Spatiotemporal dynamics of CBF and BOLD fMRI responses to breath-hold challenges

Joana Carolina Sequeira

Key information

Authors:

Joana Carolina Sequeira (Joana Carolina Sequeira Pinto)

Supervisors:

Pedro Vilela (Pedro Vilela); Patrícia Margarida Piedade Figueiredo (Patrícia Figueiredo)

Published in

11/28/2012

Abstract

The study of cerebrovascular reactivity is important for the evaluation of neurological diseases. Functional magnetic resonance imaging (MRI) techniques are currently being explored for this purpose, namely the Blood Oxygenated Level-Dependent (BOLD) contrast and the Arterial Spin Labelling (ASL) cerebral blood flow (CBF) contrast. In this work, we aimed to characterize the spatiotemporal dynamics of both ASL and BOLD responses to breath-holding (BH) challenges. A group of 7 healthy subjects were studied on a 3T MRI system using two BH protocols (with and without preparatory inspiration). Optimal BOLD and ASL data were acquired and BOLD, BOLDASL and CBF contrasts were obtained. Data were analysed based on a general linear model using two approaches (Sine Delay Optimization (SDO)/Sine Cosine Linear Combination (SCC)). The amplitude of cerebrovascular reactivity (CVR) and the associated cerebrovascular delays (CVD) were estimated for each contrast/BH protocol. Both SDO and SCC models were successful in obtaining CVR and CVD values/maps. However, SCC yielded CVR and CVD voxelwise and showed greater sensitivity for BOLD and BOLDASL responses. The CBF data showed larger CVD variations relative to BOLDASL data. The BH protocol with preparatory inspiration led to larger values of CVD and the corresponding time courses showed a more complex shape relative to the BH protocol without inspiration. In conclusion, we implemented a modelling approach that allows estimation of CVR and CVD voxelwise. Although BOLD data have been analysed in similar ways, to our knowledge, this is the first study of the spatiotemporal dynamics of ASL BOLD and CBF data.