Caillé J M, Constant P, Billerey J, Renou A M
Comput Tomogr. 1978;2(2):63-8. doi: 10.1016/0363-8235(78)90004-2.
The cerebral blood volume (CBV) has been measured by transverse axial tomography. The attenuation coefficient of 100 "pixels" located in a well determined region was measured before and after injection of a contrast material (Telebrix 38). The attenuation coefficient of blood samples was measured by CT in a phantom. Blood samples were drawn before and after injection at the same time as the tomographic section (time: half rotation of the scanner). The volume was calculated by the (formula: see text). The values obtained with very early measurements (1--5 min after injection), were very close to those measured by other methods (3--5 ml/100 ml). For 5 patients, the CBV was measured by the same method at different times: 20 measures between 2 and 50 min after the injection. The CBV seemed to vary in function with time according to the equation: CBV in ML%: ate-bt + Vo (t = time in minutes: a = integration constant, a = 1.94; b = time constant, b = 0.089; Vo = real CBV). The apparent variation of CBV was the result of two factors related to the blood-brain barrier, (1) water movement from the extravascular space towards the intravascular space, related to the hyperosmolarity of the contrast medium. The variations of osmolarity and haematocrit values measured after contrast injection did confirm this hypothesis; and (2) iodine movement from the intravascular space towards the extravascular space, due to the toxicity of the material (hyperosmolarity, Na ions, etc). The measurement of CBV by CT is only possible if the contrast materials do not modify the blood-brain barrier. The use of actual materials allows the study of the blood-brain barrier behaviour and enables to make an estimate of the cerebral extra-cellular space. But CT is not a right method of CBV measurement with the contrast medium in use nowadays.
脑血容量（CBV）已通过横向轴向断层扫描进行测量。在注射造影剂（Telebrix 38）前后，对位于明确区域的100个“像素”的衰减系数进行了测量。通过CT在体模中测量血样的衰减系数。在断层扫描切片的同时（时间：扫描仪半旋转），在注射前后采集血样。通过（公式：见文本）计算体积。极早期测量（注射后1 - 5分钟）获得的值与其他方法测量的值（3 - 5 ml/100 ml）非常接近。对于5名患者，在不同时间通过相同方法测量CBV：注射后2至50分钟内进行了20次测量。CBV似乎根据以下方程随时间变化：CBV（以毫升百分比计）：ate - bt + Vo（t = 时间，以分钟为单位；a = 积分常数，a = 1.94；b = 时间常数，b = 0.089；Vo = 实际CBV）。CBV的明显变化是与血脑屏障相关的两个因素的结果，（1）水从血管外间隙向血管内间隙移动，这与造影剂的高渗性有关。造影剂注射后测量的渗透压和血细胞比容值的变化确实证实了这一假设；以及（2）由于材料的毒性（高渗性、钠离子等），碘从血管内间隙向血管外间隙移动。只有当造影剂不改变血脑屏障时，通过CT测量CBV才是可能的。使用实际材料可以研究血脑屏障的行为，并能够估计脑细胞外间隙。但对于目前使用的造影剂，CT并不是测量CBV的正确方法。
