Objective

To determine the variability, and preferred values, for normal liver longitudinal water proton relaxation rate R₁ in the published literature.

Methods

Values of mean R₁ and between-subject variance were obtained from literature searching. Weighted means were fitted to a heuristic and to a model.

Results

After exclusions, 116 publications (143 studies) remained, representing apparently normal liver in 3392 humans, 99 mice and 249 rats. Seventeen field strengths were included between 0.04 T and 9.4 T. Older studies tended to report higher between-subject coefficients of variation (CoV), but for studies published since 1992, the median between-subject CoV was 7.4%, and in half of those studies, measured R₁ deviated from model by 8.0% or less.

Discussion

The within-study between-subject CoV incorporates repeatability error and true between-subject variation. Between-study variation also incorporates between-population variation, together with bias from interactions between methodology and physiology. While quantitative relaxometry ultimately requires validation with phantoms and analysis of propagation of errors, this survey allows investigators to compare their own R₁ and variability values with the range of existing literature.

中文翻译：

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体内肝脏水质子纵向弛豫研究

客观的

确定已发表文献中正常肝脏纵向水质子弛豫率R ₁的变异性和优选值。

方法

均值R ₁和受试者间方差的值是从文献检索中获得的。加权平均值适合启发式和模型。

结果

排除后，剩下 116 篇出版物（143 项研究），代表 3392 人、99 只小鼠和 249 只大鼠的明显正常肝脏。17 个场强介于 0.04 T 和 9.4 T 之间。较早的研究倾向于报告更高的受试者间变异系数 (CoV)，但对于自 1992 年以来发表的研究，受试者间 CoV 的中位数为 7.4%，其中一半研究，测得的R ₁偏离模型 8.0% 或更少。

讨论

研究内受试者之间的 CoV 包含可重复性误差和真实的受试者间变异。研究间变异还包括人群间变异，以及方法学和生理学之间相互作用的偏差。虽然定量弛豫测量最终需要使用模型验证和分析误差传播，但这项调查允许调查人员将他们自己的R ₁和可变性值与现有文献的范围进行比较。