Cohen M D, McGuire W, Cory D A, Smith J A
AJR Am J Roentgenol. 1986 Jun;146(6):1293-7. doi: 10.2214/ajr.146.6.1293.
There are conflicting reports on the appearance of blood and blood clot as seen in the human body by MRI. This study was designed to show the in vitro MR signal intensity of human blood products in the fresh state and to evaluate the serial MRI changes that occur over time (2 weeks). T1 relaxation times were also measured. Anticoagulated whole blood, plasma, serum, white blood cell concentrates, platelet concentrates, lysed red cells, red cell concentrates, and blood clot were studied. The results show that plasma and serum have similar T1 values, as do lysed and intact erythrocytes. T1 of serum and plasma rose initially and then fell with the aging of the samples. T1 of red blood cells, clot, and packed red blood cells decreased for the first 48 hr and then remained constant for 7 days before increasing to the initial values by 2 weeks. Platelets and white blood cells had little influence on the MR image. However, temperature had a significant effect on T1 and signal intensity. In vivo clots are complex mixtures of whole clot, lysing clot, serum, and plasma influenced in various ways by the adjacent normal or diseased tissues. The chemical and physical properties of the mixture change constantly. Because of the clot's complex nature, determining the age of a hematoma from the appearance of clots on the MR image may not be possible.
关于MRI观察到的人体血液和血凝块的表现，存在相互矛盾的报道。本研究旨在展示新鲜状态下人体血液制品的体外MR信号强度，并评估随时间（2周）发生的系列MRI变化。还测量了T1弛豫时间。研究了抗凝全血、血浆、血清、白细胞浓缩物、血小板浓缩物、裂解红细胞、红细胞浓缩物和血凝块。结果表明，血浆和血清具有相似的T1值，裂解红细胞和完整红细胞也是如此。血清和血浆的T1最初升高，然后随着样本老化而下降。红细胞、血凝块和红细胞压积的T1在最初48小时下降，然后在7天内保持恒定，到2周时增加到初始值。血小板和白细胞对MR图像影响很小。然而，温度对T1和信号强度有显著影响。体内血凝块是全血凝块、溶解血凝块、血清和血浆的复杂混合物，受到相邻正常或病变组织的各种影响。混合物的化学和物理性质不断变化。由于血凝块的复杂性质，从MR图像上血凝块的外观确定血肿的年龄可能是不可能的。
