Radiographic evaluation of the psoas and iliopsoas muscle as predictors for spinal cord ischemia after fenestrated and branched endovascular aortic repair.

OBJECTIVE: This study aimed to investigate the association between sarcopenia and spinal cord ischemia (SCI) after fenestrated and branched endovascular aortic repair (F/B-EVAR) using two- and three-dimensional measurements of the psoas and iliopsoas muscles on preoperative computed tomography angiography (CTA).

METHODS: A retrospective, two-center study was conducted and reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. Data were collected from patients with Crawford type I-IV thoracoabdominal aortic aneurysms (TAAA) and pararenal abdominal aortic aneurysms treated with F/B-EVAR between December 2010 and January 2024. One center included all consecutive patients, whereas from the other center, patients with SCI were actively selected together with non-SCI patients in a 1:1 fashion based on patient and procedural characteristics. Preoperative CTAs were analyzed for surrogate markers of sarcopenia, including the psoas muscle area (cm2), lean psoas muscle area (cm2∗HU [Hounsfield units]), iliopsoas muscle volume (cm3), and lean iliopsoas muscle volume (cm3∗HU). Area measurements were performed manually, whereas volume measurements were performed using an artificial intelligence-based segmentation tool. The primary outcome was to evaluate the predictive value of the measured sarcopenia surrogate markers for SCI occurrence.

RESULTS: A total of 138 patients (35.5% female; median age 72 years, interquartile range [IQR]: 68-75 years), with 16 Crawford type I (11.6%), 45 type II (32.6%), 30 type III (21.7%), and 47 type IV/pararenal (34.1%) aneurysms, were included. Fifty-one patients had postoperative SCI (all severities), and 87 had no SCI symptoms. Compared with non-SCI patients, patients with SCI had higher American Society of Anesthesiologists classification (P = .005), more commonly type II TAAA (P < .001), and symptomatic presentation (P = .016). Other patient characteristics were similar between the groups. Psoas muscle area (6.97 cm2 [IQR: 5.22-8.73 cm2] vs 8.47 cm2 [IQR: 6.39-10.03 cm2], P = .003), lean psoas muscle area (253.3 cm2∗HU [IQR: 204.9-333.8 cm2∗HU] vs 335.6 cm2∗HU [IQR: 256.3-409.7 cm2∗HU], P = .002), iliopsoas muscle volume (247.6 cm3 [IQR: 184.0-303.8 cm3] vs 277.7 cm3 [IQR: 234.1-331.5 cm3], P = .018), and lean iliopsoas muscle volume (10,879 cm3∗HU [IQR: 8589-14,497 cm3∗HU] vs 13,445 cm3∗HU [IQR: 10,777-16,396 cm3∗HU], P = .004) were lower in patients with SCI in the unadjusted analyses. On multivariable analysis, only psoas muscle area was independently associated with SCI (odds ratio: 0.815; 95% confidence interval: 0.680-0.977, P = .027).

CONCLUSIONS: Psoas muscle area was independently associated with SCI after F/B-EVAR, indicating that patients with signs of sarcopenia on preoperative CTA may be at a higher risk for SCI. Volumetric iliopsoas muscle measurements were not better predictors of SCI than two-dimensional measurements of the psoas muscle area.