Cai Zimeng, Zhong Qiaoling, Zhang Daming, Feng Yanqiu, Wang Qian, Yang Yuanbo, Xu Yongzhou, Liang Changhong, Liu Zaiyi, Cai Kejia
School of Medicine, South China University of Technology, Guangzhou, China.
Department of Radiology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Southern Medical University, Guangzhou, China.
J Magn Reson Imaging. 2025 Apr;61(4):1905-1913. doi: 10.1002/jmri.29598. Epub 2024 Aug 30.
Brown adipose tissue (BAT) is metabolically activatable and plays an important role in obesity and metabolic diseases. With reduced fat-water-fraction (FWF) compared with white adipose tissue (WAT), BAT mass and its functional activation may be quantified with Z-spectra MRI, with built-in FWF and the metabolic amide proton transfer (APT) contrasts.
To investigate if Z-spectral MRI can quantify the mass and metabolic activity of adipose tissues.
Prospective.
Seven groups of 8-week-old male rats, including two groups (n = 7 per group) for in vivo MRI study and five groups (n = 5 per group) for ex vivo validation; 12 young and healthy volunteers with 6 male and 6 female.
FIELD STRENGTH/SEQUENCE: The 7 T small animal and 3 T clinical systems, T-weighted imaging, Rapid Acquisition with Relaxation Enhancement (RARE) readout based chemical exchange saturation transfer (CEST) Z-spectral MRI sequence.
Quantified FWF and APT from Z-spectra in rats before and after norepinephrine (NE) stimulation and in healthy human subjects; ex vivo measurements of total proteins in BAT from rats.
Two-tailed unpaired Student's t-tests and repeated measures ANOVA. P-value <0.05 was considered significant.
Decreased FWF (from 39.6% ± 7.2% before NE injection to 16.4% ± 7.2% 120 minutes after NE injection, P < 0.0001) and elevated APT (from 1.1% ± 0.5% before NE injection to 2.9% ± 0.5% 120 minutes after NE injection, P < 0.0001) signals in BAT were observed with in vivo Z-spectral MRI in rats injected with NE at 7 T MRI. At clinical 3 T, Z-spectral MRI was used to quantify the FWF (58.5% ± 7.2% in BAT and 73.7% ± 6.5% in WAT with P < 0.0001) and APT (2.6% ± 0.8% in BAT and 0.9% ± 0.3% in WAT with P < 0.0001) signals in healthy volunteers. APT signals of BAT were negatively correlated with the BMI in humans (r = 0.71).
Endogenous Z-spectral MRI was demonstrated to simultaneously quantify BAT mass and function based on its FWF and APT contrasts.
棕色脂肪组织（BAT）具有代谢活性，在肥胖和代谢性疾病中起重要作用。与白色脂肪组织（WAT）相比，棕色脂肪组织的脂肪-水分数（FWF）降低，利用具有内置FWF和代谢酰胺质子转移（APT）对比的Z谱MRI可以对棕色脂肪组织的质量及其功能激活进行量化。
研究Z谱MRI是否能够量化脂肪组织的质量和代谢活性。
前瞻性研究。
7组8周龄雄性大鼠，其中2组（每组n = 7）用于体内MRI研究，5组（每组n = 5）用于体外验证；12名年轻健康志愿者，其中男性6名，女性6名。
场强/序列：7T小动物和3T临床系统，T加权成像，基于快速采集弛豫增强（RARE）读出的化学交换饱和转移（CEST）Z谱MRI序列。
在去甲肾上腺素（NE）刺激前后对大鼠以及健康受试者进行Z谱量化FWF和APT；对大鼠棕色脂肪组织中的总蛋白进行体外测量。
双尾非配对学生t检验和重复测量方差分析。P值<0.05被认为具有统计学意义。
在7T MRI下，对注射NE的大鼠进行体内Z谱MRI观察到，棕色脂肪组织中FWF降低（从注射NE前的39.6%±7.2%降至注射NE后120分钟的16.4%±7.2%，P<0.0001），APT升高（从注射NE前的1.1%±0.5%升至注射NE后120分钟的2.9%±0.5%，P<0.0001）。在临床3T条件下，Z谱MRI用于量化健康志愿者棕色脂肪组织中的FWF（58.5%±7.2%）和WAT中的FWF（73.7%±6.5%）（P<0.0001）以及棕色脂肪组织中的APT（2.6%±0.8%）和WAT中的APT（0.9%±0.3%）（P<0.0001）信号。人类棕色脂肪组织的APT信号与BMI呈负相关（r = 0.71）。
内源性Z谱MRI被证明可基于其FWF和APT对比同时量化棕色脂肪组织的质量和功能。
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