Data from the Open Access Series of Imaging Studies (OASIS) is now available on XNAT Central! The OASIS project is aimed at making neuroimaging datasets freely available to the scientific community.

More information about these studies can be found at

The OASIS Datasets

There are 3 OASIS datasets that can be viewed and downloaded on XNAT Central. The data from these projects should not be combined - Each dataset should not be used individually only, as there may be overlap across the different studies.

OASIS-1 consists of cross-sectional MRI data from 434 scan sessions across 416 different subjects. It was made available in 2007.

OASIS-2 consists of longitudinal MRI data from 373 scan sessions across 150 subjects. It was made available in 2010.

OASIS-3 consists of both cross-sectional and longitudinal MRI and PET data across 1098 subjects. It was made available in 2018.

OASIS-3 is the newest release of data. It includes MR and PET scan data in the BIDS format, which consists of a NIFTI (.nii or .nii.gz) file plus a corresponding JSON (.json) file. Also included in OASIS-3 are Freesurfer output files and output from the Pet Unified Pipeline (PUP). More details about use of BIDS, Freesurfer, and PUP can be found in the OASIS-3 Data Dictionary.

Accessing OASIS Data

To access datasets from any of the three OASIS projects, you must first sign the data use agreement located at Within one week of completing this form, you will be sent an invite to XNAT Central at the email address you provided. You can then follow the XNAT Central sign-up process and view the data. If you already have an XNAT Central account at your provided email address, you will be granted access to the OASIS-1, 2, or 3 projects on Central, depending on what you selected in the data use agreement form.

Note: Requesting OASIS project access directly from XNAT Central will not enable you to access the data immediately. You must fill out the data use agreement to receive project access.

Viewing Data from the Project Page

When you visit a project page for an OASIS project on XNAT Central, you will see a table of the various subjects in the project. Clicking on other tabs will display MR scan sessions, PET scan sessions, Freesurfer or PUP (PET processing) sessions. Shown below is an example of the MR Session listing.

If you click on the "Options" button (outlined in red below) you will see a list of options for the data listing. 

Options → Spreadsheet will enable you to download the current table in a .csv (comma-separated) spreadsheet format.

Options → Edit Columns will display a column editor window that enables you to select which columns to display in the table. 

The list on the left contains the currently visible columns. The list on the right contains the fields available to be added to the current list. Use the left and right arrows in the center to move fields between the lists, and use the up and down arrows on the left side to rearrange fields in the Current Fields listing. Press Submit to display the results. 

Note: Not all fields listed under Available Fields will have data to display. For example, OASIS data does not contain tumor information, so the field "Custom Field:tumorlocation" will always be blank.

Downloading Data Using the Website

Note: We have been experiencing intermittent issues with this download method. If you experience problems with this method, please see Downloading Data Using the Command Line.

OASIS data can be downloaded directly from the XNAT Central website using your web browser. For more information, see How To Download Image Data From XNAT Projects.

Downloading Data Using the Command Line

OASIS data can be downloaded via the command line. This can be useful if you'd like to use scripts to automate downloading or organize files.

For a sample script to download individual MR scans from XNAT Central, visit the oasis-scripts repository on Github.

More advanced users can write their own scripts to download data from XNAT Central via the REST API. For more details on using the XNAT REST API to download scan data and processed image data, see How To Download Files via the XNAT REST API.