July 2010

Technology Update: PET
Radiology Today
Vol. 11 No. 7 P. 18

For a nuclear medicine imaging modality as sophisticated as PET and PET/CT, new products and enhancements to existing systems come from customer feedback on everything from functionality to image quality, and the need for cost-effective imaging solutions.

GE Healthcare Americas
Adaptive Statistical Iterative Reconstruction: Reducing Noise and Dose
GE Healthcare has added to its Discovery PET/CT 600 series platform with the introduction of dual-detector capabilities and an enhanced application suite available in the Discovery PET/CT 690 with BrightSpeed Elite CT. The Discovery PET/CT 600 system can be configured with the Discovery PET/CT 690 detector, providing flexibility to assist in clinical implementations and imaging exploration.

“The Discovery platform was introduced nearly two years ago and we have continued to develop functionality upon that since that time,” says Lynn Bender, global marketing manager for PET/CT, part of the molecular imaging unit of GE Healthcare.

The BrightSpeed Elite CT provides advanced imaging capabilities and allows for reduced doses by utilizing Adaptive Statistical Iterative Reconstruction (ASIR). The ASIR technology extracts noise by synthesizing new projections and then statistically compares them with original projections. It then iteratively corrects the raw data until the image quality criteria is satisfactory. ASIR maps and corrects the unwanted noise, which reduces the required dose for high-quality imaging.

“We’re able to reduce the CT dose by up to 40% without compromising image quality,” Bender says.

With a focus on contrast and resolution, another addition to the Discovery PET/CT 600 series is SharpIR. This is an iterative reconstruction technology with advanced system modeling designed to enhance visual contrast and resolution in both whole-body and brain PET images.

From a workflow perspective, an improved IBM Blade Center VUE Point FX completes image reconstruction twice as fast as before, reducing a patient’s scan time to less than 75 seconds per bed position. Scans can be reviewed while patients remain on the table. In addition, a new 2-meter scan option allows for head-to-toe exams in one scan.

“For full-body scans, such as those necessary for bone or skin imaging, this allows clinicians to complete the scan without having to flip patients during the process,” she says.

The company has also launched InSite OnWatch for PET/CT, a technology that uses data-driven prediction tools to monitor Discovery PET/CT 600 series systems, identify impending failures, and forecast maintenance needs.

“This allows for more proactive system maintenance,” Bender says. “If we see a problem, we can notify the customer and either remotely fix it or proactively send a repair person to the client site. This can help reduce down time for our customers.”

Naviscan, Inc
New PEM-Guided Biopsy Accessory
Naviscan’s breast-specific positron emission mammography (PEM) scanners were recently part of a National Institutes of Health-sponsored, multisite study that found PEM was more precise in differentiating between benign and cancerous lesions, therefore potentially reducing the number of unnecessary biopsies. In the study, which compared PEM and MRI for secondary disease, PEM demonstrated 26% higher positive predictive value than breast MRI and comparably high sensitivity. In addition, PEM demonstrated a 6% improvement in specificity at comparably high sensitivity.

“The results of this study mean that not only do physicians have an additional tool to help treat breast cancer, but that PEM is a legitimate alternative for women who cannot tolerate MRI due to claustrophobia or other medical reasons,” says Guillaume Bailliard, vice president of marketing for Naviscan.

The study involved 388 women who had just been diagnosed with breast cancer. The results, which were published in January, reviewed the reasons high-risk women who were recommended for breast MRI screening refused to undergo the exam.

A new feature for Naviscan is the addition of Stereo Navigator, a PEM-guided biopsy accessory.

“PEM is essentially a high-resolution breast-specific PET scanner that can show the location as well as the metabolic phase of a lesion,” Bailliard says. “Imaging modalities such as mammography and ultrasound show only the location. For the first time in PET imaging, we can now biopsy with PET guidance only.”

 Stereo Navigator uses a stereotactic frame fixed between the scanner’s paddles to guide the insertion of a compatible interventional device into the breast. The system acquires high-resolution 3D tomographic images and the location of any abnormality is verified using a PET-visible line source that is inserted into the needle track that allows users to confirm trajectory and position.

