Validity and reliability of velocity measurements on ultrasonography using custom software with an optical-flow algorithm.
Tomoko Yamashita, Kohei Ozawa, Kazuyoshi Gamada
PMID 32158076WHAT IT FOUND
Echolizer measured pulled pork muscle movement accurately after correction, but only when muscle fibers were clear, the chosen area was not too large, and image brightness and contrast stayed near original.
Key findings
01After regression correction, the relative error was 0.2% between 2.5 and 16.5 mm/s.
02The smallest error was with a 225 mm2 region (0.51%), and the largest was with a 900 mm2 region (33.0%).
03Velocity error remained within 5% when brightness was -30 or above and contrast was between -30 and 80.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study measured pork meat, not living human muscle, so it does not prove the method works in patients. Accuracy dropped when muscle bundles were unclear, when regions were in deeper tissue, or when regions were too large. The test only checked movement parallel to the ultrasound probe, not other directions. No clinical outcomes, patients, or treatment effects were measured.
Declared interests
The Echolizer software was temporarily licensed by GLAB Co., Ltd., its vendor.
The easy way to misread this
Do not conclude that Echolizer can reliably measure muscle gliding in patients. The study used pork meat, not living human tissue, and it tested only movement parallel to the probe, so no clinical measurement was validated.