M. Ishikawa et al., Quantification of masseter muscle deformation during palpation using MRI and image-analysis procedure, INT J PROST, 14(4), 2001, pp. 367-373
Purpose: The aim of this study was to quantify masseter muscle deformation
during palpation and to discuss the clinical significance of muscle palpati
on using magnetic resonance imaging (MRI) and the image-analysis procedure.
Materials and Methods: Subjects were 10 male volunteers with a mean age of
26.8 years. MRIs were taken under two muscle conditions: compressed and no
ncompressed (control). By superimposing a compressed image on a noncompress
ed image, muscle deformation (the cross-sectional area, length of the surro
unding area, thickness, circular convolution, compressed point, and anterio
r and posterior extension) was measured. Results: The cross-sectional area
of the masseter muscle was diminished by 14%, circular convolution of the m
uscle was reduced by 31%, the length of the surrounding area was enlarged b
y 11%, and the thickness of the muscle was reduced by 6.7 mm because of com
pressing. Thus, the masseter muscle was compressed. An uneven stretch of th
e muscle caused by compression was observed at the same time. The anterior
portion of the masseter muscles extended on average 10%, with great individ
ual differences. On the other hand, posterior extension (3%) and its indivi
dual differences were small. Conclusion: The method used made it possible t
o quantify masseter muscle deformation. By compressing, the masseter muscle
s were deformed especially in the anterior direction but with great individ
ual differences.