Department of Radiology, Zhongda Hospital, Jiangsu Key Laboratory of Molecular and Functional Imaging, Medical School of Southeast University, Nanjing, China.
Korean J Radiol. 2020 Feb;21(2):248-256. doi: 10.3348/kjr.2019.0111.
The purpose of the study was to non-invasively characterize and discriminate brown adipose tissue (BAT) from white adipose tissue (WAT) in rats using spectral computed tomography (CT) with histological validation.
A lipid-containing phantom (lipid fractions from 0% to 100%) was imaged with spectral CT. An , non-enhanced spectral CT scan was performed on 24 rats, and fat concentrations of BAT and WAT were measured. The rats were randomized to receive intraperitoneal treatment with norepinephrine (NE) (n = 12) or saline (n = 12). Non-enhanced and enhanced spectral CT scans were performed after treatment to measure the elevation of iodine in BAT and WAT. The BAT/aorta and WAT/aorta ratios were calculated and compared, after which isolated BAT and WAT samples were subjected to histological and uncoupling protein 1 (UCP1) analyses.
The ex-vivo phantom study showed excellent linear fit between measured fat concentration and the known gravimetric reference standard (² = 0.996). , BAT had significantly lower fat concentration than WAT ( < 0.001). Compared to the saline group, the iodine concentration of BAT increased significantly ( < 0.001) after injection of NE, while the iodine concentration of WAT only changed slightly. The BAT/aorta ratio also increased significantly after exposure to NE compared to the saline group ( < 0.001). Histological and UCP1 expression analyses supported the spectral CT imaging results.
The study consolidates spectral CT as a new approach for non-invasive imaging of BAT and WAT. Quantitative analyses of BAT and WAT by spectral CT revealed different characteristics and pharmacologic activations in the two types of adipose tissue.
本研究旨在通过具有组织学验证的光谱 CT 无创地对大鼠棕色脂肪组织（BAT）和白色脂肪组织（WAT）进行特征描述和区分。
对含有脂质的体模（脂质分数从 0%到 100%）进行光谱 CT 成像。对 24 只大鼠进行非增强光谱 CT 扫描，并测量 BAT 和 WAT 的脂肪浓度。大鼠随机分为接受去甲肾上腺素（NE）腹腔内治疗组（n = 12）或生理盐水组（n = 12）。治疗后进行非增强和增强光谱 CT 扫描，以测量 BAT 和 WAT 中碘的升高。计算并比较 BAT/主动脉和 WAT/主动脉比值，然后对分离的 BAT 和 WAT 样本进行组织学和解偶联蛋白 1（UCP1）分析。
离体体模研究表明，测量的脂肪浓度与已知重量参考标准之间具有极好的线性拟合（² = 0.996）。与 WAT 相比，BAT 的脂肪浓度明显较低（<0.001）。与生理盐水组相比，NE 注射后 BAT 中的碘浓度显著增加（<0.001），而 WAT 中的碘浓度仅略有变化。与生理盐水组相比，NE 暴露后 BAT/主动脉比值也显著增加（<0.001）。光谱 CT 成像结果得到组织学和 UCP1 表达分析的支持。
该研究将光谱 CT 作为 BAT 和 WAT 无创成像的新方法进行了整合。通过光谱 CT 对 BAT 和 WAT 进行定量分析，揭示了两种脂肪组织的不同特征和药理学激活。
