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Session: Poster session II
Session starts: Thursday 24 January, 16:00

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Marloes Sjoerdsma (Eindhoven University of Technology)
Maarten Heres (Eindhoven University of Technology)
Thijs Schoots (Maxima medical centre Veldhoven)
Frans van de Vosse (Eindhoven University of Technology)
Richard Lopata (Eindhoven University of Technology)

Abstract:
Continuous, dynamic ultrasonic evaluation of architectural and mechanical parameters of skeletal muscles is challenging. Additionally, intra-exercise measurements are generally more relevant compared to post-exercise parameters. Field-Of-View (FOV) consistency is often essential for measurement accuracy. However, probe orientation and position are challenging to reproduce and preserve. Probe fixation might improve FOV stability and enable continuous acquisitions during exercise. In this study, the feasibility of hands-free ultrasound was investigated in two distinctively challenging fields, i.e. myosonography and echocardiography. The FOV stability obtained by a fixated probe was compared to trained sonographers. In myosonography, longitudinal images of the vastus lateralis muscle were acquired in ten healthy volunteers whilst cycling. In echocardiography, eight exercise stress tests were performed. For both, a MyLab 70 Esaote system was employed. To overcome inter-observer variability and bias, feature-based algorithms were implemented to automatically detect and measure muscle diameter and pennation, and interventricular septum curvature and tilt. The FOV stability was assessed based on the temporal deviation in these function-related parameters and the structural similarity, measured using the Complex-Wavelet Structural Similarity Index Method (CW-SSIM). In myosonography, the CW-SSIM indices of the muscle tissue of the hands-free acquisitions were significantly superior compared to two trained sonographers (0.72 vs 0.59 and 0.67). The hands-free obtained muscle pennation and diameters were at least as consistent as the manual acquisitions. In echocardiography, the hands-free CW-SSIM indices were at least equal to the manual measurements (apical: 0.78 vs 0.66, and parasternal: 0.64 vs 0.63). However, the parasternal CW-SSIM variation of the observer was lower in comparison to the hands-free acquisitions, due to manual corrections made for respiration induced cardiac dislocation. In the future, these dislocations could be tracked and corrected automatically using a software steerable component implemented into the probe fixation device. The variation in septum curvature and tilt appeared smaller in the hands-free data (0.25 vs 0.61 mm-1 and 0.28 vs 0.58º, respectively). Hands-free, continuous, dynamic acquisitions promise to be beneficial in many clinical fields and sports. Moreover, it has the potential to decrease work-related musculoskeletal afflictions in sonographers.