Quantitative assessment of skeletal muscle activation using muscle functional MRI

Ryuta Kinugasa, Yasuo Kawakami, Tetsuo Fukunaga

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The purpose of the present study is to determine whether muscle functional MRI (mfMRI) can be used to obtain three-dimensional (3-D) images useful for evaluating muscle activity, and if so, to measure the distribution of muscle activity within a medial gastrocnemius (MG) muscle. Seven men performed 5 sets of 10 repetitions of a calf-raise exercise with additional 15% of body-weight load. Magnetic resonance images were obtained before and immediately after the exercise. To threshold images, only those pixels showing transverse relaxation time (T2) greater than the mean+1 S.D. of the entire regions of interest (ROIs) in the preexercise image and T2 lower than the mean+1 S.D. of the entire ROIs in the postexercise image were identified. The survived pixels showing T2 are defined as active muscle. Those thresholded images were 3-D reconstructed, and this was used to determine area of active muscle along transverse, longitudinal and vertical axes. At the exercise level used in the present study, the percentage volume of activated muscle in the MG was 62.8±4.5%. There was a significant correlation between percentage volume of activated muscle and integrated electromyography (r=.78, P<.05). Percentage areas of activated muscle were significantly larger in the medial than in the lateral region, in the anterior than in the posterior region and in the distal than in the proximal region (P<.05). These results suggest that mfMRI can be used to evaluate the muscle activity and to determine intramuscular variations of activity within skeletal muscle.

Original languageEnglish
Pages (from-to)639-644
Number of pages6
JournalMagnetic Resonance Imaging
Volume24
Issue number5
DOIs
Publication statusPublished - 2006 Jun

Fingerprint

skeletal muscle
muscles
Muscle
Skeletal Muscle
Chemical activation
activation
Muscles
physical exercise
Three-Dimensional Imaging
Exercise
pixels
electromyography
Pixels
body weight
calves
Electromyography
Magnetic resonance
magnetic resonance
Magnetic Resonance Spectroscopy
Relaxation time

Keywords

  • Activation
  • EMG
  • Human
  • Muscle
  • T2

ASJC Scopus subject areas

  • Biophysics
  • Clinical Biochemistry
  • Structural Biology
  • Radiology Nuclear Medicine and imaging
  • Condensed Matter Physics

Cite this

Quantitative assessment of skeletal muscle activation using muscle functional MRI. / Kinugasa, Ryuta; Kawakami, Yasuo; Fukunaga, Tetsuo.

In: Magnetic Resonance Imaging, Vol. 24, No. 5, 06.2006, p. 639-644.

Research output: Contribution to journalArticle

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