Institute of Biomedical Engineering, Department of Engineering Sciences, University of Oxford, UK.
NMR Biomed. 2022 Feb;35(2):e4625. doi: 10.1002/nbm.4625. Epub 2021 Oct 2.
The change in longitudinal relaxation rate (R ) produced by oxygen has been used as a means of inferring oxygenation levels in magnetic resonance imaging in numerous applications. The relationship between oxygen partial pressure (pO ) and R is linear and reproducible, and the slope represents the relaxivity of oxygen (r ) in that material. However, there is considerable variability in the values of r reported, and they have been shown to vary by field strength and temperature. Therefore, we have compiled 28 reported empirical values of the relaxivity of oxygen as a resource for researchers. Furthermore, we provide an empirical model for estimating the relaxivity of oxygen in water, saline, plasma, and vitreous fluids, accounting for magnetic field strength and temperature. The model agrees well (R = 0.93) with the data gathered from the literature for fields ranging from 0.011 to 8.45 T and temperatures of 21-40 °C. This provides a useful resource for researchers seeking to quantify pO in simple fluids in their studies, such as water and saline phantoms, or bodily fluids such as vitreous fluids, cerebrospinal fluids, and amniotic fluids.
氧合纵向弛豫率（R ）的变化已被用作磁共振成像中推断氧合水平的一种手段，在许多应用中都有应用。氧分压（pO ）与 R 之间的关系是线性且可重现的，斜率代表该材料中氧的弛豫率（r ）。然而，报道的 r 值存在相当大的可变性，并且已经表明它们会随场强和温度而变化。因此，我们编译了 28 个已报道的氧弛豫率的经验值，作为研究人员的资源。此外，我们还提供了一个用于估计水、生理盐水、血浆和玻璃体液中氧弛豫率的经验模型，考虑了磁场强度和温度。该模型与文献中从 0.011 到 8.45 T 的磁场强度和 21-40°C 的温度范围内收集的数据吻合良好（R = 0.93）。这为研究人员在研究中定量简单流体（如水和生理盐水模拟物）或体液（如玻璃体液、脑脊液和羊水）中的 pO 提供了有用的资源。
