title: Agreement and repeatability of vascular reactivity estimates based on a breath-hold task and a resting state scan.
abstract: FMRI BOLD responses to changes in neural activity are influenced by the reactivity of the vasculature. By complementing a task-related BOLD acquisition with a vascular reactivity measure obtained through breath-holding or hypercapnia, this unwanted variance can be statistically reduced in the BOLD responses of interest. Recently, it has been suggested that vascular reactivity can also be estimated using a resting state scan. This study aimed to compare three breath-hold based analysis approaches (block design, sine-cosine regressor and CO2 regressor) and a resting state approach (CO2 regressor) to measure vascular reactivity. We tested BOLD variance explained by the model and repeatability of the measures. Fifteen healthy participants underwent a breath-hold task and a resting state scan with end-tidal CO2 being recorded during both. Vascular reactivity was defined as CO2-related BOLD percent signal change/mmHg change in CO2. Maps and regional vascular reactivity estimates showed high repeatability when the breath-hold task was used. Repeatability and variance explained by the CO2 trace regressor were lower for the resting state data based approach, which resulted in highly variable measures of vascular reactivity. We conclude that breath-hold based vascular reactivity estimations are more repeatable than resting-based estimates, and that there are limitations with replacing breath-hold scans by resting state scans for vascular reactivity assessment.
authors: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, UK; MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, UK.
authors: Ilona
authors: I
authors: Lipp
authors: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, UK.
authors: Kevin
authors: K
authors: Murphy
authors: MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, UK.
authors: Xavier
authors: X
authors: Caseras
authors: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, UK. Electronic address: wiserg@cardiff.ac.uk.
authors: Richard G
authors: RG
authors: Wise
mesh_terms: D000328:Adult; D001808:Blood Vessels / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008959:Models, Neurological; D010100:Oxygen / Q000097:blood; D015203:Reproducibility of Results; D012119:Respiration; D012146:Rest / Q000502:physiology*; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: Breath-hold; RSFA; Repeatability; Resting state; Vascular reactivity