Hypercapnia has been utilized as a stimulus to elicit changes in cerebral blood flow (CBF). However, in many instances it has been delivered in a non-controlled method that is often difficult to reproduce. The purpose of this study was to examine the within- and between-visit reproducibility of blood oxygen level-dependent (BOLD) signal changes to an iso-oxic square wave alteration in end-tidal carbon dioxide partial pressure (PetCO2). Two 3-Tesla (3T) MRI scans were performed on the same visit, with two square wave alterations administered per scan. The protocol was repeated on a separate visit with minimum of 3 days between scanning sessions. PetCO2 was altered to stimulate changes in cerebral vascular reactivity (CVR), while PetO2 was held constant. Eleven subjects (six females; mean age 26·5 ± 5·7 years) completed the full testing protocol. Excellent within-visit square wave reproducibility (ICC > 0·75) was observed. Similarly, square waves were reproducible between scanning sessions (ICC > 0·7). This study demonstrates BOLD signal changes in response to alterations in PetCO2 are reproducible both within- and between-visit MRI scans.
Bibliographical noteFunding Information:
We thank Joseph Fisher MD for technical collaboration. Grants: This study was partially funded by an Equipment grant from the University of Minnesota Medical Foundation and a University of Minnesota Grant-in-Aid (D.R.D.)
- cerebral vascular reactivity
- magnetic resonance imaging
- vascular function