Abstract 289: Utilization Of Intra-Arterial Contrast For Computed Tomography Aortography In A Swine Model

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Background: Intraoperative computed tomography (CT) imaging with endovascular catheter delivery of intra-arterial (IA) contrast could potentially provide higher signal attenuation in directed anatomic locations with lower contrast volumes. We compared image quality and attenuation timing of IA versus IV contrast protocols for abdominal imaging. Methods: Five anesthetized swine had internal jugular access and ascending aortic pigtails placed percutaneously via the brachial artery. The IV contrast protocol utilized 100 mL of iodinated contrast at 5 mL/sec over 20/sec. The IA protocol delivered 50 mL at 5 mL/sec over 10/sec. A 16-slice CT scanner with a 10 mm detector acquired static serial images at 1 image/second for 45 secs. Region-of-interest markers were used to select the aorta and portal vein to capture arterial and venous attenuation via Hounsfield Units (HU) per second. Attenuation curves were assessed using a Pearson’s correlation. Adequate attenuation was defined as >100 HU a priori and image quality assessed using Contrast-to-Noise Ratio (CNR). Results: Both contrast protocols achieved adequate image attenuation with an aortic peak of 665 ± 226 (Mean HU ± SD) for IA and 414 ± 141 for IV. IA contrast achieved faster peak aortic attenuation compared to IV contrast [8 vs 20 sec; p<0.001] (Fig 1). Portal values (attenuation and time to peak) were similar for IA vs IV: [146 ± 46 vs 169 ± 39; 34 vs 42 sec; p<0.05]. IA administration achieved a superior CNR in less time compared to IV [10 vs 23 sec; p<0.001]. All curves were modeled using non-linear least squares regression and achieved an R 2 >0.94; p<0.001. Conclusion: IA contrast achieves adequate opacification and a superior CNR compared to IV contrast, while using a smaller volume for intraoperative directed imaging. The incorporation of intraoperative CT with IA contrast could radically change imaging protocols for endovascular aortic repair.