Taylor Jenna L, Holland David J, Coombes Jeff S, Keating Shelley E
School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD, Australia.
Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.
Int J Obes (Lond). 2021 Aug;45(8):1740-1750. doi: 10.1038/s41366-021-00840-3. Epub 2021 May 13.
BACKGROUND/OBJECTIVE: Visceral adipose tissue (VAT) is a key target of interventions for obesity-related diseases. Dual-energy x-ray absorptiometry (DXA) can estimate VAT, however its accuracy to measure longitudinal change in VAT compared to gold-standard techniques such as magnetic resonance imaging (MRI), has not been studied in adults. This study aimed to determine the accuracy of DXA compared with gold-standard MRI for cross-sectional VAT assessment, and for detecting longitudinal change in VAT.
Adults with coronary artery disease (64 ± 8 years; BMI 27.8 ± 3.5 kg/m; 88% male) were assessed for VAT by DXA and MRI at baseline (n = 34) and during implementation of an exercise intervention study at 3- and 12-months (n = 29). To match the 5.2 cm DXA measurement site for Hologic software (InnerCore), VAT cross-sectional area (CSA) was measured by MRI using a single slice at L4/L5 junction, and VAT volume measured by 10 × 5 mm slices over the L4/L5 junction. MRI slices were quantified for VAT using semi-automated specialised software. Relationships between DXA and MRI for cross-sectional VAT and longitudinal change in VAT were determined by linear regression. Accuracy between the methods was assessed by Bland-Altman analysis, with data presented as mean difference (95% confidence interval), lower and upper limits of agreement (LoA).
Strong correlations were found between DXA-VAT and MRI-VAT at baseline (r = 0.90; p < 0.001), and longitudinal change in DXA-VAT and MRI-VAT over 3- and 12-months (r = 0.67; p < 0.001). In contrast, Bland-Altman analysis revealed significant overestimation by DXA-VAT volume at baseline by 13% [-104 cm (-157, -52 cm), p < 0.001; LoA (-398, 189 cm)], and underestimation of change in DXA-VAT volume over 3-months by 33% [-41 cm (-77, -4 cm), p = 0.030; LoA (-228, 147 cm)] and 12-months by 47% [-65 cm (-114, -17 cm), p = 0.010; LoA (-316, 185 cm)]. Results were similar for VAT CSA.
Compared with MRI, DXA substantially underestimated longitudinal changes in VAT. Therefore, DXA is not currently a valid alternative to MRI for quantifying VAT changes and may under-represent the effectiveness of interventions for obesity management.
背景/目的：内脏脂肪组织（VAT）是肥胖相关疾病干预的关键靶点。双能X线吸收法（DXA）可用于估算内脏脂肪组织，但与磁共振成像（MRI）等金标准技术相比，其测量内脏脂肪组织纵向变化的准确性在成年人中尚未得到研究。本研究旨在确定DXA与金标准MRI相比，在横断面评估内脏脂肪组织以及检测内脏脂肪组织纵向变化方面的准确性。
对患有冠状动脉疾病的成年人（64±8岁；体重指数27.8±3.5kg/m²；88%为男性）在基线时（n=34）以及在一项运动干预研究实施3个月和12个月时（n=29）通过DXA和MRI评估内脏脂肪组织。为匹配Hologic软件（InnerCore）5.2厘米的DXA测量部位，通过MRI在L4/L5椎间盘连接处使用单一层面测量内脏脂肪组织横截面积（CSA），并通过L4/L5椎间盘连接处上方10×5毫米的层面测量内脏脂肪组织体积。使用半自动专业软件对MRI层面的内脏脂肪组织进行定量分析。通过线性回归确定DXA与MRI在横断面内脏脂肪组织以及内脏脂肪组织纵向变化方面的关系。通过Bland-Altman分析评估两种方法之间的准确性，数据以平均差异（95%置信区间）、一致性下限和上限（LoA）表示。
在基线时，DXA测量的内脏脂肪组织与MRI测量的内脏脂肪组织之间存在强相关性（r=0.90；p<0.001），在3个月和12个月时，DXA测量的内脏脂肪组织与MRI测量的内脏脂肪组织的纵向变化之间也存在强相关性（r=0.67；p<0.001）。相比之下，Bland-Altman分析显示，DXA测量的内脏脂肪组织体积在基线时高估了13%[-104立方厘米（-157，-52立方厘米），p<0.001；LoA（-398，189立方厘米）]，在3个月时低估了DXA测量的内脏脂肪组织体积变化的33%[-41立方厘米（-77，-4立方厘米），p=0.030；LoA（-228，147立方厘米）]，在12个月时低估了47%[-65立方厘米（-114，-17立方厘米），p=0.010；LoA（-316，185立方厘米）]。内脏脂肪组织CSA的结果相似。
与MRI相比，DXA大大低估了内脏脂肪组织的纵向变化。因此，目前DXA不是用于量化内脏脂肪组织变化的MRI的有效替代方法，可能无法充分体现肥胖管理干预措施的效果。
