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May 22, 2006

PACS & Nuclear Medicine — Slowly Coming Together
Radiology Today
Vol. 9 No. 10 P. 28

Are any of these challenges in your imaging department or facility?

• The rapid growth of PET/CT

• Extending PACS coverage throughout the enterprise

• Bringing nuclear medicine, ultrasound, endoscopy, and other non-DICOM images onto the PACS

• Adding fusion imaging, 3-D, nuclear medicine, and other capabilities to standard PACS workstations and relying on fewer dedicated workstations

• Incorporating images into an electronic medical record that can be accessed throughout the organization, and eventually, from outside it

These issues will fill the futures of imaging informatics pros, but the United States remains a country where many x-rays are still done on film and nuclear medicine is still filled with largely proprietary systems operating separately from the PACS—if any digital archive is even in place yet. In most places, the real world integration of nuclear medicine and PACS is a ways off. But, that’s not to say many people aren’t working on it.

Market Forces
Like most industries, PACS companies respond to their market. Until a few years ago, there was little demand for handling nuclear medicine images in PACS, which was largely designed to handle CT and MR images. Many facilities use PACS to archive CT and MR but still used film for x-rays. As that changes and more facilities seek to go completely digital, more companies will get involved. The Society of Nuclear Medicine (SNM), which was involved with a nuclear medicine PACS standard called the Nuclear Medicine Imaging Profile, suggests that imaging departments nudge that process. On its society Web site, SNM suggests asking PACS and gamma camera vendors whether they support the Integrating the Healthcare Enterprise Nuclear Medicine Imaging Profile. Doing so will raise demand, nudging industry to improve PACS capability for nuclear medicine.

There are three basic PACS industry approaches for bringing nuclear medicine into the PACS fold:

1. Secondary DICOM capture. At the Society for Computer Applications in Radiology (SCAR)—which changed its name to the Society for Imaging Informatics in Medicine (SIIM)—meeting, much of the nuclear medicine PACS capability displayed was based on secondary capture of non-DICOM images. Various systems enable any medical image regardless of format to be converted to a static DICOM image for storage and display on a PACS network.

“If a facility has equipment that’s more than five years old, more than likely it’s non-DICOM,” said Tony Molinari, product manager for Foresight Imaging, maker of the TIMS System for converting non-DICOM images to DICOM. “Using our system, you can extend the life of that equipment three to five years.”

Molinari pointed out that facilities making the transition to digital imaging often have to replace modalities at the same time they are investing in PACS. Molinari said the $14,000 to $17,000 investment in his system allows the imaging facility to put off and spread out modality purchases.

“Our value proposition is that if you’re spending a lot of money on PACS, we can extend the life or your modalities three to five years,” he said.

Cost and the ability to archive images on a PACS are obviously important considerations, but secondary capture isn’t necessarily a nuclear medicine PACS. Secondary capture doesn’t display motion or capture other important patient information and DICOM header data that would come from DICOM devices. As such, it has archiving value but does not truly bring nuclear medicine into a PACS-like workflow.

2. Partnering with a specialty company. At SCAR/SIIM, many PACS companies talked about their partnerships with companies that specialize in integrating nuclear medicine and other images into PACS.

“You can’t be good at everything,” said Andy Nelson, chief financial officer of MIMvista Corp., which focuses on fusion imaging and broader nuclear medicine functionality. “The easiest way for PACS companies is to bring in a third party’s software that they can attach to their PACS.”

While PET/CT may be MIMvista’s focus, its MIMcardiac provides analysis of perfusion and function for SPECT studies. The software also compares stress and rest images and creates normalized subtraction images from aligned cardiac images. The subtraction images highlight perfusion differences and perfusion/metabolism mismatches.

“Looking at the same point on both [stress and resting images], it’s faster and easier to look at the subtraction images and enhance your confidence in the diagnosis,” Nelson said.

MIMvista’s approach also aligns with the trend of putting dedicated workstation capacity on a regular PACS workstation, with color monitors in this case.

