Department of Radiology, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114.
Department of Radiation Oncology, University Hospital Münster, Münster, Germany.
AJR Am J Roentgenol. 2021 Jul;217(1):177-185. doi: 10.2214/AJR.20.23280. Epub 2021 Mar 17.
CT-based body composition analysis quantifies skeletal muscle and adipose tissue. However, acquisition parameters and quality can vary between CT images obtained for clinical care, which may lead to unreliable measurements and systematic error. The purpose of this study was to estimate the influence of IV contrast medium, tube current-exposure time product, tube potential, and slice thickness on cross-sectional area (CSA) and mean attenuation of subcutaneous (SAT), visceral (VAT), and inter-muscular adipose tissue (IMAT). We retrospectively analyzed 244 images from 105 patients. We applied semiautomated threshold-based segmentation to CTA, dual-energy CT, and CT images acquired as part of PET examinations. An axial image at the level of the third lumbar vertebral body was extracted from each examination to generate 139 image pairs. Images from each pair were obtained with the same scanner, from the same patient, and during the same examination. Each image pair varied in only one acquisition parameter, which allowed us to estimate the effect of the parameter using one-sample or median tests and Bland-Altman plots. IV contrast medium application reduced CSA in each adipose tissue compartment, with percentage change ranging from -0.4% ( = .03) to -9.3% ( < .001). Higher tube potential reduced SAT CSA (median percentage change, -4.2%; < .001) and VAT CSA (median percentage change, -2.8%; = .001) and increased IMAT CSA (median percentage change, -5.4%; = .001). Thinner slices increased CSA in the VAT (mean percentage change, 3.0%; = .005) and IMAT (median percentage change, 17.3%; < .001) compartments. Lower tube current-exposure time product had a variable effect on CSA (median percentage change, -3.2% for SAT [ < .001], -12.6% for VAT [ = .001], and 58.8% for IMAT [ < .001]). IV contrast medium and higher tube potential increased mean attenuation, with percentage change ranging from 0.8% to 1.7% ( < .05) and from 6.2% to 20.8% ( < .001), respectively. Conversely, thinner slice and lower tube current-exposure time product reduced mean attenuation, with percentage change ranging from -5.4% to -1.0% ( < .001) and from -8.7% to -1.8% ( < .001), respectively. Acquisition parameters significantly affect CSA and mean attenuation of adipose tissue. Details of acquisition parameters used for CT-based body composition analysis need to be scrutinized and reported to facilitate interpretation of research studies.
CT 基础的身体成分分析定量评估骨骼肌和脂肪组织。然而，临床护理中获得的 CT 图像的采集参数和质量可能存在差异，这可能导致测量结果不可靠和系统误差。本研究的目的是评估 IV 对比剂、管电流-曝光时间乘积、管电压和层厚对皮下（SAT）、内脏（VAT）和肌间脂肪组织（IMAT）的横截面积（CSA）和平均衰减的影响。
我们回顾性分析了 105 例患者的 244 幅图像。我们应用半自动基于阈值的分割对 CTA、双能 CT 和 PET 检查中获得的 CT 图像进行了分析。从每项检查中提取第三腰椎水平的轴向图像，生成 139 对图像。每对图像均来自同一台扫描仪、同一患者且在同一检查中获得。每对图像的采集参数只有一项不同，这使我们能够使用单样本或中位数检验和 Bland-Altman 图来估计参数的影响。
IV 对比剂的应用降低了每个脂肪组织隔室的 CSA，百分比变化范围为-0.4%（ =.03）至-9.3%（ <.001）。较高的管电压降低了 SAT CSA（中位数百分比变化，-4.2%； <.001）和 VAT CSA（中位数百分比变化，-2.8%； =.001），并增加了 IMAT CSA（中位数百分比变化，-5.4%； =.001）。更薄的切片增加了 VAT（平均百分比变化，3.0%； =.005）和 IMAT（中位数百分比变化，17.3%； <.001）隔室的 CSA。较低的管电流-曝光时间乘积对 CSA 有不同的影响（SAT 的中位数百分比变化，-3.2%[ <.001]，VAT 的-12.6%[ =.001]，IMAT 的 58.8%[ <.001]）。IV 对比剂和较高的管电压增加了平均衰减，百分比变化范围为 0.8%至 1.7%（ <.05）和 6.2%至 20.8%（ <.001）。相反，更薄的切片和更低的管电流-曝光时间乘积降低了平均衰减，百分比变化范围为-5.4%至-1.0%（ <.001）和-8.7%至-1.8%（ <.001）。
采集参数会显著影响脂肪组织的 CSA 和平均衰减。需要仔细检查和报告 CT 基础身体成分分析中使用的采集参数的详细信息，以促进研究结果的解释。
