Abstract

Tracer studies have demonstrated that 100% oxygen inhalation causes a small cerebral blood flow (CBF) decrease. This study was performed to determine whether arterial spin-labeling (ASL), a noninvasive MR imaging technique, could image these changes with clinically reasonable imaging durations.Continuous ASL imaging was performed in 7 healthy subjects before, during, and after 100% oxygen inhalation. ASL difference signal intensity (DeltaM, control - label), CBF, and CBF percentage change were measured. A test-retest paradigm was used to calculate the variability of the initial and final room air CBF measurements.During oxygen inhalation, DeltaM decreased significantly in all regions (eg, global DeltaM decreased by 23 +/- 11%, P < .01, all values mean +/- SD). Accounting for the reduced T1 of hyperoxygenated blood, we found a smaller CBF decrease, which did not reach significance in any of the regions. Global CBF dropped from 50 +/- 10 mL per 100 g/minute to 47 +/- 10 mL per 100 g/minute following 100% oxygen inhalation, a decrease of 5 +/- 14% (P > .17). The root-mean-square variability of the initial and final room air CBF measurements was 7-8 mL per 100 g/minute.The DeltaM signal intensity decreased significantly with oxygen inhalation; however, after accounting for changes in blood T1 with oxygen, CBF decreases were small. Such measurements support the use of hyperoxia as an MR imaging contrast agent and may be helpful to interpret hyperoxia-based stroke trials.

View details for DOI 10.3174/ajnr.A0896

View details for Web of Science ID 000255129700009

View details for PubMedID 18397966