by Joseph A. Frank, M.D., OD; Ronald Levin, Sc.D., NCRR; Margaret Douglas, DCRT; and Geoff Sobering, Ph.D., Pulsar Corp.

We read with great interest Dr. Gallin's recent editorial in The NIH Catalyst (November-December 1994), in which he mentioned that digitized images such as X-rays will soon be available on desktop computers in the Clinical Center. With our Multimodality Radiology Image Processing System (MRIPS) recently coming on line, Dr. Gallin's vision of having images displayed on a researcher's desktop computer has become a reality.

Since mid-February, MRIPS has been capturing all images from NIH's General Electric and Picker magnetic resonance (MR) and computerized tomography (CT) scanners without operator intervention. We are also poised to automatically capture images from the NIH MIRAGe system at the Clinical Center's Nuclear Medicine (NM) and Positron Emission Tomography (PET) departments.

Within an hour after completion of an MR or CT exam, the images, including the header descriptive information, are available to a researcher via the MRIPS Data Registry. Access to data on the MRIPS servers is protected by multiple levels of security. Only researchers with authorization from their clinical director may access clinical examinations. At the researcher's request, data access may be restricted to the principal investigator or the principal investigator's work group. Beyond those levels of security, the data are secured with password protection.

Retrieval of these images is possible from either UNIX workstations (HP, DEC, SUN, and SGI) or Macintosh or PC systems that support a local X-windows server. The images from CT, MRI, or NM/PET can be viewed and analyzed by any of the many image processing software packages supported by MRIPS. These packages, which are available to researchers at no additional cost, include MEDx, Analyze, IDL, and PV-Wave. Once access is granted by the MRIPS Data Registry, a data set may be read, viewed, and analyzed using NIH's Image version 1.57 software on any Macintosh via the AFP/AFS (AppleTalk Filing Protocol/Andrew File System) Translator maintained by MRIPS. Because MRIPS is supported by the management fund, individual researchers are not charged for the costs of disk space on the MRIPS file servers.

The MRIPS data registry greatly facilitates access to clinical images, conversion of images from one format to another, and simultaneous analysis of 3-D volumes of images from multiple modalities. The software package MEDx, designed for MRIPS specifically for the NIH clinical-imaging research community, includes several well-known algorithms used for brain registration, including the Chen/Pelizzari algorithm. This has been particularly useful in the registration of MRI to PET data, and for functional MRI studies of high-resolution anatomical images.

The MEDx toolbox is available to any member of the NIH intramural community. MEDx can be run on your Advanced Laboratory Workstation (ALW) by executing the command /afs/.nih/od/MRIPS/bin/medx. MEDx was created to handle large imaging data files (e.g., 200- to 500-megabyte data sets obtained with functional MRI). Therefore, to run MEDx efficiently on your workstation, you need the following configuration: 1) at least 64 megabytes (preferably 128 megabytes) of physical random-access memory (RAM), 2) preferably two 1-gigabyte disks, one for UNIX and one for the AFS cache, and 3) both a shared memory kernel (with at least 32 segments and 32 megabytes per segment) and a shared memory X-server should be activated on the workstation. To get the shared memory resources activated on the ALW, submit a problem trouble report, or "ptr," asking for a "MEDx" kernel. In the ptr, please tell the ALW support staff the amount of physical memory and the type of graphics card installed on the workstation.

In response to the overwhelming storage demands of the imaging community, MRIPS in the future plans to expand magnetic disk storage to about one terabyte. This increase should allow storage of all CT, MRI, and PET data obtained in the Clinical Center over the course of a year. MRIPS servers are already using a high-speed, 100-megabyte/sec FDDI (fiber optic) network and are fully forward compatible with future development of high-speed data and video transmission, such as asynchronous transfer mode (ATM).

For more information, contact MRIPS support staff (phone: 402-6000; e-mail: medxbugs@
list.nih.gov). There is also a MRIPS tutorial every Friday at 12:30 p.m. in the Laboratory of Diagnostic Radiology Research, Building 10, Room B1N256. A summary of the weekly tutorials and details about MRIPS may also be obtained from the MRIPS World Wide Web server (http://www-mrips.od.nih.gov/).

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