Philips Healthcare
Targeting Cost-Effective Performance
Philips aimed to provide customers with cost-effective, high-performance technology with the launch of its GEMINI LXL PET/CT scanner. This device incorporates a LYSO crystal and other detector technologies that improve image quality and result in faster scan times. The sensitivity and extended field of view offer the image quality necessary for PET applications in oncology, neurology, and cardiology.

“This is our response to a changing economy,” says Scott Smith, senior product manager for PET/CT with Philips Healthcare. “Our customers have limited budgets, but they’re not willing to compromise on image quality. The GEMINI LXL provides premier imaging at an affordable cost.” Smith says the GEMINI LXL system is scheduled to ship in the second quarter of 2010.

Additional features include Philips’ patented OpenView gantry design, a 190-cm scan length for both PET and CT that allows for true whole-body scans and the Brilliance CT 16-slice configuration.

In other developments, Philips integrated its GEMINI TF PET and Brilliance CT Big Bore to assist in cancer staging as well as meet the workflow challenges and performance and connectivity requirements of radiation oncology.

“This development extends PET/CT into radiotherapy treatment planning,” Smith says, “making this a viable option for patient staging, treatment planning, and follow-up. Radiation oncology facilities could use this for treatment planning and nuclear medicine could see use in cancer staging as well as cardiac imaging.”

Philips’ TruFlight time-of-flight PET technology, now in its third generation, is designed specifically for use in radiation oncology. It allows for high-resolution, diagnostic whole-body PET scans quickly yet with extreme sensitivity, allowing for low doses.

Philips expanded its Extended Brilliance Workspace Nuclear Medicine to add a new tumor tracking application. This application uses sequential PET/CT scans to assist in monitoring tumor progression and any potential response to ongoing therapy. Clinicians can measure changes in tumor size and metabolic activity by comparing up to six sequential PET/CT studies at one time.

On the research front, Philips is working in a clinical collaboration agreement with Hospital University of Geneva in Switzerland and Mount Sinai School of Medicine in New York in the area of whole-body PET/MRI development. The combination of the two modalities had been a problem because the magnetic field created major artifacts in the PET acquisition. Philips Healthcare is researching a solution to this problem by providing a combined PET/MRI scanner with integrated patient handling for whole-body imaging. Both research centers are equipped with a Philips 3T MR and PET using time-of-flight technology.

“This research project brings together the best of soft tissue scanning and the best functional scanning for a future imaging modality,” Smith says.

Siemens Medical Solutions, USA
Siemens looks to make detecting even the smallest lesions more likely with its HD-PET offering. According to Siemens, HD-PET provides twice the signal-to-noise improvement over conventional PET and near-uniform spatial resolution of 2 mm throughout the entire field of view, with clearer, more defined images from edge to edge, regardless of a patient’s body type.

“HD-PET images show uniform resolution across the entire view, not just the center,” says Robert Brait, national product manager for Siemens’ PET/CT molecular imaging division.

The HD-PET technology is fully compatible with Siemens’ Biograph TruePoint family of PET/CT scanners and can be incorporated as an upgrade to that system. In addition, Siemens’ dynamic PET plays a significant role in cardiac care, allowing clinicians to calculate coronary flow reserve.

“A patient could come in with an occlusion in each of three coronary vessels,” Brait says. “The patient looks normal but is experiencing symptoms of cardiac distress. With our PET, you can calculate the flow of blood through all three vessels, then see a profused view and detect the triple-vessel distress. This allows you to better manage the patient.”

In an effort to simplify access to information, Siemens is launching a thin-client server that will enable clients to access images from any location. Rather than storing data on individual workstations, the information will be housed on a centrally located server that can easily be accessed remotely. The thin-client setup allows Siemens to provide updates through the server rather than to one workstation at a time.

Overall, Siemens’ Biograph products for PET/CT are designed to be easily upgraded as new advancements are released. Both the TruePoint and mCT platforms are designed for incremental upgrades, Brait says.

Looking to the future, Brait says Siemens is designing PET and PET/CT product and software developments to be more patient specific, focusing on reducing scan times and radiation doses without compromising image quality.