**SUMMARY**

***First NIfTI Data Format Working Group Meeting***

***July 11 & 12, 2002***

*Conference Rooms B1/B2, Neuroscience Center*

*6001 Executive Boulevard*

*Rockville, Maryland*

**I PURPOSE**

The Data Format Working Group (DFWG) was established in response to
specific recommendations made at two previous workshops held under the
auspices of the Neuroimaging Informatics Technology Initiative (NIfTI).
In those workshops, the use of a variety of different formats for
functional magnetic resonance (fMRI) data by the research community was
identified by tool-users and tool-developers as the major cause of a
host of problems impeding progress in this important area of
neuroimaging.

In accord with the recommendations from those workshops, the membership
of the DFWG draws from research groups that are highly active in
developing informatics tools for fMRI data, and it is charged with
arriving at a technical solution to the problems engendered by the use
of multiple, diverse, and evolving fMRI data formats. The DFWG,
therefore, represents a community-based approach to solving a widespread
problem in fMRI research.

The purpose of this meeting was to begin the process of identifying
needs, constraints, and opportunities related to pursuit of this
solution. The nature and range of problems were to be defined in the
context of community goals. Priorities for addressing particular
problems were to be discussed, and existing solutions to these problems
were to be explored. Finally, immediate next steps in the process of
arriving at a technical solution to the problem of multiple data formats
were to be identified.

**II BACKGROUND**

The use of neuroimaging to study the structure and function of the human
brain has opened unprecedented vistas of understanding of this most
complex and important organ. Among neuroimaging approaches to study
brain function, fMRI stands out due to its versatility, compatibility
with other key magnetic resonance imaging modalities, and its
non-invasive nature. Not surprisingly, the use of fMRI has been embraced
by neuroscientists and has greatly accelerated our understanding of the
human brain in health and disease.

As neuroscience labs have developed and adapted fMRI technology, they
have come to use a wide array of different formats for their fMRI data.
And, as the use of fMRI has spread, so too have informatics tools that
were written in particular labs to make sense and use of neuroimaging
data. Such informatics tools perform functions like: spatial
normalization, modeling the hemodynamic response, statistical analyses
in space or time domains, data visualization, image segmentation,
feature extraction, noise suppression, etc. Although different tools
have been developed in different labs to perform the same function, it
is significant to note that different tools seeking to accomplish the
same goal (e.g., model the hemodynamic response) often do so in
different ways. This means that the same input to the processing streams
of different tools (that are supposedly performing the same function)
can give rise to different outputs. Finally, each such informatics tool
does not accommodate all data formats, so the data format in which the
fMRI data are instantiated plays a big role in determining which
informatics tool is used to subsequently process the data.

The fact that a given tool accepts a limited range of data formats
together with the fact that different tools process the same data in
different ways (and give different outputs) has several significant,
negative consequences for fMRI-based neuroscience research. First, tools
are not interoperable with each other, so the data format limitation
places practical limitations on the manner in which fMRI data are
processed and explored---these limits to scientific inquiry are,
therefore, imposed for reasons not driven by science. Second, rigorous
comparison of tools is not possible---whether one tool is better than
another for a particular task, for example, is a straightforward
question without a straightforward answer. Third, rigorous comparison of
the neuroscientific results obtained in different labs using different
tools is not possible---so when results differ across studies, it is not
clear whether this finding is adding to our knowledge of brain function
or merely an epiphenomenon of the software used to process the data.

Large labs with ample resources have overcome these obstacles by
investing in programming capability and programming around them (e.g.,
writing software to convert data from one format into another), but a
large number of labs do not have such resources at their disposal, and
are greatly constrained by these circumstances. While there are several
possible avenues through which to remove the constraints described
above, members of the tool-developer and tool-user communities
recommended that the best initial approach would be to establish a
technical solution to the use of different fMRI data formats. A
technical solution would have the potential of broadening the range of
tools that could be used for processing data from a given study, and
allow the rigorous comparison of the tools and, most importantly, of the
neuroscientific results of fMRI studies.

