Department of Biomedical Engineering, Marquette University & Medical College of Wisconsin, Milwaukee, WI, United States of America; Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States of America.
Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States of America.
Magn Reson Imaging. 2021 May;78:42-51. doi: 10.1016/j.mri.2021.02.004. Epub 2021 Feb 6.
In the traumatically injured spinal cord, decreased perfusion is believed to contribute to secondary tissue damage beyond the primary mechanical impact, and restoration of perfusion is believed to be a promising therapeutic target. However, methods to monitor spinal cord perfusion non-invasively are limited. Perfusion magnetic resonance imaging (MRI) techniques established for the brain have not been routinely adopted to the spinal cord. The purpose of this study was to examine the relationship between spinal cord blood flow (SCBF) and injury severity in a rat thoracic spinal cord contusion injury (SCI) model using flow-sensitive alternating inversion recovery (FAIR) with two variants of the label position. SCBF as a marker of severity was compared to T mapping and to spinal cord-optimized diffusion weighted imaging (DWI) with filtered parallel apparent diffusion coefficient. Thirty-eight rats underwent a T10 contusion injury with varying severities (8 sham; 10 mild; 10 moderate; 10 severe) with MRI performed at 1 day post injury at the lesion site and follow-up neurological assessments using the Basso, Beattie, Bresnahan (BBB) locomotor scoring up to 28 days post injury. Using whole-cord regions of interest at the lesion epicenter, SCBF was decreased with injury severity and had a significant correlation with BBB scores at 28 days post injury. Importantly, estimates of arterial transit times (ATT) in the injured spinal cord were not altered after injury, which suggests that FAIR protocols optimized to measure SCBF provide more value in the context of acute traumatic injury to the cord. T-relaxation time constants were strongly related to injury severity and had a larger extent of changes than either SCBF or DWI measures. These findings suggest that perfusion decreases in the spinal cord can be monitored non-invasively after injury, and multi-parametric MRI assessments of perfusion, diffusion, and relaxation capture unique features of the pathophysiology of preclinical injury.
在创伤性脊髓损伤中，灌注减少被认为是导致原发性机械损伤以外的继发性组织损伤的原因，恢复灌注被认为是有前途的治疗靶点。然而，非侵入性监测脊髓灌注的方法有限。用于大脑的灌注磁共振成像（MRI）技术尚未常规应用于脊髓。本研究旨在使用具有两种标记位置变体的血流敏感交替反转恢复（FAIR）技术，在大鼠胸段脊髓挫伤损伤（SCI）模型中检查脊髓血流（SCBF）与损伤严重程度之间的关系。将 SCBF 作为严重程度的标志物与 T 映射和脊髓优化的扩散加权成像（DWI）进行比较，后者使用带滤波的平行表观扩散系数。38 只大鼠接受了 T10 挫伤损伤，损伤程度不同（8 只假手术；10 只轻度；10 只中度；10 只重度），在损伤后 1 天在病变部位进行 MRI 检查，并在损伤后 28 天使用 Basso、Beattie、Bresnahan（BBB）运动评分进行后续神经学评估。使用病变中心的全脊髓 ROI，SCBF 随损伤严重程度降低，与损伤后 28 天的 BBB 评分有显著相关性。重要的是，损伤后脊髓的动脉渡越时间（ATT）估计值没有改变，这表明优化用于测量 SCBF 的 FAIR 方案在急性创伤性脊髓损伤的情况下提供了更多的价值。T 弛豫时间常数与损伤严重程度密切相关，其变化程度大于 SCBF 或 DWI 测量值。这些发现表明，损伤后可以非侵入性地监测脊髓灌注的减少，灌注、扩散和弛豫的多参数 MRI 评估可以捕获临床前损伤病理生理学的独特特征。
