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The Reproducibility of the 133 Xe Inhalation Technique in Resting Studies: Task Order and Sex Related Effects in Healthy Young Adults

Repeated applications of the 133 Xe inhalation technique for measuring regional CBF (rCBF) were made during consecutive resting conditions in a sample of young healthy subjects. Subjects were grouped by order and by sex [nine had resting studies as the initial two measurements in a series of four me...

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Bibliographic Details
Published in:Journal of cerebral blood flow and metabolism 1987-12, Vol.7 (6), p.702-708
Main Authors: Warach, Steven, Gur, Ruben C., Gur, Raquel E., Skolnick, Brett E., Obrist, Walter D., Reivich, Martin
Format: Article
Language:English
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Summary:Repeated applications of the 133 Xe inhalation technique for measuring regional CBF (rCBF) were made during consecutive resting conditions in a sample of young healthy subjects. Subjects were grouped by order and by sex [nine had resting studies as the initial two measurements in a series of four measurement (six men, three women) and six had these measurements later (two men, four women)]. Three flow parameters were examined: f 1 (fast flow) and IS (initial slope) for gray matter CBF, and CBF-15 for mean CBF (gray and white matter over 15-min integration), as well as w 1 , the percentage of tissue with fast clearing characteristics. With all groups combined, there were no significant differences between the two resting measurements, and high test-retest correlations were obtained for the flow parameters and w 1 . Analyses by order and sex grouping revealed, for the flow parameters, significant interactions of test-retest difference with order. Repeated initial studies showed reduced CBF from the first to second measurement, whereas resting studies performed later in the series showed no reduction. Interactions for test-retest difference with sex indicated that reduced CBF in serial measures was more pronounced for women. No hemispheric or regional specificity to account for these effects was found. Correction for P a CO 2 differences did not alter these results. The results resemble data regarding habituation effects measured for other psychophysiologic measures, and suggest that reduction in CBF for consecutive measurements made on the same day may reflect habituation. This underscores the importance of controlling for effects of habituation on serial measurements of CBF and metabolism.
ISSN:0271-678X
1559-7016
DOI:10.1038/jcbfm.1987.124