To accomplish this, the NIMH and the NINDS, joint sponsors of NIfTI,
convened the DFWG which comprises 11 experts who are deeply involved
with development of informatics tools that are used widely by the fMRI
research community. The DFWG is chaired by Stephen Strother (University
of Minnesota, Minneapolis), and its members are: John Ashburner
(Functional Imaging Laboratory, London), Robert Cox (NIMH Intramural
Research Program, Bethesda), Kate Fissell (University of Pittsburgh),
Rainer Goebel (Universiteit Maastricht), Christian Haselgrove
(Massachusetts General Hospital, Charlestown), Colin Holmes (Silicon
Graphics, Inc., Mountain View), Jack Lancaster (University of Texas
Health Science Center, San Antonio), David Rex (University of
California, Los Angeles), Stephen Smith (Oxford University Centre for
Functional MRI of the Brain), and John Van Horn (Dartmouth College,
Hanover). The DFWG is expected to meet several times over the next year,
as well as communicating regularly via electronic means.

It is important to emphasize that at the outset of this activity, there
was no preconceived notion of the form that the technical solution might
take. Also important to emphasize is the fact that the technical
solution arrived at by the DFWG will not be imposed upon the research
community, but will be offered as a way to address the problems caused
by the diversity of data formats in fMRI. Still, several groups
responsible for developing fMRI informatics tools have already indicated
their willingness to take advantage of such a solution in future
software. Therefore, the DFWG has the potential to have a significant
impact in this area.

**III DISCUSSION and FINDINGS**

In the months preceding this inaugural meeting, members of the DFWG
authored and circulated among themselves documents that provided their
initial thoughts on the problem of multiple fMRI data formats. Papers
were submitted both by those who were planning to attend as well as
those who were unable to attend.

The meeting, itself, commenced with a morning of presentations. The
first, by Michael Huerta, gave an overview of NIfTI and the charge to
the DFWG. A series of presentations followed to provide technical
orientation and provoke discussion, with Robert Cox presenting "XML's
Role in AFNI and Beyond," Kate Fissell presenting "Format Needs for
Fiswidgets with Comment on ANALYZE," David Rex presenting "Data Format
Needs of the LONI Software Pipeline," and Colin Holmes presenting
"Origins and Capabilities of MINC with Comment on Industry's
Perspective."

Over the course of the next day and a half, meeting participants
discussed the range of problems caused by the use of multiple, diverse,
and evolving data formats used in fMRI research, how these problems
related to overarching goals of the fMRI research communities, and which
problems should be given priority attention. Also discussed were whether
solutions exist in whole or part to particular problems, and what steps
should be taken next. The major findings and related action items that
resulted from these discussions are summarized below.

-   **Number and nature of existing data formats used by the fMRI
    research community** Despite the expertise and experience assembled
    at this meeting of the DFWG, it was clear that the full range of
    formats used in fMRI research was uncertain. Nevertheless, a
    systematic collection of different formats was considered by members
    of the DFWG as having importance for the fMRI research community at
    large for many reasons, as well as having importance to the DFWG in
    helping to identify next steps in the pursuit of a technical
    solution. The members of the DFWG volunteered to gather information
    about various formats; ultimately, this information will be compiled
    and disseminated on the NIfTI web site for use by the entire fMRI
    research community.

-   **Number and nature of existing data format converters used by the
    fMRI research community** Many labs have written converters to move
    data from one format to another. How many such converters exist, and
    the details of their operation are not widely known, however. Since
    robust format converters with high fidelity in the conversion
    process would be extremely useful in addressing the problem of
    multiple data formats in the very near term, the DFWG volunteered to
    gather information systematically about existing converters. This
    information will then be compiled and disseminated on the NIfTI web
    site for the benefit of the entire fMRI research community.

-   **Simple data formats versus complex data formats** The advantages
    and disadvantages of simple versus complex data formats was
    discussed at length by the DFWG. It was determined that both levels
    of complexity are useful. With this in mind, the DFWG decided to
    form two subgroups to discuss how existing simple and complex data
    formats might be enhanced and made available to the fMRI community
    at large. In addition, the idea of developing a robust and
    well-characterized converter between two such data formats was
    advanced as a way to facilitate problems of using different formats.
    These subgroups volunteered to draft documents that would outline
    how to enhance an existing simple format and an existing complex
    format. Drafts of these documents will be posted on the NIfTI web
    site, and comments on them will be solicited from the fMRI research
    community.

