Celiac artery compression by the median arcuate ligament: a pitfall of end-expiratory MR imaging.

PURPOSE

To measure the prevalence and degree of celiac artery compression during breath-hold imaging at end inspiration and end expiration in patients referred to undergo magnetic resonance (MR) imaging of the abdomen for reasons unrelated to intestinal ischemia.

MATERIALS AND METHODS

A series of 100 patients underwent routine MR imaging of the upper abdomen at 1.5 T; imaging included multiple dynamic contrast-enhanced fat-suppressed transverse three-dimensional spoiled gradient-echo acquisitions (3.6-4.5/1.5-1.9 [repetition time msec/echo time msec], 12 degrees flip angle). Arterial phase acquisitions were obtained during suspended respiration at end expiration (n = 50) or at end inspiration (n = 50), and venous phase acquisitions were obtained at the opposite respiratory phase. Two radiologists, blinded to patient identity and the phase of respiration, independently assessed the degree of narrowing on reconstructed oblique sagittal images. Radiologists reached consensus in 97 patients, who formed the cohort for this study. The percentage of stenosis of the celiac artery relative to its origin and the angle formed by the proximal celiac artery and the aorta were also measured in all patients. This angle and the arcsine transformation of the percentage of stenosis were compared for the two respiratory phases by using a paired Student t test. chi2 analysis was used to evaluate whether the degree of narrowing was independent of the breath-hold protocol that was used.

RESULTS

In total, 55 (57%) of 97 patients had at least mild artery narrowing at end expiration, of whom 40 (73%) had less narrowing at end inspiration and 11 (20%) had no change. The average percentage of stenosis at end expiration (21% +/- 16) was significantly higher than that at end inspiration (11% +/- 11; P <.001). At end expiration, the average celiac artery angle was significantly lower in patients with mild to severe narrowing (41 degrees +/- 19) than in those without narrowing (50 degrees +/- 19; P <.03).

CONCLUSION

Accentuation of celiac artery compression at end expiration can give rise to a potential pitfall of breath-hold abdominal imaging. When compression is suspected, imaging should be performed during inspiration.