Ma Yuhan, Berman Avery J L, Pike G Bruce
McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
Department of Radiology and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
Magn Reson Med. 2016 Dec;76(6):1905-1911. doi: 10.1002/mrm.26069. Epub 2015 Dec 2.
To determine the contribution of paramagnetic dissolved oxygen in blood plasma to blood-oxygenation-level-dependent (BOLD) signal changes in hyperoxic calibrated BOLD studies.
Bovine blood plasma samples were prepared with partial pressures of oxygen (pO ) ranging from 110 to 600 mmHg. R , R , and R of the plasma with dissolved oxygen were measured using quantitative MRI sequences at 3 Tesla. Simulations were performed to predict the relative effects of dissolved oxygen and deoxyhemoglobin changes in hyperoxia calibrated BOLD.
The relaxivities of dissolved oxygen in plasma were found to be r =1.97 ± 0.09 ×10 s mmHg , r =2.3 ± 0.7 ×10 s mmHg , and r = 2.3 ± 0.7 ×10 s mmHg . Simulations predict that neither the transverse nor longitudinal relaxation rates of dissolved oxygen contribute significantly to the BOLD signal during hyperoxia.
During hyperoxia, the increases in R and R of blood from dissolved oxygen in plasma are considerably less than the decreases in R and R from venous deoxyhemoglobin. R effects due to dissolved oxygen are also predicted to be negligible. As a result, dissolved oxygen in arteries should not contribute significantly to the hyperoxic calibrated BOLD signal. Magn Reson Med 76:1905-1911, 2016. © 2015 International Society for Magnetic Resonance in Medicine.
在高氧校准的血氧水平依赖（BOLD）研究中，确定血浆中顺磁性溶解氧对BOLD信号变化的贡献。
制备氧分压（pO）范围为110至600 mmHg的牛血浆样本。使用3特斯拉的定量MRI序列测量含有溶解氧的血浆的R1、R2和R2*。进行模拟以预测高氧校准BOLD中溶解氧和脱氧血红蛋白变化的相对影响。
发现血浆中溶解氧的弛豫率为r1 = 1.97±0.09×10−3 s−1 mmHg−1，r2 = 2.3±0.7×10−3 s−1 mmHg−1，r2* = 2.3±0.7×10−3 s−1 mmHg−1。模拟预测，在高氧期间，溶解氧的横向和纵向弛豫率对BOLD信号均无显著贡献。
在高氧期间，血浆中溶解氧导致的血液R1和R2增加远小于静脉脱氧血红蛋白导致的R1和R2降低。预计溶解氧引起的R2*效应也可忽略不计。因此，动脉中的溶解氧对高氧校准的BOLD信号不应有显著贡献。《磁共振医学》76:1905 - 1911, 2016。© 2015国际磁共振医学学会。
