The Flywheel hierarchy
Understanding how Flywheel organizes data is helpful for understanding where scans go or for curating data into BIDS format.
Typically, you do not need to manually create the organizational structure within a project. Instead, Flywheel reads a file's header information to group and organize relevant data within a project. Learn more about how Flywheel uses file header information like DICOM tags to organize data and extract metadata or learn more about how to import data.
The table below describes how Flywheel is organized at the highest level (site) all the way down to the lowest granularity (files).
| Level | Description |
|---|---|
| Site | Your institution's Flywheel installation |
| Group | The PI, Lab, or virtual team |
| Project | An experiment or other collection of data |
| Subject | A research participant/patient, animal or phantom |
| Session | A subject’s visit or interaction with a modality to perform an evaluation (for example an MRI scan or a Doctor’s visit) |
| Acquisition | Unit of data collected during a session (for example a T1 Weighted sequence or a tasked-based EEG ) |
| Files | Files can be attached to projects, subjects, sessions, and acquisitions. The files are usually related to the level to which you attach them. For example, at the acquisition level, files are the actual scan files. On a project, you can attach a CSV list of the study participants, or attach exam results directly to the subject. |
The core organization is strictly enforced. For example, each group includes one or more projects. Within the project are subjects with sessions. Sessions cannot be directly attached to the group. You must create groups and projects before adding data to Flywheel.