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Continuous noninvasive monitoring of transcutaneous blood gases for a stable and persistent BOLD contrast in fMRI studies in the rat
Author(s) -
RamosCabrer Pedro,
Weber Ralph,
Wiedermann Dirk,
Hoehn Mathias
Publication year - 2005
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.978
Subject(s) - functional magnetic resonance imaging , anesthesia , somatosensory system , blood oxygen level dependent , capnography , oxygenation , magnetic resonance imaging , blood oxygenation , medicine , blood pressure , arterial blood , partial pressure , biomedical engineering , carbon dioxide , nuclear medicine , oxygen , chemistry , radiology , organic chemistry , psychiatry
The physiological status of anesthetized rats greatly influences blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI). Monitoring of physiological parameters, particularly partial pressure of carbon dioxide (pCO 2 ) levels in the blood, is therefore an important part in the design and performance of reliable fMRI experiments. In this paper, the use of a transcutaneous blood gas analyzing system in rats as a completely noninvasive and MR‐compatible method is demonstrated. It was successfully used to monitor continuously pCO 2 values, as an effective alternative to more invasive methods, such as analysis of repetitive arterial blood samples or endtidal capnography. In addition, the transcutaneous pCO 2 of rats anesthetized for long periods was studied using different anesthetic substances and experimental protocols. On‐line monitoring of pCO 2 values permitted experimental conditions to be established in which the animals remained normocapnic and during which a robust and consistent BOLD contrast could be observed upon somatosensory forepaw stimulation. A transcutaneous pCO 2 threshold level was defined for the reliable detection of a stimulus‐dependent BOLD response. Copyright © 2005 John Wiley & Sons, Ltd.