Criterion Validity of Ultrasound Imaging: Assessment of Multifidi Cross-Sectional Area in Older Adults With and Without Chronic Low Back Pain.
Jaclyn Megan Sions, Deydre S Teyhen, Gregory E Hicks
PMID 26703525WHAT IT FOUND
Averaging 3 ultrasound images agreed with MRI for L4 multifidi cross-sectional area in older adults with and without chronic low back pain.
A single image was less reliable in pain-free older adults. Ultrasound may include fat.
Key findings
01The average of 3 ultrasound images agreed with MRI better than a single image and showed no significant CSA differences in either group.
02A single ultrasound image had lower agreement with MRI in older adults without CLBP than in older adults with CLBP, although its CSA measurements were not significantly different from MRI.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 20 older adults were studied, with 10 in each group. The study tested only the L4 level, so it does not show whether ultrasound is valid at adjacent spinal levels. The examiner was experienced with ultrasound and MRI processing, so results may not apply to novice examiners. Examiners were not blinded to whether participants had low back pain. Ultrasound and MRI were not performed at the same time; MRI occurred within 10 days after ultrasound. Ultrasound may include intramuscular fat and muscle, so measured cross-sectional area may overstate functional muscle size. The study did not assess erector spinae muscles because of ultrasound screen limitations. The same examiner performed ultrasound, processed images, and made MRI measurements.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that ultrasound measures functional multifidi muscle size. The study showed agreement with MRI for cross-sectional area, but ultrasound cannot separate intramuscular fat from surrounding tissue, so the measured area may include fat and overstate functional muscle.