Influences of clinical experience in the quantification of morphometric sarcopaenia: a cohort study.

Objective: The measurement of total psoas muscle area (TPMA) on CT imaging is commonly made using either manual tracing or a semi-automated technique. We examined whether clinical experience influenced measurement of TPMA when utilising these two commonly used methods and describe the relationship between techniques. Methods: Pre-operative cross-sectional CT imaging of 114 consecutive patients undergoing elective endovascular aneurysm repair were analysed. Retrospective measurements of the TPMA were performed by four independent investigators with a range of clinical experience (medical student to specialist surgical registrar) using either technique. Intra- and inter-observer differences were assessed. Results: There was no significant intra- or inter-observer differences when measuring the TPMA. Clinical experience also did not influence TPMA measurements recorded. Significant differences were observed between techniques when measuring TPMA (mean -65.8, 239.3 SD, p = 0.004). Measurement differences between techniques were highly correlated and modelled using linear regression. Conclusion: Both manual tracing and semi-automated technique quantification methods of measuring TPMA are highly reproducible and independent of assessor bias and clinical experience. Advances in knowledge: Either of the commonly used techniques to measure TPMA may be reliably used by an individual with appropriate training. We describe a relationship to facilitate comparison between these methods by which sarcopaenia may be quantified in patients with routine CT imaging.