Bile exerts multiple functions in the liver and gut and is involved in multiple disease processes. It is secreted continuously from the liver and stored in the gallbladder until needed, and closely reflects the available bile acid pool. The study objective was therefore to develop a reliable MRS protocol and to assess variability of bile acid determination in human gallbladder. MRS measurements were performed on a 3 T MR scanner with 20 subjects to optimize protocols (26 measurements) and conduct a prospective reproducibility study (18 measurements). Measurements were carried out with subjects lying in either supine (23 scans) or prone positions (21 scans) to compare results from the two positions. For reproducibility determination, six of the 20 volunteers (three males, three females, age = 34.9 ± 10.9 years, BMI = 23.4 ± 2.1 kg/m²) were measured three times: back to back to assess technical variability and once again after three weeks to assess total variability, including additional physiological variability. A single voxel was measured in the gallbladder with respiratory triggering. For quantification, apparent T₂ times were determined and a non‐water‐suppressed spectrum was acquired. Total bile acids, glycine and taurine conjugated bile acids, and lipids including choline‐containing phospholipids were determined. Higher quality and reliability of gallbladder spectra were obtained with subjects measured in prone compared with supine position. All measurements of the reproducibility sub‐study were of sufficient quality to be included in the analysis. Average coefficients of variation within subjects for the main compounds were 37% for total variation (including physiological and technical variation) and 24% for technical variation alone. These values were much smaller than those between subjects, which were >54% for both back‐to‐back and three weeks separated measurements. These results suggest diagnostic applicability of the method, especially for longitudinal studies aiming at non‐invasive characterization of bile composition in humans with various diseases and/or interventional maneuvers.

中文翻译：

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1H-MRS 测定人胆囊中的胆汁酸——方案优化和重现性评估

胆汁在肝脏和肠道中发挥多种功能，并参与多种疾病过程。它从肝脏不断分泌并储存在胆囊中直到需要时，并密切反映可用的胆汁酸库。因此，研究目标是开发可靠的 MRS 方案并评估人胆囊中胆汁酸测定的可变性。MRS 测量是在 20 名受试者的 3 T MR 扫描仪上进行的，以优化协议（26 次测量）并进行前瞻性可重复性研究（18 次测量）。对仰卧（23 次扫描）或俯卧位（21 次扫描）的受试者进行测量，以比较两种姿势的结果。对于再现性测定，20 名志愿者中的 6 名（三名男性，三名女性，年龄 = 34.9 ± 10.9 岁，BMI = 23.4 ± 2.1 kg/m² ) 测量三次：背靠背评估技术变异性，三周后再次评估总变异性，包括额外的生理变异性。通过呼吸触发在胆囊中测量单个体素。为了量化，确定了表观T ₂倍，并获得了非水抑制光谱。测定了总胆汁酸、甘氨酸和牛磺酸结合胆汁酸以及脂质，包括含胆碱的磷脂。与仰卧位相比，俯卧位测量的受试者获得了更高质量和可靠性的胆囊光谱。重现性子研究的所有测量都具有足够的质量，可以纳入分析。变异系数平均值内主要化合物的受试者为总变异（包括生理和技术变异）的 37% 和仅技术变异的 24%。这些值远小于受试者之间的值，背对背测量和三周间隔测量均大于 54%。这些结果表明该方法的诊断适用性，特别是对于旨在对患有各种疾病和/或介入操作的人类胆汁成分进行非侵入性表征的纵向研究。