Welcome to the fMRI Phantoms Project at Vanderbilt University

This site is supported in part by NIH/NINDS NS046077 "Computer-Generated Phantoms for FMRI Evaluation". It is designed to provide distribution of phantoms that can be used for evaluation of postprocessing software used in FMRI analysis.

The site is an ongoing project of the Vanderbilt Institute of Imaging Science (VUIIS), the Department of Radiology and Radiological Sciences of Vanderbilt University School of Medicine, and the Department of Electrical Engineering and Computer Science of Vanderbilt University School of Engineering.

There are four categories of motion available. Phantoms have been built using all of these motion categories (Set 1, 7 mm slices), some of these motion categories (Set 2, 4.5 mm slices), or one motion category (Set 3, simulator-produced phantoms). For each category, plots of motion are included on the page where distribution of the phantom is available. Set 1 and Set 2 are built using real subject data to which specific motion characteristics from real subjects are applied. Set 3 uses our unique MR simulator to create phantoms in which all aspects of the image production process are controlled, including the addition of susceptibility artifacts. Phantoms built using the simulator use real motion characteristics from volunteer subjects as well. The pre-built phantom sets are a works-in-progress and will be expanded as new phantoms are developed.

The phantom file format is NIfTI-1, a format for distribution of FMRI data sets. A description can be found at http://nifti.nimh.nih.gov/. Conversion utilities for NIfTI-1 format data to other formats are described on the AVWUTILS webpage that is part of FSL, an fMRI processing package (http://www.fmrib.ox.ac.uk/fsl/). A set of libraries for use with Matlab© and other languages is available at http://niftilib.sourceforge.net/. All phantoms are in .nii.gz form, a gziped version of the NIfTI-1 format. gzip is available from www.gzip.org. Raw binary 4D files are also available, stored slice by slice by time point, two bytes/pixel, big-endian, uncompressed. Analyze© format is available as tar files.

There are several variations of pre-generated fMRI phantoms available for download, which provide different motion characteristics and different specification of the image information. The Mask available with each phantom set is a 3D volume that contains the location of the activation areas used in the particular data set. The time course is the block paradigm used to build the phantoms in that data set. The images are in radiological format (subject's left on the right side of the image).

Our phantoms were built to permit quick testing of new algorithms or to enhance a student's learning experience while becomming familiar with fMRI processing software. We recognize that there are limitations to the current pre-generated sets. However, there are many additional capabilities that we hope to add to these phantoms and this site. Please look at custom phantoms: future capabilities for some of these planned additions.

There are several publications describing different aspects of our project that are available through the following links. There is a presentation that describes the original goals of the project at the time of initial funding that can be downloaded as a pdf. There are three abstracts from ISMRM2006 that are available: 1) an overview of the extended phantoms, 2) an approach to correcting distortions in EP images, and 3) modeling of susceptibiltiy artifacts. There is an ISMRM2006 poster presentation that describes our current work on modeling motion-induced susceptibility artifacts. There are three papers available here as pre-prints, which were presented at the SPIE Medical Imagiing Conference 2006, that discuss specific details of the work that is continuing for development of our phantoms.

If you find this site helps in your work or if you would like to give us suggestions for improvements, please visit our Comments and Suggestions page. Our funding depends in part on how these phantoms are used by the fMRI community.