diff --git a/src/caosadvancedtools/cfoods/bids/datastructure.py b/src/caosadvancedtools/cfoods/bids/datastructure.py
index bec55ddb80ab95569abf1ab5e258ef7fb774e307..31420f61650b8f84c142d6dfd536d09b7ef4351f 100644
--- a/src/caosadvancedtools/cfoods/bids/datastructure.py
+++ b/src/caosadvancedtools/cfoods/bids/datastructure.py
@@ -27,4 +27,8 @@ class BIDSStructure(object):
     bidsfolder_pattern = (r".*/(?P<bids_folder_name>((?!/).)*)/")
     date_pattern = r"(?P<date>\d{2,4}[-_]\d{1,2}[-_]\d{1,2})"
     date_suffix_pattern = r"(_(?P<suffix>(((?!/).)*)))?/"
+    subject = r"(sub-(?P<subjectno>\d*)/)"
+    session = r"(ses-(?P<sessionno>\d*)/)?"
+    data = r"(anat|eeg|meg)/"
+    ni_file = bidsfolder_pattern+subject+session+data+r"(.*\.nii\.gz)"
     dataset_description = bidsfolder_pattern+r"dataset_description\.json$"