Regional quantification of cerebral venous oxygenation from MRI susceptibility during hypercapnia

Publication date: 1 January 2015 Source:NeuroImage, Volume 104 Author(s): Audrey P. Fan , Karleyton C. Evans , Jeffrey N. Stout , Bruce R. Rosen , Elfar Adalsteinsson There is an unmet medical need for noninvasive imaging of regional brain oxygenation to manage stroke, tumor, and neurodegenerative diseases. Oxygenation imaging from magnetic susceptibility in MRI is a promising new technique to measure local venous oxygen extraction fraction (OEF) along the cerebral venous vasculature. However, this approach has not been tested in vivo at different levels of oxygenation. The primary goal of this study was to test whether susceptibility imaging of oxygenation can detect OEF changes induced by hypercapnia, via CO2 inhalation, within selected a priori brain regions. Ten healthy subjects were scanned at 3T with a 32-channel head coil. The end-tidal CO2 (ETCO2) was monitored continuously and inspired gases were adjusted to achieve steady-state conditions of eucapnia (41±3mmHg) and hypercapnia (50±4mmHg). Gradient echo phase images and pseudo-continuous arterial spin labeling (pcASL) images were acquired to measure regional OEF and CBF respectively during eucapnia and hypercapnia. By assuming constant cerebral oxygen consumption throughout both gas states, regional CBF values were computed to predict the local change in OEF in each brain region. Hypercapnia induced a relative decrease in OEF of −42.3% in the straight sinus, −39.9% in the internal cerebral veins, and a...
Source: NeuroImage - Category: Neuroscience Source Type: research