 IEEE International Symposium on; 01/1998
Show more


7 Reads
Available from