Conceptualization, Y.H. and M.N.; methodology, Y.H., M.N. and T.H.; validation, Y.H., M.N. and Y.S.; formal analysis, Y.H. and M.N.; investigation, Y.H., M.N. and Y.S.; resources, S.S. and J.U.; data curation, Y.H. and Y.S.; writing—original draft preparation, Y.H., M.N. and T.H.; writing—review and editing, Y.H., M.N., T.H. and M.A.; visualization, Y.H.; supervision, M.N., T.H. and M.A.; project administration, M.N.; All authors have read and agreed to the published version of the manuscript.

Figure 1. The decrease in SWV before and after BoNT-A injection was analyzed using independent samples t-test, dividing the group into two groups: (a) no change in R2 (Group 1); (b) change in R2 (Group 2).

Figure 1. The decrease in SWV before and after BoNT-A injection was analyzed using independent samples t-test, dividing the group into two groups: (a) no change in R2 (Group 1); (b) change in R2 (Group 2).

Figure 2. Measurement of the shear wave velocity. The ROI size was determined to be 10 mm (H) × 20 mm in the muscle belly: (a) measurement of SWV at rest of the GCM; (b) measurement of SWV at extension of the GCM. Left side shows the velocity of shear wave propagation; within the ROI, blue indicates slow propagation and red indicates fast. Right side, the time taken for the shear wave to propagate is indicated by contour lines (arrival time contour lines), which confirm that the shear wave is propagating through the tissue. Blue indicates a small arrival time and red indicates a large arrival time.

Figure 2. Measurement of the shear wave velocity. The ROI size was determined to be 10 mm (H) × 20 mm in the muscle belly: (a) measurement of SWV at rest of the GCM; (b) measurement of SWV at extension of the GCM. Left side shows the velocity of shear wave propagation; within the ROI, blue indicates slow propagation and red indicates fast. Right side, the time taken for the shear wave to propagate is indicated by contour lines (arrival time contour lines), which confirm that the shear wave is propagating through the tissue. Blue indicates a small arrival time and red indicates a large arrival time.

Table 1. Subject demographics.

Table 1. Subject demographics.

Subject DemographicsAge (years)mean (SD)62.7 (8.7)Gender (n)male/female7/3Time since stroke onset (years)mean (SD)13.4 (3.9)Stroke etiology (n)ischemic/hemorrhagic1/9ROM changes after treatment: (Group 1) no change; (Group 2) change.Group1/26/4

Table 2. Characteristics of subjects: Abbreviations: period, period since stroke onset (years); dose, BoNT-A dose (units); GCM, gastrocnemius medialis; GCL, gastrocnemius lateralis; Sol soleus; Timing, days to evaluation after BoNT-A injection; MHS, modified Heckmatt scale; MAS, the modified Ashworth Scale before and after BoNT-A injection; MTS X, quality of muscle reaction of the modified Tardieu scale before and after BoNT-A injection; MTS R1, the muscle reaction angle was recorded as fast as possible before and after BoNT-A injection; MTS R2, the muscle reaction angle was recorded as slow as possible before and after BoNT-A injection; SWV at rest, the shear wave velocity at rest before and after BoNT-A injection; SWV stretched, the shear wave velocity stretched before and after BoNT-A injection; F, Female; M, Male; R, right; L, left; H, hemorrhage; I, ischemic.

Table 2. Characteristics of subjects: Abbreviations: period, period since stroke onset (years); dose, BoNT-A dose (units); GCM, gastrocnemius medialis; GCL, gastrocnemius lateralis; Sol soleus; Timing, days to evaluation after BoNT-A injection; MHS, modified Heckmatt scale; MAS, the modified Ashworth Scale before and after BoNT-A injection; MTS X, quality of muscle reaction of the modified Tardieu scale before and after BoNT-A injection; MTS R1, the muscle reaction angle was recorded as fast as possible before and after BoNT-A injection; MTS R2, the muscle reaction angle was recorded as slow as possible before and after BoNT-A injection; SWV at rest, the shear wave velocity at rest before and after BoNT-A injection; SWV stretched, the shear wave velocity stretched before and after BoNT-A injection; F, Female; M, Male; R, right; L, left; H, hemorrhage; I, ischemic.

AgeSexStroke Hemisphere EtiologyPeriodDose
GCM/GCL/SolTimingMHSMASMTS
XMTS
R1MTS
R2SWV
at RestSWV Stretched1before56FLH12.250/30/5030422−1502.495.01after22−1502.462.822before60MRH10.430/30/6028432−30−202.286.77after32−30−202.323.013before77MLH1040/40/4029223−1002.67.6after1.52−502.95.254before72MLH16.340/40/4028322−40−352.233.63after22−35−252.163.65before66FRH21.840/40/5034333−25−202.783.86after23−20−152.412.96before62MRI11.740/0/4028232−40−352.542.93after22−30−201.772.537before50MRH12.140/30/4033322−30−252.173.56after21−30−251.642.958before71FRH17.740/0/4028333−35−301.924.14after1.51.5−1002.083.59before59MLH12.920/0/4029432−30−102.766.78after1.52−25−102.363.3810before54MRH9.450/50/7026332−45−352.643.21after32−40−352.12.52

Table 3. Changes after BoNT-A injection changes and correlations between SWV and clinical examinations. Abbreviations: IQR, interquartile range; o, degree; m/s, meters per second; MAS, the modified Ashworth Scale; MTS X, quality of muscle reaction of the modified Tardieu scale; R1, the muscle reaction angle was recorded as fast as possible; R2, the muscle reaction angle was recorded as slow as possible before BoNT-A injection; SWV at rest, the shear wave velocity at rest; SWV stretched, the shear wave velocity stretched. ap-values for continuous variables are form Wilcoxon rank sum tests. * Statistically significant (p < 0.05).

