Hayman L A, Ford J J, Taber K H, Saleem A, Round M E, Bryan R N
Department of Radiology, Baylor College of Medicine, Houston, TX 77030.
Radiology. 1988 Aug;168(2):489-91. doi: 10.1148/radiology.168.2.3393669.
T2 values were measured at 0.23 and 4.7 T for deoxygenated blood samples (43%-73% O2 saturation) with hematocrits of 18%-100%. An increase in the hematocrit produced a marked reduction in T2 at both field strengths. Cell lysis did not abolish the T2 effect at either field strength. The authors conclude that the increase in hemoglobin concentration caused by formation of a retracted clot is a cause of the hypointense appearance of acute hemorrhage compared with brain on T2-weighted clinical magnetic resonance images. This is particularly important on low-field-strength systems, which are not sensitive to the T2 shortening effects of paramagnetic intracellular deoxyhemoglobin.
在0.23和4.7特斯拉的磁场强度下，对氧饱和度为43%-73%、血细胞比容为18%-100%的脱氧血液样本进行T2值测量。血细胞比容的增加在两种磁场强度下均导致T2显著降低。细胞裂解在两种磁场强度下均未消除T2效应。作者得出结论，与脑相比，在T2加权临床磁共振图像上，回缩性血凝块形成导致的血红蛋白浓度增加是急性出血低信号表现的一个原因。这在低场强系统中尤为重要，因为低场强系统对顺磁性细胞内脱氧血红蛋白的T2缩短效应不敏感。
