Single-photon emission computerized tomography (SPECT/CT) systems are a key tool to diagnose and monitor diseases, but for the past sixty years the technology has remained more or less the same. This year, the Israeli R&D center of GE Healthcare developed a new system that overcomes many of the problems of the systems that are largely in use at hospitals around the world.
“We believe that the new technology in the Discovery NM/CT 670 CZT system will significantly improve the way exams are performed and enable new areas of exploration for researchers who are looking at ways to optimize imaging protocols and gain additional insights about a patient’s condition,” said Nathan Hermony, general manager of Nuclear Medicine at GE Healthcare.
“This the first reboot for the camera technology used in SPECT/CT imaging in decades, and it was developed at our facilities in Rehovot and Haifa. We have about 600 employees between the two facilities.”
SPECT scans, especially when merged with CT scans (while the two images are usually generated by separate machines, SPECT/CT systems can present a single image) produce 3D images of organs in action. For example, SPECT images can show what parts of the brain are active, which areas of the lungs have trouble absorbing oxygen, etc. CT scans, meanwhile, provide a cross-section of organs, bones, blood vessels and soft tissues. The images are used to analyze a variety of medical issues, such as clogged arteries, heart failure, seizures and endemic headaches.
Patients are injected with a radioactive substance which acts as a tracer for the camera in the SPECT/CT machine. The system is usually built as a large circular device, with the patient lying down on a bed and the machine rotating around them and taking images of the areas where the radioactive substance was injected.
Because of the limited scope of the cameras used until now, doctors could only get one image at a time; if there was a need to examine the hearts, lungs, and kidneys, three passes had to be made, and patients had to be injected with tracer material three times. While generally regarded as safe, it’s probably not a good idea to inject an ailing patient with anything too many times, much less a radioactive substance, said Hermony.
The GE system was developed using CZT (cadmium zinc telluride) technology. CZT is a unique semiconductor that directly converts x-ray or gamma-ray photons into electrons, and is able to process many more photons than the current cameras.
Because they are more accurate and much more compact CZT detectors can be placed very tightly in an array, allowing for the imaging of more than one part of the body at a time. Moreover, the additional imaging power means that much less radioactive tracers are needed – as much as 50% less, said Hermony.
With the system, patients who may have had to undergo multiple scans in the past – with the accompanying hassle of having to contort their limbs in order to get into the right position for each scan – can get all their scanning done in one pass, said Hermony.
“One example is cardiac SPECT exams that require the patient to hold their arms above their shoulders for the entire exam, very tightly to the head in order to permit the detectors to rotate closely around the chest for the best image quality,” he said. “For patients with arm or shoulder pain this can be extremely painful and possibly intolerable for the duration of the scan. The new SPECT/CT technology comes with tightly packed detectors, which allow increased proximity and flexibility when positioning the patient for the exam; therefore patients are not required to hold still in strenuous positions and they can tolerate the exam better.”
Hospitals will benefit as well, said Professor Zohar Keidar of Rambam Hospital, where GE is placing one of its systems. “The use of this technology may also result in an increased patient throughput and lower procedure-related costs. We are thrilled about the opportunity to be currently involved in investigating and defining the optimization of the clinical protocols based on the use of this novel technology and are also looking forward to exploring new exciting research avenues in the very near future.”