Neeland I J, Grundy S M, Li X, Adams-Huet B, Vega G L
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
Dallas VA North Texas Health Care System, Dallas, TX, USA.
Nutr Diabetes. 2016 Jul 18;6(7):e221. doi: 10.1038/nutd.2016.28.
BACKGROUND/OBJECTIVES: Visceral adipose tissue (VAT) mass, a risk factor for cardiometabolic complications of obesity, is usually measured by magnetic resonance imaging (MRI) but this method is not practical in a clinical setting. In contrast, measurement of VAT by dual-x-ray absorptiometry (DXA) appears to circumvent the limitations of MRI. In this study, we compared measurements of VAT mass by MRI and DXA in the large, multiethnic cohort of the Dallas Heart Study (DHS).
SUBJECTS/METHODS: About 2689 DHS participants underwent paired measurement of VAT by MRI and DXA. Sex-stratified analyses were performed to evaluate the correlation and agreement between DXA and MRI. Model validation was performed using bootstrapping and inter-reader variability was assessed.
Mean age of the cohort was 44 years, with 55% female, 48% Black and 75% overweight/obese participants. Regression analysis showed a linear relationship between DXA and MRI with R(2)=0.82 (95% confidence interval (CI) 0.81-0.84) for females and R(2)=0.86 (95% CI 0.85-0.88) for males. Mean difference between methods was 0.01 kg for females and 0.09 kg for males. Bland-Altman analysis showed that DXA tended to modestly underestimate VAT compared with MRI at lower VAT levels and overestimate it compared with MRI at higher VAT levels. Results were consistent in analyses stratified by race, body mass index status, waist girth and body fat. Inter-individual reader correlation among 50 randomly selected scans was excellent (inter-class correlation coefficient=0.997).
VAT mass quantification by DXA was both accurate and valid among a large, multiethnic cohort within a wide range of body fatness. Further studies including repeat assessments over time will help determine its long-term applicability.
背景/目的：内脏脂肪组织（VAT）量是肥胖相关心脏代谢并发症的一个危险因素，通常通过磁共振成像（MRI）进行测量，但该方法在临床环境中并不实用。相比之下，采用双能X线吸收法（DXA）测量VAT似乎可以规避MRI的局限性。在本研究中，我们在达拉斯心脏研究（DHS）这个大型多民族队列中比较了MRI和DXA对VAT量的测量结果。
受试者/方法：约2689名DHS参与者接受了MRI和DXA对VAT的配对测量。进行了性别分层分析，以评估DXA和MRI之间的相关性及一致性。使用自抽样法进行模型验证，并评估阅片者间的变异性。
该队列的平均年龄为44岁，女性占55%，黑人占48%，超重/肥胖参与者占75%。回归分析显示，DXA与MRI之间呈线性关系，女性的R² = 0.82（95%置信区间[CI] 0.81 - 0.84），男性的R² = 0.86（95% CI 0.85 - 0.88）。两种方法之间的平均差异，女性为0.01千克，男性为0.09千克。Bland - Altman分析表明，与MRI相比，在较低VAT水平时DXA往往会适度低估VAT，而在较高VAT水平时则会高估VAT。按种族、体重指数状况、腰围和体脂分层的分析结果一致。在随机选择的50次扫描中，阅片者之间的个体相关性极佳（组内相关系数 = 0.997）。
在一个大型多民族队列中，在广泛的体脂范围内，通过DXA进行VAT量的量化既准确又有效。包括长期重复评估在内的进一步研究将有助于确定其长期适用性。
