Quantitative Ultrasound Imaging to Assess the Biceps Brachii Muscle in Chronic Post-Stroke Spasticity: Preliminary Observation

Abstract

We prospectively investigated the feasibility of using quantitative ultrasound imaging (QUI) to assess the biceps brachii muscle (BBM) in individuals with chronic post-stroke spasticity. To quantify muscle echogenicity and stiffness, we measured QUI parameters (gray-scale pixel value and shear wave velocity [SWV, m/s]) of the BBM in three groups: 16 healthy BBMs; 12 post-stroke, non-spastic BBMs; and 12 post-stroke, spastic BBMs. The QUI results were compared with the Modified Ashworth Scale and Tardieu Scale. A total of 20 SWVs were measured in each BBM, once at elbow in 90° flexion and again at maximally achievable extension using acoustic radiation force impulse imaging. BBM pixel value was measured in gray-scale images captured at 90° elbow flexion using ImageJ software. Statistical analyses included analysis of variance for examining the difference in SWV and pixel values among the three groups; Bonferroni correction for testing the difference in SWV and pixel values in a paired group; t-test for examining the difference in SWV values measured at two elbow angles; and Pearson correlation coefficient for analyzing the correlation of QUI to Modified Ashworth Scale and Tardieu Scale. SWV significantly differed between spastic BBMs and non-spastic or healthy BBMs. For pixel values, each of the three groups significantly differed from the others at elbow 90° flexion. The difference in SWV measured between the two elbow angles was also significant (p < 0.01). A strong negative correlation was found between SWV and passive range of motion (R2 = −0.88, p < 0.0001) in spastic upper limbs. These results suggest that the use of QUI is feasible in quantitative assessment of spastic BBM.