Vessel contrast in Susceptibility Weigthed Imaging (SWI) under inhalated anesthesia with different oxygen pressure

Introduction Susceptibility weighted imaging (SWI) has been used to depict the structure of the cerebral vascular system [1, 2]. However, it has not been much extended in small animal imaging. During the MRI exam, animals are anaesthetized, which makes the venous contrast vary not only according to the depth of anaesthesia [3], but also to the oxygen pressure in the supplied gas when using inhaled anaesthesia. SWI signal is based on the tissue susceptibility differences, which are related to blood oxygenation [4], and therefore using anaesthetics along with pure oxygen for animal sedation can lead to a loss of contrast of cerebral veins in SWI. The purpose of this study was to investigate how the oxygen pressure in the supplied gas affects the venous contrast in SWI in order to study the microvasculature of the rat brain.