Correlation between muscle mass and quality around the hip and of psoas muscles at L3 level using unenhanced CT scans

Objective: CT segmentation of psoas muscles at L3 level is used to measure sarcopenia status, but it is not feasible when L3 is not included in the examination. We tested the correlation of psoas muscle mass and quality estimation at L3 with that of hip muscles, which could be opportunistically used in patients undergoing hip surgery. Materials and methods: Unenhanced abdominal CT performed in 50 patients (29 males, mean/median age 69/72 years) were reviewed. Regions of interest were drawn to assess cross-sectional area (CSA) and attenuation of psoas muscles at L3. These values were correlated with CSA and attenuation of iliopsoas, rectus femoris, sartorius, and tensor fascia latae at the level of the hip, separately on each side. After applying Bonferroni correction for multiple comparisons, statistical significance was set as P <.002. Results: Attenuation of each psoas at L3 and ipsilateral hip muscles was significantly correlated (P ≤.001, r =.491–.754). A significant correlation was observed between CSA of right psoas and ipsilateral muscles (P ≤.00, r =.432–.525). We observed a significant correlation between CSA of left psoas and ipsilateral rectus femoris, iliopsoas, tensor fascia latae at the apex of the femoral head, and sartorius at the level of the lesser trochanter (P ≤.001, r =.431–.502). Average time to measure CSA and attenuation of psoas muscles at L3 was 41 s, that of hip muscles was 2 min 12 s. Conclusion: Measurements of mass and quality of hip muscles are feasible and correlate to those of psoas muscles at L3, being potentially used in future works on the association of sarcopenia and outcomes after hip surgery.