School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, 85295, USA.
Department of Radiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, 75390, USA.
Sci Rep. 2020 Jan 29;10(1):1399. doi: 10.1038/s41598-020-57889-9.
Tissue oximetry can assist in diagnosis and prognosis of many diseases and enable personalized therapy. Previously, we reported the ability of hexamethyldisiloxane (HMDSO) for accurate measurements of tissue oxygen tension (pO) using Proton Imaging of Siloxanes to map Tissue Oxygenation Levels (PISTOL) magnetic resonance imaging. Here we report the feasibility of several commercially available linear and cyclic siloxanes (molecular weight 162-410 g/mol) as PISTOL-based oxygen reporters by characterizing their calibration constants. Further, field and temperature dependence of pO calibration curves of HMDSO, octamethyltrisiloxane (OMTSO) and polydimethylsiloxane (PDMSO) were also studied. The spin-lattice relaxation rate R of all siloxanes studied here exhibited a linear relationship with oxygenation (R = A' + B'*pO) at all temperatures and field strengths evaluated here. The sensitivity index η( = B'/A') decreased with increasing molecular weight with values ranged from 4.7 × 10-11.6 × 10 torr at 4.7 T. No substantial change in the anoxic relaxation rate and a slight decrease in pO sensitivity was observed at higher magnetic fields of 7 T and 9.4 T for HMDSO and OMTSO. Temperature dependence of calibration curves for HMDSO, OMTSO and PDMSO was small and simulated errors in pO measurement were 1-2 torr/°C. In summary, we have demonstrated the feasibility of various linear and cyclic siloxanes as pO-reporters for PISTOL-based oximetry.
组织氧饱和度测定法可以协助诊断和预测多种疾病，并实现个体化治疗。此前，我们曾报道过使用硅氧烷质子成像来测定组织氧合水平（PISTOL）磁共振成像中的六甲基二硅氧烷（HMDSO），以实现组织氧分压（pO2）的准确测量。在此，我们报告了几种市售的线性和环状硅氧烷（分子量 162-410g/mol）作为基于 PISTOL 的氧报告分子的可行性，方法是对它们的校准常数进行了表征。此外，我们还研究了 HMDSO、八甲基三硅氧烷（OMTSO）和聚二甲基硅氧烷（PDMSO）的 pO2 校准曲线的场强和温度依赖性。在此评估的所有温度和场强下，所有研究的硅氧烷的自旋晶格弛豫率 R 都与氧合作用呈线性关系（R=A'+B'*pO）。灵敏度指数 η（=B'/A'）随分子量的增加而降低，在 4.7T 时，其值范围为 4.7×10-11.6×10 torr。在更高的磁场 7T 和 9.4T 下，HMDSO 和 OMTSO 的缺氧弛豫率没有明显变化，pO2 灵敏度略有降低。HMDSO、OMTSO 和 PDMSO 的校准曲线的温度依赖性较小，pO2 测量的模拟误差为 1-2torr/℃。总之，我们已经证明了各种线性和环状硅氧烷作为 PISTOL 氧饱和度测定法的 pO2 报告分子的可行性。
