Pineiro R, Pendlebury S T, Smith S, Flitney D, Blamire A M, Styles P, Matthews P M
Oxford Centre for Functional MRI of the Brain (FMRIB), John Radcliffe Hospital, Oxford, UK.
Stroke. 2000 Mar;31(3):672-9. doi: 10.1161/01.str.31.3.672.
Infarct size on T2-weighted MRI correlates only modestly with outcome, particularly for small strokes. This may be largely because of differences in the locations of infarcts and consequently in the functional pathways that are damaged. To test this hypothesis quantitatively, we developed a "mask" of the corticospinal pathway to determine whether the extent of stroke intersection with the pathway would be more closely related to clinical motor deficit and axonal injury in the descending motor pathways than total stroke lesion volume.
Eighteen patients were studied > or =1 month after first ischemic stroke that caused a motor deficit by use of brain T2-weighted imaging, MR spectroscopic (MRS) measurements of the neuronal marker compound N-acetyl aspartate in the posterior limb of the internal capsule, and motor impairment and disability measures. A corticospinal mask based on neuroanatomic landmarks was generated from a subset of the MRI data. The maximum proportion of the cross-sectional area of this mask occupied by stroke was determined for each patient after all brain images were transformed into a common stereotaxic brain space.
There was a significant linear relationship between the maximum proportional cross-sectional area of the corticospinal mask occupied by stroke and motor deficit (r(2)=0.82, P<0.001), whereas the relationship between the total stroke volume and motor deficit was better described by a cubic curve (r(2)=0.76, P<0.001). Inspection of the data plots showed that the total stroke volume discriminated poorly between smaller strokes with regard to the extent of associated motor deficit, whereas the maximum proportion of the mask cross-sectional area occupied by stroke appeared to be a more discriminatory marker of motor deficit and also N-acetyl aspartate reduction.
Segmentation of functional motor pathways on MRI allows estimation of the extent of damage specifically to that pathway by the stroke lesion. The extent of stroke intersection with the motor pathways was more linearly related to the magnitude of motor deficit than total lesion volume and appeared to be a better discriminator between small strokes with regard to motor deficit. This emphasizes the importance of the anatomic relationship of the infarct to local structures in determining functional impairment. Prospective studies are necessary to assess whether this approach would allow improved early estimation of prognosis after stroke.
T2加权磁共振成像（MRI）上的梗死灶大小与预后的相关性不大，尤其是对于小卒中而言。这可能主要是因为梗死灶位置不同，进而导致受损功能通路存在差异。为了定量验证这一假设，我们绘制了皮质脊髓束通路的“模板”，以确定卒中与该通路的交叉范围是否比总的卒中病变体积更能紧密地反映临床运动功能缺损及下行运动通路中的轴突损伤情况。
对18例首次发生缺血性卒中且导致运动功能缺损1个月及以上的患者进行研究，采用脑部T2加权成像、磁共振波谱（MRS）测量内囊后肢中神经元标志物化合物N-乙酰天门冬氨酸，并进行运动功能障碍及残疾程度评估。基于神经解剖学标志，从MRI数据子集中生成皮质脊髓束模板。在将所有脑部图像转换至一个通用的立体定向脑空间后，确定每位患者的卒中占据该模板横截面积的最大比例。
卒中占据皮质脊髓束模板的最大比例横截面积与运动功能缺损之间存在显著的线性关系（r² = 0.82，P < 0.001），而总的卒中体积与运动功能缺损之间的关系用三次曲线能更好地描述（r² = 0.76，P < 0.001）。数据图显示，在较小卒中中，总的卒中体积对于相关运动功能缺损程度的区分能力较差，而卒中占据模板横截面积的最大比例似乎是运动功能缺损及N-乙酰天门冬氨酸减少的更具区分性的标志物。
通过MRI对功能性运动通路进行分割，可以估计卒中病变对该通路的特异性损伤程度。卒中与运动通路的交叉范围与运动功能缺损程度的线性关系比总的病变体积更为密切，并且在区分小卒中的运动功能缺损方面似乎是一个更好的指标。这强调了梗死灶与局部结构的解剖关系在确定功能障碍中的重要性。有必要进行前瞻性研究以评估这种方法是否能改善卒中后预后的早期评估。
