Helms G
MR Research Center, Karolinska Hospital, Karolinska Institutet, Stockholm, Sweden.
Magn Reson Med. 2001 Aug;46(2):256-63. doi: 10.1002/mrm.1186.
The effect of edema on metabolic changes in contrast-enhancing multiple sclerosis lesions was studied by combining quantification of proton MR spectra with segmentation of the volume-of-interest, which was based on biexponential T(2) relaxation. All lesions showed a second component (s(long)) with a longer T(2) (185-450 ms), which was increased compared to healthy controls. Regression analysis indicated that s(long) replaces the short-T(2) component and total creatine. Since the water content was close to 100%, s(long) was used to correct for an increase in extracellular space. This compensated for the apparent loss of creatine and rendered cholines markedly increased, as observed in animals with experimental allergic encephalomyelitis. Total N-acetyl aspartate (NAA) concentration was inversely correlated with s(long) and between 34-70% of its average reduction was assigned to edema. Thus, NAA loss exceeded cellular loss. Assessment of varying degrees of edema may be especially beneficial for quantitative longitudinal studies.
通过将质子磁共振波谱定量与基于双指数T(2)弛豫的感兴趣体积分割相结合，研究了水肿对对比增强型多发性硬化病变代谢变化的影响。所有病变均显示出具有较长T(2)（185 - 450毫秒）的第二个成分（s(long)），与健康对照相比有所增加。回归分析表明，s(long)取代了短T(2)成分和总肌酸。由于水含量接近100%，s(long)用于校正细胞外间隙的增加。这补偿了肌酸的明显损失，并使胆碱明显增加，这与实验性变应性脑脊髓炎动物中观察到的情况一致。总N-乙酰天门冬氨酸（NAA）浓度与s(long)呈负相关，其平均降低的34 - 70%归因于水肿。因此，NAA的损失超过了细胞损失。评估不同程度的水肿对于定量纵向研究可能特别有益。
