Duong T Q, Ackerman J J, Ying H S, Neil J J
Department of Chemistry, Washington University, St. Louis, Missouri, USA.
Magn Reson Med. 1998 Jul;40(1):1-13. doi: 10.1002/mrm.1910400102.
The biophysical mechanism(s) underlying diffusion-weighted MRI contrast following brain injury remains to be elucidated. Although it is generally accepted that water apparent diffusion coefficient (ADC) decreases after brain injury, it is unknown whether this is associated with a decrease in intracellular or extracellular water displacement, or both. To address this question, 2-[19F]luoro-2-deoxyglucose-6-phosphate (2FDG-6P) was employed as a compartment-specific marker in normal and globally ischemic rat brain. Through judicious choice of routes of administration, 2FDG-6P was confined to the intra- or extracellular space. There was no statistical difference between intra- and extracellular 2FDG-6P ADCs in normal or in globally ischemic brain (P > 0.16), suggesting that water ADCs in both compartments are similar. However, ischemia did result in a 40% ADC decrease in both compartments (P < 0.001). Assuming that 2FDG-6P reflects water motion, this study shows that water ADC decreases in both spaces after ischemia, with the reduction of intracellular water motion being the primary source of diffusion-weighted contrast.
脑损伤后扩散加权磁共振成像对比度的生物物理机制仍有待阐明。虽然人们普遍认为脑损伤后水的表观扩散系数（ADC）会降低，但尚不清楚这是否与细胞内或细胞外水位移的减少有关，还是两者都有关。为了解决这个问题，2-[19F]氟-2-脱氧葡萄糖-6-磷酸（2FDG-6P）被用作正常和全脑缺血大鼠脑内的特定隔室标记物。通过明智地选择给药途径，2FDG-6P被限制在细胞内或细胞外空间。正常或全脑缺血脑中细胞内和细胞外2FDG-6P的ADC之间没有统计学差异（P>0.16），表明两个隔室中的水ADC相似。然而，缺血确实导致两个隔室中的ADC均降低了40%（P<0.001）。假设2FDG-6P反映水的运动，这项研究表明缺血后两个空间中的水ADC均降低，细胞内水运动的减少是扩散加权对比度的主要来源。
