Quantitative ultrasound of trapezius muscle involvement in myofascial pain: comparison of clinical and healthy population using texture analysis

Abstract

Purpose: Ultrasound is a non-invasive quantitative method to characterize sonographic textures of skeletal muscles. To date, there is no information available on the trapezius muscle. This study assessed the trapezius muscles of patients with myofascial pain compared with normal healthy participants.

Methods: The trapezius muscles of 15 healthy and 17 myofascial pain participants were assessed using B-mode ultrasound to obtain 120 images for healthy and 162 images from myofascial pain participants. Texture features such as blob area, count and local binary patterns (LBP) were calculated. Multi-feature classification and analysis were performed using principal component analysis (PCA) and MANOVA to determine whether there were statistical differences.

Results: We demonstrate the two principal components composed of a combination of LBP and blob parameters which explain 92.55% of the cumulative variance of our data set. In addition, blob characteristics were significantly different between healthy and myofascial pain participants.

Conclusion: Our study provides evidence that texture analysis techniques can differentiate between healthy and myofascial pain affected trapezius muscles. Further research is necessary to evaluate the nature of these differences.

Keywords: Myofascial pain; Quantitation; Texture analysis; Trapezius muscle; Ultrasound.

Conflict of interest statement

The authors and author institutions have no conflict of interest to declare. This includes financial or personal relationships, dual commitments, competing interests or competing loyalties.

Figures

Fig. 1

The B-mode Ultrasound gray-scale image of the upper trapezius muscle (a). b shows the selected region of interest for the blob analysis. The first round of identified blobs that have echo intensities outside the specified range is given by c. These blobs are filtered on the basis of their size using the specified area threshold. These residual blobs (shown in d) are counted and measured, generating Figs. 2 and 3. Scale: depth 2.0 cm

Fig. 2

Area of the computed blobs (in mm2), shown for the left and the right upper trapezius musculature, for each of the two operators (DK and SS). Kurtosis can result in a higher SD than the mean

Fig. 3

Number of the computed blobs (per mm2) shown for the left and the right upper trapezius musculature, for each of the two operators (DK and SS). Kurtosis can result in a higher SD than the mean

Fig. 4

Local binary pattern example showing the various matrices that are created during the calculation of LBP. a The central pixel echo intensity is used to calculated the values of the surrounding pixels (in a circular pattern) to generate the matrix in b. Then, the values are multiplied by the matrix in c to obtain the final matrix in d