Advanced

AJNR - American Journal of Neuroradiology

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Google Scholar Articles by Zaharchuk, G. Articles by Dillon, W.P. PubMed PubMed Citation Articles by Zaharchuk, G. Articles by Dillon, W.P.

American Journal of Neuroradiology 29:663-667, April 2008
© 2008 American Society of Neuroradiology

BRAIN

Noninvasive Imaging of Quantitative Cerebral Blood Flow Changes during 100% Oxygen Inhalation Using Arterial Spin-Labeling MR Imaging

G. Zaharchuk^a, A.J. Martin^b and W.P. Dillon^b

^a Department of Radiology, Stanford University, Stanford, Calif
^b Department of Radiology, University of California San Francisco, San Francisco, Calif

Please address correspondence to Greg Zaharchuk, MD, Phd, Department of Radiology, Stanford University, Mailcode 5487, 1201 Welch Rd, PS-04, Stanford, CA 94305-5487; e-mail: gregz{at}stanford.edu

BACKGROUND AND PURPOSE: 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.

Materials and METHODS: Continuous ASL imaging was performed in 7 healthy subjects before, during, and after 100% oxygen inhalation. ASL difference signal intensity (M, 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.

RESULTS: During oxygen inhalation, M decreased significantly in all regions (eg, global M 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.

CONCLUSIONS: The M 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.