Brooks R A, Vymazal J, Bulte J W, Baumgarner C D, Tran V
Neuroimaging Branch, National Institute of Neurological and Communicative Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
J Magn Reson Imaging. 1995 Jul-Aug;5(4):446-50. doi: 10.1002/jmri.1880050414.
T2 was measured in samples of human blood and monkey brain over a field range of 0.02-1.5 Tesla, with variable interecho times, and was compared with previous data on ferritin solutions (taken with the same apparatus). 1/T2 in deoxygenated blood increased quadratically with field strength, as noted previously, but in brain gray matter the increase was linear, as also was the case in ferritin solution. In both deoxygenated blood and gray matter, 1/T2 increased with interecho time, but appeared to level off at times around 50 msec, as expected from the theory of diffusion through magnetic gradients. Diffusion times estimated by using the chemical exchange approximation were 3.4 msec for deoxygenated blood and 5.7 msec for the globus pallidus. The quadratic field dependence in blood is consistent with this same theory, but the linear dependence in brain tissue and in ferritin solutions remains unexplained.
在0.02 - 1.5特斯拉的磁场范围内，对人体血液和猴脑样本进行了T2测量，回波间隔时间可变，并与先前铁蛋白溶液的数据（使用相同仪器获取）进行了比较。如先前所述，脱氧血液中的1/T2随磁场强度呈二次方增加，但在脑灰质中增加是线性的，铁蛋白溶液中也是如此。在脱氧血液和灰质中，1/T2均随回波间隔时间增加，但在约50毫秒时似乎趋于平稳，这与通过磁梯度扩散的理论预期一致。使用化学交换近似法估计的脱氧血液扩散时间为3.4毫秒，苍白球为5.7毫秒。血液中二次方磁场依赖性与该理论一致，但脑组织和铁蛋白溶液中的线性依赖性仍无法解释。
