Line scan diffusion spectrum of the denervated rat skeletal muscle

Abstract

Purpose: To detect the earlier changes of the skeletal muscle of rats after peripheral nerve injury by measuring the apparent diffusion coefficient (ADC) on diffusion MR spectroscopy. Materials and Methods:The posterior tibial nerve was transected in six rats (nerve transection group) and was only dissected in six rats (control group). At one, three, five, seven, 14, and 28 days after the surgery, both the T2 value and the ADC of gastrocnemius muscle were measured using a line-scan diffusion spectrum on a 1.5T clinical MR imager on both groups. Results:In the nerve transection group, the T2 ratio compared to the contralateral side increased gradually over four weeks after the transection, while the ADC ratio increased right after the surgery and began to decrease at five days. Four weeks after the transection, the ADC ratio returned to normal while the T2 ratio stayed at a high value. The control group indicated an almost constant T2 and ADC ratio during the experimental periods. Conclusion:The ADC of the skeletal muscle increased quickly after the transection of the dominant peripheral nerve and was detectable one day after the surgery. Diffusion MRI can be a useful tool for early detection of peripheral nerve injury instead of T2-weighted MRI or electromyography (EMG).

Techniques and applications of skeletal muscle diffusion tensor imaging: A review

“…c,d). These results are in agreement with the study by Yamabe et al, who found a significantly elevated FA in denervated muscles of rats in the chronic phase.…”

Diffusion tensor imaging and T2 mapping in early denervated skeletal muscle in rats

“…These events are thought to cause high signal intensity abnormality on T2‐weighted image. In experimental studies, MR signal abnormalities were reported variously from within 24 h to several days . Different nerve injury patterns could lead to various results .…”

“…Recently various MRI techniques have been developed to evaluate skeletal muscle changes after nerve injury. Diffusion tensor imaging (DTI) using a series of diffusion‐weighted (DW) images can provide structural characterization of anisotropic muscle tissues by assessing the degree and the directionality of water diffusion in tissue . DTI indices such as fractional anisotropy (FA), relative anisotropy (RA), and apparent diffusion coefficient (ADC) have been used in the evaluation of skeletal muscle injury, denervation, ischemia, dystrophy, and inflammation .…”

“…Diffusion tensor imaging (DTI) using a series of diffusionweighted (DW) images can provide structural characterization of anisotropic muscle tissues by assessing the degree and the directionality of water diffusion in tissue. 2,3 DTI indices such as fractional anisotropy (FA), relative anisotropy (RA), and apparent diffusion coefficient (ADC) have been used in the evaluation of skeletal muscle injury, denervation, ischemia, dystrophy, and inflammation. [2][3][4][5][6] Increased T2 values were observed in denervated skeletal muscle after nerve injury 7 as well as in neuromuscular disorder.…”

“…2,3 DTI indices such as fractional anisotropy (FA), relative anisotropy (RA), and apparent diffusion coefficient (ADC) have been used in the evaluation of skeletal muscle injury, denervation, ischemia, dystrophy, and inflammation. [2][3][4][5][6] Increased T2 values were observed in denervated skeletal muscle after nerve injury 7 as well as in neuromuscular disorder. 8 Quan-tification of T2 values using T2 mapping scan has been used as an objective method to evaluate muscle involvement and to monitor the therapeutic effects in people with neuromuscular disorder.…”