Firm’s functional anatomic mapping system is highlight GE Medical Systems pulled off the corporate equivalent of a slam dunk at this month’s Society of Nuclear Medicine meeting in Los Angeles. The Milwaukee company packed crowds
Firms functional anatomic mapping system is highlight
GE Medical Systems pulled off the corporate equivalent of a slam dunk at this months Society of Nuclear Medicine meeting in Los Angeles. The Milwaukee company packed crowds into its SNM booth with the debut of a new technology that adds an x-ray tomographic capability to a gamma camera, thus merging the anatomic detail of x-ray studies with the functional capabilities of nuclear medicine.
GE calls the new technology functional anatomic mapping, and it is designed to rectify a long-standing problem in nuclear medicine: the low spatial resolution of nuclear medicine studies. While nuclear medicine provides information on the bodys functional processes available with few other modalities, the fuzzy images produced by gamma cameras often include only blurry outlines of anatomical structures. This can make it difficult to accurately localize the lesions that appear as hot spots on nuclear medicine images.
Vendors and nuclear medicine physicians have tried to compensate for nuclear medicines low spatial resolution by developing image fusion protocols that use software to merge nuclear medicine studies with images collected by anatomical modalities. But these protocols often have their own problems: they call for two separate scanners, and require a significant amount of work to ensure that the different images are registered to each other properly.
Functional anatomic mapping represents GEs effort at resolving the dilemma. The technique takes a low-dose x-ray tube and CT-style solid-state detector array and grafts them onto the gantry of the companys Millennium VG variable-angle dual-head gamma camera. The technique is well-suited for Millennium VG because the cameras slip-ring design means that it can rotate continuously around the patient, an important benefit for tomographic studies.
During a functional anatomic mapping study, the x-ray assembly produces digital tomographic data of the patients anatomy, collected either before or after the radiopharmaceutical study is conducted. The data are then fused with software algorithms and displayed as a single image on a workstation. Conducting a functional anatomic mapping exam adds about nine minutes to a study, and the patient doesnt need to be moved off the cameras patient bed. The assembly does not interfere with the ability to adjust Millennium VGs detector heads, such as into the 90° position for cardiac studies.
At a press conference announcing the technology, GE executives and nuclear medicine luminaries in attendance were careful to point out that functional anatomic mapping is not intended for diagnostic applications. Instead, it is designed to provide a rough anatomic map that physicians can use to more accurately pinpoint the location of radiopharmaceutical uptake. Functional anatomic mapping can also be used for attenuation correction applications, according to Beth Klein, general manager of GEs global nuclear medicine/PET unit. The technique represents a big improvement on the attenuation correction protocols now in use, which employ radioactive sources externally mounted on gamma cameras, she said.
Millennium VG gamma cameras with functional anatomic mapping have been installed at Vanderbilt University in Nashville, TN, Duke University in Durham, NC, and Rambam Medical Center in Israel. At Vanderbilt, researchers have found the anatomical information collected by the technique useful in both localizing and staging tumors, particularly when used with FDG, according to Dr. Martin Sandler, professor of radiology and medicine at Vanderbilt.
This clearly brings us to a crossroads in nuclear medicine, Sandler said. We have been working just on coincidence imaging, but (FAMs) ability to provide anatomical mapping for all types of nuclear medicine studies will improve both the accuracy and the diagnostic performance of the technology.
Functional anatomic mapping was developed at ELGEMS, the Israeli company formed as a joint venture between Elscint and GE in 1997. ELGEMS now serves as GEs center of excellence for nuclear medicine R&D. ELGEMS began working on functional anatomic mapping soon after the joint venture was founded, according to Nathan Hermony, president and CEO of the company.
Functional anatomic mapping will be available as an option for new Millennium VG cameras, and can be added to Millennium VG systems in the field. It is also adaptable to VariCam units installed by Elscint before GE acquired that company last year (GE renamed VariCam Millennium VG following the formation of ELGEMS). GE has applied for 510(k) clearance for the technique.
A sign of progress. The introduction of functional anatomic mapping highlights how far GE has progressed in nuclear medicine in the last two years. Through the mid-1990s, the company trailed its competitors due to its lackluster product line, which stood in sharp contrast to the vendors reputation for technological leadership in other modalities. Indeed, some industry observers posited that the companys nuclear division suffered as GE funneled R&D funds into more glamorous modalities.
GE began to turn the nuclear medicine business around in 1997. First it signed a technology development deal with Elscint that resulted in the formation of ELGEMS (SCAN 6/25/97). GE then proved that it was willing to spend money in the modality by acquiring Elscints nuclear medicine business (SCAN 12/16/98). The moves have paid off: At this years SNM conference, functional anatomic mapping was one of the few new technologies on display on the exhibit floor, at last giving GE the opportunity to claim the mantle of nuclear medicine innovator.
Rivaling GE for the attention of SNM attendees was Siemens Medical Systems, which generated interest with images collected by a combination CT/PET scanner developed by CTI PET Systems, the PET joint venture between Siemens and CTI of Knoxville, TN (SCAN 6/24/98). Although the hybrid camera is at present more of a research project than a commercial product, Siemens prevented GE from totally dominating the conference when Dr. Henry Wagner of Johns Hopkins in Baltimore named a Siemens CT/PET image as Image of the Year in his post-SNM roundup speech.
Both the Siemens combination scanner and GEs functional anatomic mapping technique are hybrid technologies, but differ in important ways. The x-ray maps generated by functional anatomic mapping are not intended for diagnostic applications. Siemens, however, believes that clinicians pursuing hybrid imaging in the future may prefer to have the best possible diagnostic quality images. That would call for a combination of PET and CT rather than a hybrid gamma camera/x-ray tomography unit, according to Paul Ottoson, marketing manager for the companys nuclear medicine group in Hoffman Estates, IL.
Nuclear medicine physicians would have to pay a price for the higher quality, however, as the Siemens hybrid scanner would carry a far higher price tag than a Millennium VG camera with a functional anatomic mapping upgrade. Siemens has yet to decide whether to bring the combination scanner to market as a commercial product.
Regardless of the differences, both technologies represent encouraging first steps toward the development of hybrid scanners that meld the best traits of different modalities. In the long run, vendors will be able to bring down the cost and improve the diagnostic quality of these systems, to the ultimate benefit of patient care.
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