Identifying Anatomical Predictors of Median Arcuate Ligament Overlap to Guide Selective Use of Contrast-Enhanced Computed Tomography in Adult Spinal Deformity Surgery

Abstract

Introduction: Acute celiac artery compression syndrome (ACACS) is a rare but potentially life-threatening complication following surgery for adult spinal deformity (ASD); it is caused by compression of the celiac artery (CA) by the median arcuate ligament (MAL). MAL overlap, the condition in which the MAL overlaps the base of the CA, has been identified as a potential risk factor for ACACS after ASD surgery. However, the routine use of contrast-enhanced computed tomography (CT) to assess this condition poses risks such as allergy and renal dysfunction. The aim of this study was to identify anatomical predictors of MAL overlap using non-contrast imaging markers.

Methods: We retrospectively reviewed the data of 43 patients who underwent contrast-enhanced abdominal CT and non-contrast thoracolumbar CT as part of their preoperative evaluation. MAL overlap and MAL levels were assessed using reconstructed contrast-enhanced abdominal CT images; non-contrast thoracolumbar CT was reviewed for comparison. To determine the risk factors for MAL overlap, patients were divided into two groups based on their MAL overlap. The patient characteristics, spinopelvic parameters obtained from radiographs, and MAL levels of the two groups were compared. Diagnostic agreement between contrast-enhanced and non-contrast CT was evaluated using kappa statistics.

Results: MAL overlap was observed in 15 of 43 patients (34.8%); it was significantly associated with MAL levels below T12 (p=0.004). The agreement between contrast-enhanced and non-contrast CT assessments was perfect for MAL level (κ=1.000).

Conclusions: The prevalence of MAL overlap was 34.8% in patients with ASD preoperatively. MAL levels below the T12 vertebra are risk factors for MAL overlap. Importantly, the MAL level could be accurately evaluated using plain CT. This is useful to clinicians for the selection of patients with ASD who require further examination using contrast agents to evaluate preoperative CA stenosis or MAL overlap.