coregistration_images   Create a vector of the corregistered images
                        based on the available MRI images modalities.
create_bias_list        Create a vector of inhomogeneity corrected
                        images based on the available MRI images
                        modalities.
get_modalities          Create a vector of strings with the MRI
                        modalities available in a patient's folder.
image_normalization_ravel
                        Wrapper function for RAVEL normalization of
                        T1-weighted images
load_mri_group          Load MRI per group or disease
load_mri_patient        Load MRI scans per patient
preprocess_modalities   Preprocess group of MRI scan for one patient
preprocess_modality_t1
                        Preprocess T1-weighted MRI scan for one patient
preprocess_patients     Preprocess MRI scans for multiple patients
