Can Sublingual Nitrate Improve Visualization of Lower Limb Arteries on Computed Tomography Angiography?

OBJECTIVE: The aim of the study is to evaluate the role of sublingual nitrate in improving vessel visualization on peripheral computed tomography angiography (CTA). METHODS: Fifty patients clinically diagnosed with peripheral arterial disease of the lower limb were prospectively included in this study: Twenty-five underwent CTA after sublingual nitrate administration (nitrate group) and 25 without (non-nitrate group). Two blinded observers qualitatively and quantitatively assessed the data thus generated. The mean luminal diameter, intraluminal attenuation, site, and percentage of stenosis were evaluated in all segments. Assessment of collateral visualization at sites of significant stenosis was also done. RESULTS: Patients in the nitrate and non-nitrate groups were similar in age and sex characteristics ( P > 0.05).On subjective evaluation, there was significantly improved visualization of the femoropopliteal and tibioperoneal vasculature of the lower limb in the nitrate group compared with the non-nitrate group ( P < 0.05). Quantitative evaluation showed a statistically significant difference in the measured arterial diameters for all evaluated segments in the nitrate group versus the non-nitrate group ( P < 0.05). Intra-arterial attenuation was significantly greater for all segments in the nitrate group resulting in better contrast opacification in these studies. Collateral visualization around segments with more than 50% stenosis/occlusion was also better in the nitrate group. CONCLUSIONS: Our study suggests that nitrate administration before peripheral vascular CTA can improve visualization, especially in the distal segments by increasing the vessel diameter and intraluminal attenuation along with better delineation of the collateral circulation around stenotic areas. It may also improve the number of evaluable segments of vasculature in these angiographic studies.