Feng Shu, Chen Daniel, Kushmerick Martin, Lee Donghoon
Department of Bioengineering, University of Washington, Seattle, Washington, USA.
J Magn Reson Imaging. 2014 Oct;40(4):779-88. doi: 10.1002/jmri.24417. Epub 2013 Oct 31.
To test the ability of different magnetic resonance imaging (MRI) modalities to discriminate the time course of damage and regeneration in a model of acute, toxin-induced muscle damage.
We analyzed the time course of tissue and cellular changes in mouse lower limb musculature following localized injection of myotoxin by T2 , magnetization transfer (MT), and diffusion-weighted MRI. We also used T1 -weighted imaging to measure leg muscle volume. In addition, postmortem histological analysis of toxin-injected muscles was compared to uninjected controls.
The damages detected by the MRI modalities are transient and recover within 3 weeks. Muscle water diffusivity and edema measured by leg volume increased within the first hours after injection of the toxin. The rate constant for volume increase was 0.65 ± 0.11 hr(-1) , larger than the increase in T2 (0.045 ± 0.013 hr(-1) ) and change in MT ratio (0.028 ± 0.021 hr(-1) ). During repair phase, the rate constants were much smaller: 0.022 ± 0.004 hr(-1) , 0.013 ± 0.0019 hr(-1) and 0.0042 ± 0.0016 hr(-1) for volume, T2 , and MT ratio, respectively. Histological analyses confirmed the underlying cellular changes that matched the progression of MR images.
The kinetics of change in the MRI measurements during the progression of damage and repair shows MRI modalities can be used to distinguish these processes.
在急性毒素诱导的肌肉损伤模型中，测试不同磁共振成像（MRI）模式区分损伤和再生时间进程的能力。
我们通过T2、磁化传递（MT）和扩散加权MRI分析了小鼠下肢肌肉组织在局部注射肌毒素后的组织和细胞变化时间进程。我们还使用T1加权成像测量腿部肌肉体积。此外，将注射毒素的肌肉的死后组织学分析与未注射的对照进行比较。
MRI模式检测到的损伤是短暂的，在3周内恢复。注射毒素后的最初几小时内，通过腿部体积测量的肌肉水扩散率和水肿增加。体积增加的速率常数为0.65±0.11小时-1，大于T2的增加（0.045±0.013小时-1）和MT比率的变化（0.028±0.021小时-1）。在修复阶段，速率常数要小得多：体积、T2和MT比率的速率常数分别为0.022±0.004小时-1、0.013±0.0019小时-1和0.0042±0.0016小时-1。组织学分析证实了与MR图像进展相匹配的潜在细胞变化。
在损伤和修复过程中，MRI测量的变化动力学表明MRI模式可用于区分这些过程。
