Murata Yoshihiro, Sakatani Kaoru, Hoshino Tatsuya, Fujiwara Norio, Kano Tsuneo, Nakamura Shin, Katayama Yoichi
Department of Neurosurgery, Nihon University School of Medicine, 30-1, Oyaguchi-Kamimachi, Itabashi-ku, Tokyo 173-8610, Japan.
Stroke. 2006 Oct;37(10):2514-20. doi: 10.1161/01.STR.0000239698.50656.3b. Epub 2006 Aug 31.
To evaluate the mechanisms of failure of blood oxygenation level-dependent (BOLD) imaging in stroke, we compared the evoked cerebral blood oxygenation (CBO) responses and activation volumes (AVs) of BOLD functional MRI (fMRI) in chronic stroke patients with moderate and severe cerebral ischemia.
We measured the evoked CBO responses in the primary sensorimotor cortex (PSMC) by means of near-infrared spectroscopy during contralateral motor tasks. We compared the AV of BOLD-functional MRI in the PSMC on the nonlesion and lesion sides. Single-photon emission computed tomography was used to classify ischemic status as moderate (slight reduction of regional cerebral blood flow and cerebrovascular reserve capacity [CVRC]) or severe (marked reduction of regional cerebral blood flow and CVRC; ie, misery perfusion).
In age-matched controls, deoxyhemoglobin concentration decreased with concomitant increases in oxyhemoglobin and total hemoglobin concentrations during activation. The PSMC on the nonlesion side exhibited a normal CBO response pattern. On the lesion side, moderate cerebral ischemia did not affect the CBO response pattern, but severe cerebral ischemia caused an increase of deoxyhemoglobin during the task, associated with increases of oxyhemoglobin and total hemoglobin. Moderate cerebral ischemia induced only a slight reduction of the AV on the lesion side; however, severe cerebral ischemia markedly reduced the AV on the lesion side. The BOLD signal did not change in some areas of the PSMC on the lesion side in severe cerebral ischemia, whereas it tended to decrease in other areas during the tasks.
Misery perfusion caused a marked reduction of the AV on BOLD imaging, associated with an increase of deoxyhemoglobin concentration during activation. BOLD-fMRI investigations of stroke patients should be performed while giving consideration to baseline circulatory status. Functional near-infrared spectroscopy could be an alternative means to assess the CVRC.
为评估血氧水平依赖（BOLD）成像在中风中失效的机制，我们比较了中度和重度脑缺血慢性中风患者的诱发脑血氧合（CBO）反应以及BOLD功能磁共振成像（fMRI）的激活体积（AV）。
我们在对侧运动任务期间，通过近红外光谱法测量初级感觉运动皮层（PSMC）的诱发CBO反应。我们比较了PSMC在非病变侧和病变侧的BOLD功能磁共振成像的AV。使用单光子发射计算机断层扫描将缺血状态分类为中度（局部脑血流量和脑血管储备能力[CVRC]轻度降低）或重度（局部脑血流量和CVRC显著降低；即灌注不良）。
在年龄匹配的对照组中，激活期间脱氧血红蛋白浓度降低，同时氧合血红蛋白和总血红蛋白浓度增加。非病变侧的PSMC表现出正常的CBO反应模式。在病变侧，中度脑缺血不影响CBO反应模式，但重度脑缺血导致任务期间脱氧血红蛋白增加，同时氧合血红蛋白和总血红蛋白增加。中度脑缺血仅导致病变侧AV略有降低；然而，重度脑缺血显著降低了病变侧的AV。在重度脑缺血时，病变侧PSMC的某些区域BOLD信号未改变，而在任务期间其他区域BOLD信号趋于降低。
灌注不良导致BOLD成像的AV显著降低，与激活期间脱氧血红蛋白浓度增加相关。对中风患者进行BOLD-fMRI研究时应考虑基线循环状态。功能近红外光谱法可能是评估CVRC的另一种方法。