Table 3. Changes after BoNT-A injection changes and correlations between SWV and clinical examinations. Abbreviations: IQR, interquartile range; o, degree; m/s, meters per second; MAS, the modified Ashworth Scale; MTS X, quality of muscle reaction of the modified Tardieu scale; R1, the muscle reaction angle was recorded as fast as possible; R2, the muscle reaction angle was recorded as slow as possible before BoNT-A injection; SWV at rest, the shear wave velocity at rest; SWV stretched, the shear wave velocity stretched. ap-values for continuous variables are form Wilcoxon rank sum tests. * Statistically significant (p < 0.05).

Before BoNT-A InjectionAfter BoNT-A Injectionp-Value aMAS
(Median (IQR))3 (2–3)2 (1.5–3)* 0.041MTS X
(Median (IQR))2 (2–3)2 (2–2)0.102R1 (o)
(Median (IQR))−30 (−40–−22.5)−27.5 (−31.3–−13.8)* 0.014R2 (o)
(Median (IQR))−22.5 (−35.0–−7.5)−17.5 (−25.0–0.0)0.068SWV at rest (m/s)
(Median (IQR))2.52 (2.21–2.67)2.24 (2.00–2.42)0.093SWV stretched (m/s)
(Median (IQR))4.00 (3.47–6.77)2.98 (2.74–3.52)* 0.005

Table 4. Pearson’s correlations between SWV and clinical examinations. Abbreviations: r, Pear-son’s correlation coefficient; p, Bonferroni-corrected p-value (p = 0.0125); Period, period since stroke onset; R1, the muscle reaction angle was recorded as fast as possible; R2, the muscle reaction angle was recorded as slow as possible before BoNT-A injection; SWV at rest, the shear wave velocity at rest; SWV stretched, the shear wave velocity stretched. * Statistically significant, after adjustment for multiple tests using Bonferroni correction.

Table 4. Pearson’s correlations between SWV and clinical examinations. Abbreviations: r, Pear-son’s correlation coefficient; p, Bonferroni-corrected p-value (p = 0.0125); Period, period since stroke onset; R1, the muscle reaction angle was recorded as fast as possible; R2, the muscle reaction angle was recorded as slow as possible before BoNT-A injection; SWV at rest, the shear wave velocity at rest; SWV stretched, the shear wave velocity stretched. * Statistically significant, after adjustment for multiple tests using Bonferroni correction.

AgePeriodMTS R1MTS R2SWV at restr−0.106−0.0890.2270.364before BoNT-A injectionp0.770.8060.5280.301SWV at restr0.534−0.0120.6020.579after BoNT-A injectionp0.1110.9740.0660.079SWV stretchedr0.283−0.3250.663* 0.773before BoNT-A injectionp0.4280.3590.036* 0.009SWV stretchedr0.749−0.0690.6380.534after BoNT-A injectionp0.0130.850.0470.112

Table 5. Spearman Rho Correlation Results between SWV and clinical examination. Abbreviations: ρ, Spearman rho correlation coefficient; p, Bonferroni-corrected p-value (p = 0.017); Period, period since stroke onset; R1, the muscle reaction angle was recorded as fast as possible; R2, the muscle reaction angle was recorded as slow as possible before BoNT-A injection; SWV at rest, the shear wave velocity at rest; SWV stretched, the shear wave velocity stretched; MHS, modified Heckmatt scale; MAS, the modified Ashworth Scale; MTS X, quality of muscle reaction of the modified Tar-dieu scale.

Table 5. Spearman Rho Correlation Results between SWV and clinical examination. Abbreviations: ρ, Spearman rho correlation coefficient; p, Bonferroni-corrected p-value (p = 0.017); Period, period since stroke onset; R1, the muscle reaction angle was recorded as fast as possible; R2, the muscle reaction angle was recorded as slow as possible before BoNT-A injection; SWV at rest, the shear wave velocity at rest; SWV stretched, the shear wave velocity stretched; MHS, modified Heckmatt scale; MAS, the modified Ashworth Scale; MTS X, quality of muscle reaction of the modified Tar-dieu scale.

MHSMASMTS XSWV at restρ−0.0130.3550.114before BoNT-A injectionp0.9710.3140.754SWV at restρ0.243−0.230.634after BoNT-A injectionp0.4980.5220.049SWV stretchedρ0.395−0.1420.342before BoNT-A injectionp0.2590.6950.334SWV stretchedρ−0.072−0.632−0.201after BoNT-A injectionp0.8430.0510.577