Pierce A R, Lo E H, Mandeville J B, Gonzalez R G, Rosen B R, Wolf G L
Center for Imaging and Pharmaceutical Research, Massachusetts General Hospital, Boston, USA.
J Cereb Blood Flow Metab. 1997 Feb;17(2):183-90. doi: 10.1097/00004647-199702000-00008.
The aim of this study was to examine the quantitative relationship between changes in apparent diffusion coefficient (ADC) and transverse relaxivity (delta R2*) measurements of relative perfusion deficits within the gradients of a focal ischemic insult. Sixty minutes after permanent occlusion of the middle cerebral artery, rats (n = 7) were subjected to spin echo diffusion-weighted scans followed by fast low-angle shot (FLASH) perfusion-sensitive scans. Diffusion-weighted images showed clear ischemic lesions in the affected basal ganglia and cortex. Ischemic deficits were demonstrated as a decrease in first-pass transit of injected boluses of gadodiamide. ADC maps were generated and regions of interest (ROIs) were obtained to span the range of ADC reductions from the lesion center or core to the periphery or penumbra. Corresponding ROIs from the bolus injection images were used to calculate perfusion indexes relative to contralateral levels as ratios of delta R2* integrals and ratios of delta R2* peak values. In all animals, the degree of ADC reductions was related to the degree of delta R2* perfusion deficits, ranging from severe ischemia in the core of the lesion to intermediate and moderate changes toward the lesion periphery. In the ischemic periphery, ADC reductions were linearly correlated with delta R2* peak ratios. However, no significant correlation was found between ADC reductions and delta R2* integral ratios. These data suggest that magnetic resonance measurements of ADC and delta R2* peak ratios can be used to quantitatively assess the variable gradients in focal ischemia, including potentiallyn critical areas at risk in the ischemic periphery.
本研究的目的是检测局灶性缺血损伤梯度范围内相对灌注缺损的表观扩散系数（ADC）变化与横向弛豫率（δR2*）测量值之间的定量关系。大脑中动脉永久性闭塞60分钟后，对大鼠（n = 7）进行自旋回波扩散加权扫描，随后进行快速低角度激发（FLASH）灌注敏感扫描。扩散加权图像显示受影响的基底神经节和皮质有明显的缺血性病变。缺血性缺损表现为注射的钆双胺首次通过时的减少。生成ADC图，并获取感兴趣区域（ROI），以覆盖从病变中心或核心到周边或半暗带的ADC降低范围。来自团注图像的相应ROI用于计算相对于对侧水平的灌注指数，作为δR2积分比值和δR2峰值比值。在所有动物中，ADC降低程度与δR2灌注缺损程度相关，范围从病变核心的严重缺血到病变周边的中度和轻度变化。在缺血周边，ADC降低与δR2峰值比值呈线性相关。然而，ADC降低与δR2积分比值之间未发现显著相关性。这些数据表明，ADC和δR2峰值比值的磁共振测量可用于定量评估局灶性缺血中的可变梯度，包括缺血周边潜在的关键危险区域。
