Minimal training is required to reliably perform quantitative ultrasound of muscle.
BACKGROUND
Quantitative ultrasound can measure skeletal muscle pathology. We investigated whether inexperienced evaluators could accurately obtain and analyze ultrasound images.


METHODS
Two examiners underwent a 20-minute training session before obtaining ultrasound images of several limb muscles in 21 healthy boys and 19 boys with Duchenne muscular dystrophy (DMD). Gray scale levels (GSLs) of muscle and subcutaneous fat were then measured by 2 analysts: a trained research assistant and a radiologist. We compared results between examiners and analysts.


RESULTS
Interrater reliability of muscle GSLs was high between examiners (ICC ≥ 0.85) and analysts (ICC ≥ 0.84). As anticipated, GSLs were higher in dystrophic than in healthy muscles (P < 0.001). Fat GSLs were less reliable (ICC = 0.5-0.89) than muscle and increased with age and body size.


CONCLUSIONS
GSLs from ultrasound images of healthy and dystrophic skeletal muscle, but not from subcutaneous fat, can be obtained reliably and can be analyzed by inexperienced evaluators with minimal training.
Departments of Neurology and Pediatrics, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri, 63110, USA.
Craig M
CM
Zaidman
Jim S
JS
Wu
Sarah
S
Wilder
Basil T
BT
Darras
Seward B
SB
Rutkove
D000293:Adolescent; D000375:Aging / Q000502:physiology; D001132:Arm / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009132:Muscles / Q000000981:diagnostic imaging*; D020388:Muscular Dystrophy, Duchenne / Q000000981:diagnostic imaging; D015588:Observer Variation; D015203:Reproducibility of Results; D050151:Subcutaneous Fat / Q000000981:diagnostic imaging; D014463:Ultrasonography
Duchenne muscular dystrophy; children; muscle; myopathy; quantitative ultrasound