Make_CVR_reg_physio brick¶

Generate the physiological regressor for cerebrovascular reactivity evaluation¶

The regressor generated is end-tidal carbon dioxide (ETCO2) as a function of the dynamics (repetition of scans). It can be used as part of a general linear model (GLM) or similar analysis, to assess the relationship between variations in ETCO2 and cerebral blood flow in regions of interest.
ETCO2 data are pre-processed and then convolved with a canonical hemodynamic response function (HRF) to create a regressor that accounts for the hemodynamic response to variations in CO₂ levels.
The brick accepts physiological parameter files in .csv (Magdata) or .log (CoolTerm) format and trigger files in .txt, .log or .csv format.
The Make_CVR_reg_physio brick generates a standard (average) regressor if the physiological parameter and trigger files are not supplied or are corrupt. Otherwise, an individual regressor is generated.

Standard regressor:

Inputs parameters:

func_file

T2* functional Magnetic Resonance Imaging (fMRI) experiment recorded during the hypercapnic Challenge (only required to extract metadata from the functional image). An existing, uncompressed file (valid extensions: [.img, .nii, .hdr]).

ex. ['/home/username/data/raw_data/func.nii']

trigger_data
The trigger data, to ensure that ETCO2 data are synchronized with imaging data. An existing file, exclusively in [.txt, .csv, .log] format.
ex. '/home/username/data/downloaded_data/vaso_trigger_time.log'
physio_data
The physiological data, including ETCO2 levels, measured during the neuroimaging scan. An existing file, exclusively in [.txt, .csv] format.
ex. '/home/username/data/downloaded_data/physio_data.csv'

Outputs parameters:

cvr_reg
The output generated regressor. A file with .mat format.
ex. '/home/username/data/derived_data/CVR_physio_reg.mat'