The challenges of bringing nuclear medicine onto a PACS led Agfa to seek a partner for its solution. Dave Wilson, director of product management for Agfa, said his company partnered with Segami Corporation for its nuclear medicine PACS solution. He expects that it will be unveiled this fall.

Wilson pointed out that one challenge of bringing nuclear medicine to PACS is simply presenting images the way physicians are accustomed to seeing them. For example, nuclear medicine workstations vertically display a series of resting and stress images of the same location, and the physician examines the difference between the upper and lower image in each pair. Standard DICOM images would show a series of resting images and a separate series of stressed images—not the way the physician is accustomed to seeing them.

How to handle fusion imaging is another important issue, Wilson said. Combining a CT image with PET image into one DICOM image allows you to store it on a network, but to perform any postprocessing on the PACS network, you need both original images, which are created in two different formats. Putting such capability on a typical PACS station is a different challenge.

“Everyone wants to be able to store everything in one place and be able to access it from anywhere,” Nelson said. “The ability to have nuclear medicine capability brought into the PACS environment is going to make nuclear medicine more efficient.”

3. Developing your own. Some companies choose the homegrown route. For example, Reuven Shreiber, MD, vice president of clinical application for Algotech, a Kodak company based in Raanana, Israel, said Kodak is developing its software for handling nuclear medicine images on PACS. Building a system from scratch may be a slower process but fits with large companies’ desire to provide complete end-to-end solutions for customers, including making it easier to fully integrate with existing products. But that approach takes time and forces a PACS company to do things differently.

Facing the Challenge
“The whole PACS paradigm is based on the assumption that images are static, two-dimensional, and black and white. But for nuclear medicine, you have eight image types, four dimensions, motion, and color,” explained Xiaoyi Wang, president of Thinking Systems Corporation, in a 2004 Radiology Today article.

Thinking Systems specializes in working with nuclear medicine, PET, ultrasound, and catheterization lab images in a PACS environment. Unlike conventional PACS, its software was designed to work with colors and dynamic display. Those exact challenges led many PACS companies to solicit partners to build this capability. Thinking Systems’ software can function either as a stand-alone PACS for a facility or as a nuclear medicine add-on to an existing PACS.

“The difference between CT and MR and nuclear medicine is that nuclear medicine is four-dimensional—three dimensions in space and one dimension in time and has very low image resolution,” Wang said. “To overcome this and other challenges, vendors developed different proprietary technologies. The end result is that nobody can communicate with each other because each vendor has its own special format and the information that it needs. That has improved somewhat with DICOM, but you still have to use different protocols to acquire images for bone scans, for cardiac scans, for gallbladder scans, etc. Every organ has a different protocol, and it varies widely from vendor to vendor how images are acquired and processed. There is no place in DICOM for that kind of information.

“To develop a nuclear medicine PACS solution, you have to be able to handle all the proprietary information from all these different vendors,” Wang added. “We have special connectivity gateways to handle scanners that are not DICOM-compatible. We take the images in their native format, and we convert them into DICOM format, and we retain this proprietary information as private DICOM tags.

“You have to understand all major vendors’ special formats and preserve the proprietary information, and when you transfer images to other vendors’ systems, you will have to know how to convert the images from DICOM into the other vendors’ native formats,” said Wang. “The PACS also has to understand all the different processing protocols. You will have to be able to do the things a dedicated nuclear medicine workstation can do in the PACS environment—preprocessing, processing, postprocessing, and quantitative analysis.”

When Radiology Today first discussed this issue in 2004, people in the PACS industry field suggested that it would be two to three years until more options for handling nuclear medicine in a PACS environment hit the market. With one year remaining on that three-year prediction, more solutions—at least partial ones—are becoming available. Given that many facilities are still planning their initial conversion to PACS, facilitywide imaging networks handling nuclear medicine and all the other imaging modalities are a few years off in most locations, but more companies are working on the challenge.

— A Radiology Today staff report

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