In vivo muscle morphology comparison in post-stroke survivors using ultrasonography and diffusion tensor imaging

Abstract

Skeletal muscle architecture significantly influences the performance capacity of a muscle. A DTI-based method has been recently considered as a new reference standard to validate measurement of muscle structure in vivo . This study sought to quantify muscle architecture parameters such as fascicle length (FL), pennation angle (PA) and muscle thickness (t m ) in post-stroke patients using diffusion tensor imaging (DTI) and to quantitatively compare the differences with 2D ultrasonography (US) and DTI. Muscle fascicles were reconstructed to examine the anatomy of the medial gastrocnemius, posterior soleus and tibialis anterior in seven stroke survivors using US- and DTI-based techniques, respectively. By aligning the US and DTI coordinate system, DTI reconstructed muscle fascicles at the same scanning plane of the US data can be identified. The architecture parameters estimated based on two imaging modalities were further compared. Significant differences were observed for PA and t m between two methods. Although mean FL was not significantly different, there were considerable intra-individual differences in FL and PA. On the individual level, parameters measured by US agreed poorly with those from DTI in both deep and superficial muscles. The significant differences in muscle parameters we observed suggested that the DTI-based method seems to be a better method to quantify muscle architecture parameters which can provide important information for treatment planning and to personalize a computational muscle model.

Three‐dimensional architecture of human medial gastrocnemius fascicles in vivo: Regional variation and its dependence on muscle size

“…The fascicles, whose extrapolation length was longer than 30% of the original length, were excluded from further analyses (Bolsterlee et al, 2019) (Figure 2). The 2D pennation angle was computed by subtracting the angle between the fascicle vector (vector connecting both ends of fascicle) and the average normal vector of all the triangles on the MG surface mesh located within a radius of 5.0 mm around the distal end from 90° (Figure 3a), similar to previous studies (Bolsterlee et al, 2019;Körting et al, 2019). It should be noted that this angle is a simulated pennation angle measured in the ultrasonography.…”

“…The mean values of fascicle length and 2D pennation angle of the selected DTI fascicles were used for comparison with the 3DUS measurements. This approach was conceptually similar to that used in previous studies (Bolsterlee et al, 2015;Körting et al, 2019) and allowed us to compare the architecture of fascicles located at, or close to, the same region. For the regional architecture analysis of DTI-measured fascicles (right MG), the principal component analysis was performed on all of the vertices of the triangular surface mesh of MG (Bolsterlee et al, 2017;Raiteri et al, 2016).…”

“…The mean values of fascicle length and 2D pennation angle of the selected DTI fascicles were used for comparison with the 3DUS measurements. This approach was conceptually similar to that used in previous studies (Bolsterlee et al, 2015; Körting et al, 2019) and allowed us to compare the architecture of fascicles located at, or close to, the same region.…”

Passive Mechanical Properties of Human Medial Gastrocnemius and Soleus Musculotendinous Unit

“…The CSAs of the SOL, GM, and GL were estimated based on the magnetic resonance images collected earlier for the subjects using a 3T MRI scanner (Siemens Trio, Siemens Medical Solution, Erlangen, Germany) while lying in a supine position with the identical joint configuration. The detail settings for T1-weighted images were described in our previous study [ 23 ], and the CSAs were identified at the maximal circumference of the lower limb. where i = SOL, GM, and GL, F T is the tendon force, T ankle is the measured ankle torque, ma T is the moment arm, and AR is the ratio of the muscle cross-section area (CSA, Supplementary S2 ).…”

Sensitivity analyses of probabilistic and deterministic DTI tractography methodologies for studying arm muscle architecture

“…Compared with conventional methods, such as ultrasound and cadaveric dissection, DTI tractography is able to noninvasively capture a high number of muscle fascicles in superficial as well as deep skeletal muscles. [1][2][3] Most studies have implemented DTI tractography to characterize leg muscle properties [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] except for a few in the arm. 21,22 These previous studies estimated fascicle properties using deterministic algorithms to compute a binary decision for fiber tracking in contiguous voxels.…”