-   **Metadata and design matrix information** An important component of
    data formats is the manner in which they address metadata. Since
    there is a range of opinions, however, about what constitutes
    metadata, the DFWG decided to draft a document addressing key
    issues. An aspect of particular interest to the members of the DFWG
    was the manner in which information about the experimental design be
    incorporated into the format; that is, how to generate a design
    matrix within a data format. A subgroup of DFWG will draft a
    document on metadata, with design matrix information considered in
    particular. This will ultimately be posted on the NIfTI web site for
    information to the fMRI research community

The DFWG decided to remain engaged electronically as these action items
are carried out over the next several months, and will meet again in the
first half of calendar year 2003.

**IV PARTICIPANTS**

Stephen C. Strother (Chair)

V A Medical Center

International Neuroimaging Consortium (11P)

One Veterans Dr

Minneapolis, MN 55417

Tel: 612-725-2000 x4790

Email: <steve@neurovia.umn.edu>

Kate Fissell

University of Pittsburgh, LRDC

3939 O\'Hara St.

Pittsburgh PA 15260

Tel: 412-624-5279

Fax: 412-624-9149

Email: <fissell+@pitt.edu>

Christian Haselgrove

Center for Morphometric Analysis

Massachusetts General Hospital

Building 149, 13th St.

Charlestown, MA 02129

Tel: 617-726-6018

Email: <ch@cma.mgh.harvard.edu>

William Heetderks

National Institute of Neurological Disorders

and Stroke

6001 Executive Blvd., Room 2207\
Bethesda, MD 20892\
Tel: 301-496-1447\
Fax: 301-480-1080\
Email: <heet@nih.gov>

Colin J Holmes

Silicon Graphics, Inc.

SGI 41-3-405, 1600 Amphitheatre Pkwy

Mountain View CA 94043-1351

Tel: 650-933-7512

Fax: 650-932-0332

Email: <cholmes@engr.sgi.com>

Michael F. Huerta

National Institute of Mental Health

6001 Executive Blvd., Room 7202

Bethesda, MD 20892-9645

Tel: 301-443-3563

Fax: 301-443-1731

Email: <mhuerta@helix.nih.gov>

Jack L. Lancaster

Department of Radiology

Research Imaging Center

University of Texas Health Science Center

7703 Floyd Curl Drive

San Antonio, TX 78229-3900

Tel: 210-567-8100

Fax: 210-567-8152

Email: <jlancaster@uthscsa.edu>

Yuan Liu

National Institute of Neurological Disorders

and Stroke

6001 Executive Blvd., Room 2110B

Bethesda, MD 20892-9523

Tel: 301-496-3108

Email: <liuyuan2@ninds.nih.gov>

David E. Rex

Laboratory of Neuro Imaging

Department of Neurology, Room 4-238

710 Westwood Plaza

Los Angeles, CA 90095-1769

Tel: 310-206-2101

Fax: 310-206-5518

Email: <drex@loni.ucla.edu>

Stephen M. Smith

Oxford University Centre for Functional MRI of the Brain

John Radcliffe Hospital, Headington,

Oxford OX3 9DU, UK

Tel: +44 (0) 1865 222726

Fax: +44 (0) 1865 222717

Email: <steve@fmrib.ox.ac.uk>

<http://www.fmrib.ox.ac.uk/~steve>

John D. Van Horn

Center for Cognitive Neuroscience

Dartmouth College

6162 Moore Hall

Hanover, New Hampshire 03755

Tel: (603)646-2909

Fax: (603)646-1181

Email: <John.D.Van.Horn@dartmouth.edu>

**V DFWG MEMBERS UNABLE TO ATTEND**

John Ashburner

Functional Imaging Laboratory

12 Queen Square

London WC1N 3BG, UK.

Tel: +44 (0)20 78337491 or +44 (0)20 78373611 x4381

Fax: +44 (0)20 78131420

Email: <john@fil.ion.ucl.ac.uk>

<http://www.fil.ion.ucl.ac.uk/~john>

Rainer Goebel

Department of Neurocognition

Faculty of Psychology

Universiteit Maastricht

Maastricht, Netherlands

Tel: +31 43 3884014

Email: <R.Goebel@Psychology.Unimaas.Nl>