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 STROBE guidelines. Data was collected from patients with Crawford type I-IV thoracoabdominal aortic aneurysms (TAAA) and pararenal abdominal aortic aneurysms (AAA) treated with F/B-EVAR between December 2010 and January 2024. One center included all consecutive patients, while from the other center, SCI patients 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 (LPMA, [cm2*HU]), iliopsoas muscle volume [cm3], and lean iliopsoas muscle volume (LIMV, [cm3*HU]). Area measurements were performed manually, while 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, 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 to non-SCI patients, SCI patients had higher ASA classification (p=0.005), more commonly type II TAAA (p<0.001), and symptomatic presentation (p=0.016). Other patient characteristics were similar between the groups. Psoas muscle area (6.97 cm2 [IQR: 5.22-8.73] vs. 8.47 cm2 [IQR: 6.39-10.03], p = 0.003), LPMA (253.3 cm2*HU [IQR: 204.9-333.8] vs. 335.6 cm2*HU [IQR: 256.3-409.7], p = 0.002), iliopsoas muscle volume (247.6 cm3 [IQR: 184.0 - 303.8] vs. 277.7 cm3 [IQR: 234.1 - 331.5], p = 0.018), and LIMV (10879 cm3*HU [IQR: 8589 - 14497] vs. 13445 cm3*HU [IQR: 10777 - 16396], p = 0.004) were lower in SCI patients in the unadjusted analyses. On multivariable analysis, only psoas muscle area was independently associated with SCI (OR: 0.815; 95% CI: 0.680-0.977, p=0.027). CONCLUSION: 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 higher risk for SCI. Volumetric iliopsoas muscle measurements were not better predictors of SCI than two-dimensional measurements of the psoas muscle area.