Association between muscle strength and echogenicity using greyscale ultrasound software: a diagnostic accuracy study in kidney transplant candidates.
Carolina Acuña-Pardo, Elena Muñoz-Redondo, Lou Delcros-Forestier and 7 others
PMID 39679795WHAT IT FOUND
Ultrasound brightness of the thigh muscle correlated with lower leg strength in kidney transplant candidates.
A brightness score above 70 flagged weakness with fair accuracy, but the test cannot replace direct strength measurement as a standalone screening tool.
Key findings
01A greyscale echogenicity cut-off of 70 showed fair validity for identifying muscle weakness, with 59.7% sensitivity and 57.5% specificity.
02Patients with echogenicity above 70 had a 3.4-fold increased risk of muscle weakness, and this association persisted after adjusting for age, sex, and muscle thickness.
03The authors conclude that while ultrasound brightness correlates with strength, it cannot be recommended as a standalone screening tool for muscle weakness.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study only included patients referred to a prehabilitation program, so results may not apply to all kidney transplant candidates. The sample was predominantly male (76.8%), limiting generalizability to women. Ultrasound measurements can vary based on probe positioning and settings, which may affect reliability in different clinical settings. The test had fair validity only, meaning it misses a significant number of people with weakness (false negatives) and flags people who are not weak (false positives).
Declared interests
The authors declared no conflicts of interest. The study was funded by the Spanish Society of Transplantation and the FRAILMAR project (FIS-FEDER PI19/00037).
The easy way to misread this
Do not use ultrasound echogenicity as a replacement for direct strength testing. The test has only fair validity (59.7% sensitivity), meaning it will miss many patients with muscle weakness. A normal ultrasound does not rule out weakness.