Design and Validation of a Novel Method to Measure Cross-Sectional Area of Neck Muscles Included during Routine MR Brain Volume Imaging

Abstract

IntroductionLow muscle mass secondary to disease and ageing is an important cause of excess mortality and morbidity. Many studies include a MR brain scan but no peripheral measure of muscle mass. We developed a technique to measure posterior neck muscle cross-sectional area (CSA) on volumetric MR brain scans enabling brain and muscle size to be measured simultaneously.MethodsWe performed four studies to develop and test: feasibility, inter-rater reliability, repeatability and external validity. We used T1-weighted MR brain imaging from young and older subjects, obtained on different scanners, and collected mid-thigh MR data.ResultsAfter developing the technique and demonstrating feasibility, we tested it for inter-rater reliability in 40 subjects. Intraclass correlation coefficients (ICC) between raters were 0.99 (95% confidence intervals (CI) 0.98–1.00) for the combined group (trapezius, splenius and semispinalis), 0.92 (CI 0.85–0.96) for obliquus and 0.92 (CI 0.85–0.96) for sternocleidomastoid. The first unrotated principal component explained 72.2% of total neck muscle CSA variance and correlated positively with both right (r = 0.52, p = .001) and left (r = 0.50, p = .002) grip strength. The 14 subjects in the repeatability study had had two MR brain scans on three different scanners. The ICC for between scanner variation for total neck muscle CSA was high at 0.94 (CI 0.86–0.98). The ICCs for within scanner variations were also high, with values of 0.95 (CI 0.86–0.98), 0.97 (CI 0.92–0.99) and 0.96 (CI 0.86–0.99) for the three scanners. The external validity study found a correlation coefficient for total thigh CSA and total neck CSA of 0.88.DiscussionWe present a feasible, valid and reliable method for measuring neck muscle CSA on T1-weighted MR brain scans. Larger studies are needed to validate and apply our technique with subjects differing in age, ethnicity and geographical location.

Survival prediction using temporal muscle thickness measurements on cranial magnetic resonance images in patients with newly diagnosed brain metastases

“…Kilgour et al [15] suggested the use of cross-sectional areas of neck muscles at the midpoint level of C2 to investigate the age-related loss of muscle mass on brain MR scans. However, a limitation of this technique is that these muscles are, in most cases, only incompletely depicted on routine cranial MR images.…”

Inter-rater reliability of trunk muscle morphometric analysis

“…In the cervical spine, extensor muscle CSA inter-rater reliability was also shown to be high between two assessors with an ICC of 0.84 (19), although in that study it was also not described whether these findings relate to combined muscles or individual muscle data or what the experience levels were of the assessors. Kilgour and colleagues (20) have more clearly defined inter-rater reliability between two assessors for some cervical spine muscle CSA individually (ICC of 0.92 for both obliquus capitis inferior and sternocleidomastoid muscles) and some muscles as a group (ICC 0.99 for combined trapezius, splenius and semispinalis muscles), based on T1 weighted MRI from 37 participants, although detail on assessor experience was also lacking.…”

“…As this is often lacking, the present study identifies inter-rater reliability of muscle volume and MFI for the left and right sides of several trunk muscles individually. In existing literature, frequently the inter-rater reliability of combined muscles, rather than individual muscles, has been reported (7,19,20 …”

Neck muscle cross-sectional area, brain volume and cognition in healthy older men; a cohort study

“…We have previously shown in a study of 24 subjects that neck muscle CSA is strongly correlated with thigh muscle CSA (R 2 0.77), which is often used as a proxy for general muscle bulk [46]. Neck muscle CSA is generally available in brain MRI studies, whereas thigh muscle CSA is not usually measured within longitudinal cognitive ageing studies.…”

“…Neck muscle CSA is generally available in brain MRI studies, whereas thigh muscle CSA is not usually measured within longitudinal cognitive ageing studies. Neck muscle CSA was measured using a validated technique [46]. Full details can be obtained in the technique paper; however, in summary, the mid-point of the C2-vertebra was located in the sagittal slice of a 3D reconstructed image.…”