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In vivo quantification of cerebral R2*-response to graded hyperoxia at 3 Tesla


Gotzamanis, G; Kocian, R; Özbay, P S; Redle, M; Eberhardt, C; Boss, A; Nanz, D; Rossi, C; Kollias, Spyridon (2015). In vivo quantification of cerebral R2*-response to graded hyperoxia at 3 Tesla. Journal of Clinical Imaging Science, 5(1):online.

Abstract

Objectives: This study aims to quantify the response of the transverse relaxation rate of the magnetic resonance (MR) signal of the cerebral tissue in healthy volunteers to the administration of air with step-wise increasing percentage of oxygen. Materials and Methods: The transverse relaxation rate (R2*) of the MR signal was quantified in seven volunteers under respiratory intake of normobaric gas mixtures containing 21, 50, 75, and 100% oxygen, respectively. End-tidal breath composition, arterial blood saturation (SaO 2 ), and heart pulse rate were monitored during the challenge. R2* maps were computed from multi-echo, gradient-echo magnetic resonance imaging (MRI) data, acquired at 3.0T. The average values in the segmented white matter (WM) and gray matter (GM) were tested by the analysis of variance (ANOVA), with Bonferroni post-hoc correction. The GM R2*-reactivity to hyperoxia was modeled using the Hill's equation. Results: Graded hyperoxia resulted in a progressive and significant (P < 0.05) decrease of the R2* in GM. Under normoxia the GM-R2* was 17.2 ± 1.1 s -1 . At 75% O 2 supply, the R2* had reached a saturation level, with 16.4 ± 0.7 s -1 (P = 0.02), without a significant further decrease for 100% O 2 . The R2*-response of GM correlated positively with CO 2 partial pressure (R = 0.69 ± 0.19) and negatively with SaO 2 (R = -0.74 ± 0.17). The WM showed a similar progressive, but non-significant, decrease in the relaxation rates, with an increase in oxygen intake (P = 0.055). The Hill's model predicted a maximum R2* response of the GM, of 3.5%, with half the maximum at 68% oxygen concentration. Conclusions: The GM-R2* responds to hyperoxia in a concentration-dependent manner, suggesting that monitoring and modeling of the R2*-response may provide new oxygenation biomarkers for tumor therapy or assessment of cerebrovascular reactivity in patients.

Abstract

Objectives: This study aims to quantify the response of the transverse relaxation rate of the magnetic resonance (MR) signal of the cerebral tissue in healthy volunteers to the administration of air with step-wise increasing percentage of oxygen. Materials and Methods: The transverse relaxation rate (R2*) of the MR signal was quantified in seven volunteers under respiratory intake of normobaric gas mixtures containing 21, 50, 75, and 100% oxygen, respectively. End-tidal breath composition, arterial blood saturation (SaO 2 ), and heart pulse rate were monitored during the challenge. R2* maps were computed from multi-echo, gradient-echo magnetic resonance imaging (MRI) data, acquired at 3.0T. The average values in the segmented white matter (WM) and gray matter (GM) were tested by the analysis of variance (ANOVA), with Bonferroni post-hoc correction. The GM R2*-reactivity to hyperoxia was modeled using the Hill's equation. Results: Graded hyperoxia resulted in a progressive and significant (P < 0.05) decrease of the R2* in GM. Under normoxia the GM-R2* was 17.2 ± 1.1 s -1 . At 75% O 2 supply, the R2* had reached a saturation level, with 16.4 ± 0.7 s -1 (P = 0.02), without a significant further decrease for 100% O 2 . The R2*-response of GM correlated positively with CO 2 partial pressure (R = 0.69 ± 0.19) and negatively with SaO 2 (R = -0.74 ± 0.17). The WM showed a similar progressive, but non-significant, decrease in the relaxation rates, with an increase in oxygen intake (P = 0.055). The Hill's model predicted a maximum R2* response of the GM, of 3.5%, with half the maximum at 68% oxygen concentration. Conclusions: The GM-R2* responds to hyperoxia in a concentration-dependent manner, suggesting that monitoring and modeling of the R2*-response may provide new oxygenation biomarkers for tumor therapy or assessment of cerebrovascular reactivity in patients.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Diagnostic and Interventional Radiology
04 Faculty of Medicine > University Hospital Zurich > Clinic for Neuroradiology
04 Faculty of Medicine > Institute of Biomedical Engineering
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2015
Deposited On:30 Jan 2015 15:41
Last Modified:03 Aug 2017 16:41
Publisher:Medknow Publications
ISSN:2156-5597
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.4103/2156-7514.150439
PubMed ID:25806136

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