UltraTrack: Software for semi-automated tracking of muscle fascicles in sequences of B-mode ultrasound images

• We have developed a freely available software package for semi-automated tracking of muscle fascicles in B-mode ultrasound image sequences.
• Includes features to track multiple fascicles in multiple regions of the image and to correct for measurement drift with time.
• The software is available for Windows and MacOS as a standalone program or source code.

BackgroundDynamic measurements of human muscle fascicle length from sequences of B-mode ultrasound images have become increasingly prevalent in biomedical research. Manual digitisation of these images is time consuming and algorithms for automating the process have been developed. Here we present a freely available software implementation of a previously validated algorithm for semi-automated tracking of muscle fascicle length in dynamic ultrasound image recordings, “UltraTrack”.MethodsUltraTrack implements an affine extension to an optic flow algorithm to track movement of the muscle fascicle end-points throughout dynamically recorded sequences of images. The underlying algorithm has been previously described and its reliability tested, but here we present the software implementation with features for: tracking multiple fascicles in multiple muscles simultaneously; correcting temporal drift in measurements; manually adjusting tracking results; saving and re-loading of tracking results and loading a range of file formats.ResultsTwo example runs of the software are presented detailing the tracking of fascicles from several lower limb muscles during a squatting and walking activity.ConclusionWe have presented a software implementation of a validated fascicle-tracking algorithm and made the source code and standalone versions freely available for download.