NeurophysiologyRelationship between cerebral blood flow changes during visual stimulation and baseline flow levels investigated with functional MRIKastrup, Andreas1,2; Li, Tie-Qiang1; Krüger, Gunnar1; Glover, Gary H.1; Moseley, Michael E.1Author Information 1Stanford University, Department of Radiology, Lucas MRS Center, 1201 Welch Road, Stanford, CA 94305-5488, USA 2Corresponding Author: Andreas Kastrup ACKNOWLEDGEMENTS: This study was supported by research grants from the Deutsche Forschungsgemeinschaft (Ka 1419/1-1). T-Q.L. was supported by NIH NCRR P-41 09784. We thank the volunteers for their participation in the study. We are greatly indebted to H.E. D'Arceuil for reviewing the manuscript. Received 23 March 1999; accepted 13 April 1999 NeuroReport: June 3rd, 1999 - Volume 10 - Issue 8 - p 1751-1756 Buy Abstract USING fMRI, the relationship between regional cerebral blood flow (rCBF) changes during visual stimulation and the prevailing baseline global and regional flow levels was evaluated in 22 volunteers. The absolute increase in rCBF was not correlated with baseline rCBF values (r = 0.01, p = 0.8); however, the percentage change in rCBF showed a negative correlation (r = −0.78, p < 0.001). Both absolute and relative changes in rCBF were independent of baseline global CBF values. These results indicate that caution should be exercised when comparing relative flow changes during focal brain activation, especially in functional neuroimaging studies dealing with altered baseline flow values. © 1999 Lippincott Williams & Wilkins, Inc.