MR Imaging in the Diagnosis of Denervated and Reinnervated Skeletal Muscles

Experimental Study in Rats

Yoshito Kikuchi, Toshiyasu Nakamura, Shinichiro Takayama, Yukio Horiuchi, Yoshiaki Toyama

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

PURPOSE: To describe the magnetic resonance (MR) imaging findings of denervation and reinnervation of skeletal muscles in rats. MATERIALS AND METHODS: The posterior tibial nerve was transected in 48 rats (nerve section group) and was repaired just after transection in another 48 rats (nerve repair group). At 2, 4, 6, and 8 weeks after surgery, changes in the area and signal intensity of the gastrocnemius muscle on T1- and T2-weighted MR images in vivo (four rats in each group) and T1s and T2s were analyzed in vitro in both groups (20 rats each) and compared with electromyographic findings. Water volume content and extracellular fluid space of the muscle in vitro were also examined in both groups (24 rats each). Four rats were used as controls for in vitro analysis. RESULTS: At T2-weighted MR imaging, the muscle showed continuously high signal intensity in the nerve section group. In the nerve repair group, the signal intensity was high until 4 weeks, when it recovered. Increases in signal intensity on T2-weighted MR images and T2s were seen in the nerve section group throughout the study period. In the nerve repair group, increased signal intensity on T2-weighted MR images was noted at 2 and 4 weeks and significantly returned to normal at 6 weeks (P < .014), just after the detection of the M wave at electromyography. T2 increased at 2 weeks, then decreased significantly at 4 weeks (P = .012). Extracellular fluid space significantly increased in the nerve section group at all measurement times and in the nerve repair group at 2 and 4 weeks, then it decreased after 6 weeks (P < .003), which is parallel to the change in signal intensity on T2-weighted MR images, although there was little change in total water volume content in either group. CONCLUSION: Changes in signal intensity on T2-weighted MR images that are related to denervation may result from an increase of extracellular fluid space. MR imaging clearly demonstrates that changes in rat skeletal muscle are reversed when the nerve heals and reinnervation proceeds.

Original languageEnglish
Pages (from-to)861-867
Number of pages7
JournalRadiology
Volume229
Issue number3
DOIs
Publication statusPublished - 2003 Dec

Fingerprint

Skeletal Muscle
Magnetic Resonance Imaging
Magnetic Resonance Spectroscopy
Extracellular Fluid
Extracellular Space
Denervation
Muscles
Tibial Nerve
Water
Electromyography
In Vitro Techniques

Keywords

  • Animals
  • Experimental study
  • Magnetic resonance (MR), experimental studies
  • Muscles, denervation
  • Muscles, gastrocnemius
  • Muscles, MR

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology

Cite this

MR Imaging in the Diagnosis of Denervated and Reinnervated Skeletal Muscles : Experimental Study in Rats. / Kikuchi, Yoshito; Nakamura, Toshiyasu; Takayama, Shinichiro; Horiuchi, Yukio; Toyama, Yoshiaki.

In: Radiology, Vol. 229, No. 3, 12.2003, p. 861-867.

Research output: Contribution to journalArticle

Kikuchi, Y, Nakamura, T, Takayama, S, Horiuchi, Y & Toyama, Y 2003, 'MR Imaging in the Diagnosis of Denervated and Reinnervated Skeletal Muscles: Experimental Study in Rats', Radiology, vol. 229, no. 3, pp. 861-867. https://doi.org/10.1148/radiol.2293020904
Kikuchi, Yoshito ; Nakamura, Toshiyasu ; Takayama, Shinichiro ; Horiuchi, Yukio ; Toyama, Yoshiaki. / MR Imaging in the Diagnosis of Denervated and Reinnervated Skeletal Muscles : Experimental Study in Rats. In: Radiology. 2003 ; Vol. 229, No. 3. pp. 861-867.
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AU - Kikuchi, Yoshito

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AU - Horiuchi, Yukio

AU - Toyama, Yoshiaki

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N2 - PURPOSE: To describe the magnetic resonance (MR) imaging findings of denervation and reinnervation of skeletal muscles in rats. MATERIALS AND METHODS: The posterior tibial nerve was transected in 48 rats (nerve section group) and was repaired just after transection in another 48 rats (nerve repair group). At 2, 4, 6, and 8 weeks after surgery, changes in the area and signal intensity of the gastrocnemius muscle on T1- and T2-weighted MR images in vivo (four rats in each group) and T1s and T2s were analyzed in vitro in both groups (20 rats each) and compared with electromyographic findings. Water volume content and extracellular fluid space of the muscle in vitro were also examined in both groups (24 rats each). Four rats were used as controls for in vitro analysis. RESULTS: At T2-weighted MR imaging, the muscle showed continuously high signal intensity in the nerve section group. In the nerve repair group, the signal intensity was high until 4 weeks, when it recovered. Increases in signal intensity on T2-weighted MR images and T2s were seen in the nerve section group throughout the study period. In the nerve repair group, increased signal intensity on T2-weighted MR images was noted at 2 and 4 weeks and significantly returned to normal at 6 weeks (P < .014), just after the detection of the M wave at electromyography. T2 increased at 2 weeks, then decreased significantly at 4 weeks (P = .012). Extracellular fluid space significantly increased in the nerve section group at all measurement times and in the nerve repair group at 2 and 4 weeks, then it decreased after 6 weeks (P < .003), which is parallel to the change in signal intensity on T2-weighted MR images, although there was little change in total water volume content in either group. CONCLUSION: Changes in signal intensity on T2-weighted MR images that are related to denervation may result from an increase of extracellular fluid space. MR imaging clearly demonstrates that changes in rat skeletal muscle are reversed when the nerve heals and reinnervation proceeds.

AB - PURPOSE: To describe the magnetic resonance (MR) imaging findings of denervation and reinnervation of skeletal muscles in rats. MATERIALS AND METHODS: The posterior tibial nerve was transected in 48 rats (nerve section group) and was repaired just after transection in another 48 rats (nerve repair group). At 2, 4, 6, and 8 weeks after surgery, changes in the area and signal intensity of the gastrocnemius muscle on T1- and T2-weighted MR images in vivo (four rats in each group) and T1s and T2s were analyzed in vitro in both groups (20 rats each) and compared with electromyographic findings. Water volume content and extracellular fluid space of the muscle in vitro were also examined in both groups (24 rats each). Four rats were used as controls for in vitro analysis. RESULTS: At T2-weighted MR imaging, the muscle showed continuously high signal intensity in the nerve section group. In the nerve repair group, the signal intensity was high until 4 weeks, when it recovered. Increases in signal intensity on T2-weighted MR images and T2s were seen in the nerve section group throughout the study period. In the nerve repair group, increased signal intensity on T2-weighted MR images was noted at 2 and 4 weeks and significantly returned to normal at 6 weeks (P < .014), just after the detection of the M wave at electromyography. T2 increased at 2 weeks, then decreased significantly at 4 weeks (P = .012). Extracellular fluid space significantly increased in the nerve section group at all measurement times and in the nerve repair group at 2 and 4 weeks, then it decreased after 6 weeks (P < .003), which is parallel to the change in signal intensity on T2-weighted MR images, although there was little change in total water volume content in either group. CONCLUSION: Changes in signal intensity on T2-weighted MR images that are related to denervation may result from an increase of extracellular fluid space. MR imaging clearly demonstrates that changes in rat skeletal muscle are reversed when the nerve heals and reinnervation proceeds.

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