Computerized Tomography derived psoas muscle indices in a healthy young population in the United States

Psoas muscle metrics from diagnostic computerized tomography (CT) scans are emerging as clinically relevant biomarkers. Most muscle metrics from the US population are from older cohorts with co-morbidities. Published reports from a young or healthy population in the United States on psoas muscle metrics optimized for age, body mass index (BMI), and sex are lacking. This study determines the psoas muscle index (PMI) and psoas muscle density (PMD) for a normal young Midwestern US population.

Retrospective cross-sectional analysis of pre-existent abdominal non-contrast CT scans from a young (19-40 years old), Midwestern, predominately Caucasian population was conducted within Aquarius iNtuition software automatically after manual identification of the psoas muscle. Electronic medical records provided access to subject data and archived CT scans were reviewed.

From 193 (45 male, 148 female) CT scans, for males, PMI was 5.9 cm²/m² (SD=1.7) and PMD 48.4 HU (SD=5.5); for females PMI was 5.4 cm²/m² (SD=1.4) and PMD 48.18 HU (SD=5.5). BMI was significantly correlated with PMI and PMD for both men (p<0.001, p<0.001 respectively) and women (p<0.001, p<0.001 respectively).

Psoas muscle metrics are newly generated for PMI and PMD in a healthy population, allowing for future comparison studies determining muscle status.