McMillan Alan B, Shi Da, Pratt Stephen J P, Lovering Richard M
Department of Diagnostic Radiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
J Biomed Biotechnol. 2011;2011:970726. doi: 10.1155/2011/970726. Epub 2011 Nov 15.
The purpose of this study was to determine if variables calculated from diffusion tensor imaging (DTI) would serve as a reliable marker of damage after a muscle strain injury in dystrophic (mdx) and wild type (WT) mice. Unilateral injury to the tibialis anterior muscle (TA) was induced in vivo by 10 maximal lengthening contractions. High resolution T1- and T2-weighted structural MRI, including T2 mapping and spin echo DTI was acquired on a 7T small animal MRI system. Injury was confirmed by a significant loss of isometric torque (85% in mdx versus 42% in WT). Greater increases in apparent diffusion coefficient (ADC), axial, and radial diffusivity (AD and RD) of the injured muscle were present in the mdx mice versus controls. These changes were paralleled by decreases in fractional anisotropy (FA). Additionally, T2 was increased in the mdx mice, but the spatial extent of the changes was less than those in the DTI parameters. The data suggest that DTI is an accurate indicator of muscle injury, even at early time points where the MR signal changes are dominated by local edema.
本研究的目的是确定从扩散张量成像（DTI）计算得出的变量是否可作为营养不良（mdx）小鼠和野生型（WT）小鼠肌肉拉伤损伤后损伤的可靠标志物。通过10次最大程度的拉长收缩在体内诱导单侧胫前肌（TA）损伤。在7T小动物MRI系统上采集高分辨率T1加权和T2加权结构MRI，包括T2图谱和自旋回波DTI。通过等长扭矩显著降低（mdx小鼠降低85%，WT小鼠降低42%）来确认损伤。与对照组相比，mdx小鼠受伤肌肉的表观扩散系数（ADC）、轴向扩散率和径向扩散率（AD和RD）有更大程度的增加。这些变化与各向异性分数（FA）的降低同时出现。此外，mdx小鼠的T2增加，但变化的空间范围小于DTI参数的变化范围。数据表明，即使在MR信号变化主要由局部水肿主导的早期时间点，DTI也是肌肉损伤的准确指标。
