Is Posterior Neck Muscle Cross Sectional Area as Seen on MRI Brain Scans, a Good Indicator of General Sarcopenia?

Purpose: Sarcopenia, loss of muscle bulk often associated with frailty, is reliably measured by MR determination of cross-sectional areas (CSA) of large skeletal muscles. Craniad neck muscles are imaged as part of routine MRI brain volume acquisitions. We sought to establish a reliable method for measuring neck muscles CSAs from routine brain MRIs.

Material and Methods: Volumetric T1-weighted images were acquired at 1.5 Tesla (isotropic 1.3mm voxels). CSAs of 1) trapezius, splenius capitis, semispinalis capitis as a group, 2) obliquus capitis inferior and 3) sternocleidomastoid (SCM) were measured bilaterally in the mid-C2 transverse plane of 40 community-resident volunteers aged 72 years, independently by two raters on three occasions.

Results: 37 scans were of adequate quality to allow measurement. Mean difference between raters was 0.3% (95% CI -1.5, 2.0%) of mean CSA. CSA intraclass correlation coefficients between raters were: 0.99 (95% confidence intervals 0.98-0.995) for trapezius, splenius and semispinalis combined; 0.92 (95% C.I. 0.85-0.96) for obliquus; and 0.92 (95% C.I. 0.85-0.96) for sternocleidomastoid. CSAs all correlated highly significantly with each other (p<.001).

Conclusion: Reliable measurement of craniad neck muscle CSA is feasible from routine MRI brain volume acquisitions. The method will facilitate investigation of relationships between sarcopenia and brain aging.