Investigation of human skeletal muscle structure and composition by X-ray computerised tomography.

In muscular dystrophy and metabolic myopathy there is wasting and replacement of the muscle bulk with fat and fibrous tissue. A method for estimating the fat content of muscle and the cross-sectional area from computerised tomography (CT) scans is presented. Data from the quadriceps muscle of fifty patients show the effect of fat replacement on muscle strength. The CT scans have shown that the pattern of wasting in individual muscle groups is characteristic of the type of myopathy. In Duchenne muscular dystrophy, hypertrophic and pseudohypertrophic muscle have hitherto been indistinguishable, but this method allows a clear distinction to be made. Quantitative CT offers a new approach to the investigation of muscle diseases and can also be of considerable value in selecting sites for needle biopsy of muscle.