Quantification of skeletal muscle density, mass and fat fraction using single-energy computed tomography.

Background: Currently, CT muscle density is measured in Hounsfield units and is not converted to g/cm Methods: We propose a phantomless calibration method to calculate muscle tissue and muscle density in g/cm Results: The mean SMT CT value of the phantom measurements was 47.7 ± 1.9 HU. In line with previous publications, the SMT fat fraction was set to 3%, and the subcutaneous adipose tissue (SAT) FF to 85%. Using an SMT CT value of 48 HU, the mean muscle tissue density, muscle density, and muscle fat fraction (FF) of the 41 subjects were 0.94 ± 0.08 g/cm Conclusions: The proposed methodology for muscle calibration in single-energy CT images showed a high degree of agreement with MR Dixon FF measurements. The simulated accuracy errors were comparable to those caused by missing water offset corrections of the measured CT values. This is a proof-of-concept study, further validation in subjects with higher muscle FF and in other muscle groups is required. The translational potential of this article: Quantitative assessments of muscle properties such as density and fat infiltration are important biomarkers for myopathies, sarcopenia, obesity and potentially for osteoporosis. While MRI techniques are state-of-the-art, the opportunistic use of existing CT scans can support screening strategies and may help to identify more subjects at early risk for muscle and perhaps even bone loss. New CT technology, such as photon counting CT, which reduces radiation exposure by around 50% compared to standard CT, may also make CT attractive for dedicated muscle imaging.