Median arcuate ligament syndrome (MALS), or celiac artery compression syndrome, is a rare clinical condition classically manifesting as vague gastrointestinal symptoms. It is caused by compression of the celiac artery or nerve plexus via the fibrous band of the diaphragm, the median arcuate ligament (MAL). However, a large subset of patients with incidental radiologic findings of celiac compression are asymptomatic and incorrectly diagnosed with MALS. On CTA, the "hook" or "J" sign, whereby the celiac artery is deviated upwards by the MAL, are suggested as diagnostic of MALS; however no literature quantifies the relationship of the hook sign to MALS.

An IRB-approved retrospective chart review (2000-2021) of all patients at a large tertiary academic center diagnosed with celiac artery compression syndrome via ICD-9/10 code was performed. Patients were assessed if correctly diagnosed with true MALS via the presence of clinical symptoms, imaging findings and exclusion of other diagnoses. The fold angle (FA; upward deflection of the celiac artery from the aorta to its initial branch) were measured from lateral aorta images on CTA (Fig1). The presence of a hook sign and >50% celiac artery stenosis was recorded. Results are mean±SD. Fisher exact and Wilcoxon rank sum test were used and *p<0.05 was considered significant.

293 patients with celiac artery compression were identified. 59.7% were female and average age was 63.9 ± 20.2 years. Only 69 (23.5%) patients had true MALS (Table 1). Their average age was 56.5 ± 20.1 years, 60.8% were female, average BMI was 26.9 ± 6.8. Their measured FA was much narrower, 120.7 ± 32.0 degrees, compared to 145 previously reported in literature(ref 1). BMI did not strongly correlate with FA angles (R2=0.04). A hook sign was identified in 57.4% of imaging. Only 74% of patients had a significant celiac artery stenosis. Of the 34 patients with a hook sign, 24 (70%) had significant stenosis. However, of the 25 patients without a hook sign, 16 (64%) also had a significant stenosis.

A hook sign or a celiac artery stenosis > 50% has poor correlation with MALS diagnosis and may represent a normal variant. This supports the hypothesis that hemodynamic compromise of the celiac artery may only play a minor role in abdominal symptoms of MALS. MALS is a syndrome that requires symptomatic correlation. A high index of suspicion combined with appropriate recognition of patient characteristics are needed to increase the accuracy of diagnosis of MALS.

[1] Petnys A, Puech-Leão P, Zerati AE, et al. Prevalence of signs of celiac axis compression by the median arcuate ligament on computed tomography angiography in asymptomatic patients. J Vasc Surg. 2018;68(6):1782-1787. doi:10.1016/j.jvs.2018.04.044