Gomori J M, Grossman R I, Asakura T, Schnall M D, Atlas S, Holland G, Mittl R L
Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia 19104.
AJNR Am J Neuroradiol. 1993 Jul-Aug;14(4):871-80.
To assess, in an in vitro model of acute hematoma, whether hemoglobin immobilization by clot and red cell membrane aging can account for the T2 shortening usually attributed to deoxyhemoglobin.
Clotted and heparinized blood samples were packed (100% hematocrit). The apparent magnetization transfer rate (AMTR), T1 and T2 relaxation rates of the samples, and images with a volunteer's head were obtained at 1.5 T.
The AMTR and T1 and T2 relaxation rates were unaffected by the presence of clot. The AMTR was unaffected by red cell aging. The diamagnetic packed blood samples, which are much denser than brain, were isointense to gray matter on T2-weighted images and had about one-fifth the AMTR of white matter.
Hemoglobin immobilization by clot structure or red cell contraction with aging is insignificant and does not contribute to the T2 shortening of acute hematoma. The low AMTR and T2 relaxation rates of diamagnetic blood appear to be caused by the mobility of hemoglobin and by the red cell's lack of immobile macromolecular structures such as those associated with nucleated brain cells.
在急性血肿的体外模型中，评估血凝块对血红蛋白的固定作用以及红细胞膜老化是否能够解释通常归因于脱氧血红蛋白的T2缩短现象。
将凝血和肝素化的血液样本进行浓缩（血细胞比容为100%）。在1.5T条件下，获取样本的表观磁化传递率（AMTR）、T1和T2弛豫率，以及志愿者头部的图像。
血凝块的存在不影响AMTR、T1和T2弛豫率。红细胞老化不影响AMTR。比脑实质密度大得多的抗磁性浓缩血液样本在T2加权图像上与灰质等信号，其AMTR约为白质的五分之一。
血凝块结构对血红蛋白的固定作用或红细胞随老化发生的收缩作用不显著，且不会导致急性血肿的T2缩短。抗磁性血液的低AMTR和T2弛豫率似乎是由血红蛋白的流动性以及红细胞缺乏与有核脑细胞相关的固定大分子结构所致。
