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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:

The 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'