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Updated: May 16, 2026
Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease
Published on: December 18, 2016
Correlation between pennation angle and image quality of skeletal muscle fibre tractography using deterministic
Yoshikazu Okamoto1, Toru Okamoto, Kujiraoka Yuka
1Department of Radiology, Institute of Clinical Medicine, University of Tsukuba Hospital, Tsukuba, Ibaraki, Japan. yokamoto@md.tsukuba.ac.jp
Introduction:
The aim of this study was to ascertain whether a correlation existed between muscle pennation angle and the ability to successfully perform tractography of the lower leg muscle fibres with deterministic diffusion tensor imaging (DTI) in normal volunteers.
Methods:
Fourteen volunteers aged 20-39 (mean 28.2 years old) were recruited. All volunteers were scanned using DTI, and six fibre tractographs were constructed from one lower leg of each volunteer, and the 'fibre density' was calculated in each of the tractographs. The pennation angle is the angle formed by the muscle fibre and the aponeurosis. The average pennation angle (AVPA) and standard deviation of the pennation angle (SDPA) were also measured for each muscle by ultrasonography in the same region as the MRI scan. For all 84 tractography images, the correlation coefficient between the fibre density and AVPA or SDPA was calculated.
Results:
Fibre density and AVPA showed a moderate negative correlation (R = -0.72), and fibre density and SDPA showed a weak negative correlation (R = -0.47). With respect to comparisons within each muscle, AVPA and fibre density showed a moderate negative correlation in the gastrocnemius lateralis muscle (R = -0.57).
Conclusions:
Our data suggest that a larger, more variable pennation angle resulted in worse skeletal muscle tractography using deterministic DTI.
