Physiological effect of caffeine in neurological studies based on Susceptibility Weighted Imaging (SWI)

Abstract

Introduction – The present study investigates the effect of caffeine on the contrast-to-noise ratio (CNR) in SWI images. Purpose – Data analyses included qualitative and quantitative measures, specifically the CNR pre and post-ingestion, in magnitude and MIP images. The structures evaluated were the internal cerebral vein, superior sagital sinus, torcula, and middle cerebral artery. Methodology – Twenty-four healthy volunteers were enrolled in the study. All the volunteers were caffeine-free for 24h prior to the test. SWI images were acquired before caffeine ingestion and post-ingestion of 100 ml of coffee. The volunteers were divided into four groups of six subjects and evaluated sequentially (15, 25, 30, and 45 min after caffeine). High-resolution T2* weighted 3D GRE (SWI) sequence was acquired on the axial plane on a 1.5 T (Siemens Avanto) whole body scanner using the manufacturer’s standard head coil and the following parameters: TR=49; TE=40; FA=15; FOV=187x230; matrix=221x320. Statistics were performed with GraphPad Prismâ and image analysis with Osirixâ. Results and Discussion – We verified that signal alterations and contrast differences were predominant in venous structures and not significant in white matter, CSF, and the middle cerebral artery. The CNR values between pre and post-caffeine ingestion in magnitude and MIP images in an internal cerebral vein (p<0.0001) and in magnitude images of superior sagittal sinus and tórcula showed significant differences in CNR. There were no significant differences between groups evaluated at different times after the ingestion of caffeine. Conclusion – We speculate that caffeine can be used as a cost-effective, safe, and easy-to-administrate contrast agent on SWI images.