Investigations on the effect of caffeine on cerebral venous vessel contrast by using susceptibility-weighted imaging (SWI) at 1.5, 3 and 7 T

Caffeine lowers the blood oxygenation level-dependent (BOLD) signal by acting as an adenosine antagonist, thus decreasing the cerebral blood flow (CBF). The aims of this study were to demonstrate the sensitivity of susceptibility-weighted imaging (SWI) to caffeine-induced changes in CBF and to investigate the time course and magnitude of signal change in caffeine-habituated and -abstinent volunteers. High-resolution susceptibility-weighted images were acquired with both groups at 1.5 T using a fully velocity compensated 3D gradient echo sequence. Following a native scan, subjects were given a tablet containing 200 mg of caffeine. Scans were repeated for about 1h and the acquired 3D data sets were coregistered to each other. BOLD signal changes of several venous vessels were analyzed in dedicated ROIs. Maps of relative signal change clearly visualized the caffeine-induced signal response of veins. Only very weak signal changes of about -2 +/- 1% were found in both, grey and white matter and -1 +/- 2% in the ventricles. Maximum signal decrease of veins occurred 40-50 min after caffeine ingestion. The signal decrease was -16.5 +/- 6.5% and -22.7 +/- 8.3% for the caffeine users group and abstainers, respectively. The signal difference of both groups was statistically significant (Student's t-test, t=2.16, p=0.021). Data acquired at 1.5, 3 and 7 T with echo times scaled to the respective field strength display very similar temporal signal behavior. (c) 2007 Elsevier Inc. All rights reserved.