Philips captures high ground in PET/CT with time-of-flight

Amid a stir created by competitors about high definition at the Society of Nuclear Medicine meeting, Philips Medical Systems quietly promoted what may be the ultimate answer to improved image quality: its proprietary time-of-flight PET/CT. Clinical data supporting the benefit of this approach are now being generated by the company's Gemini TF (TruFlight, commercially launched in 2006).

Philips' TOF technique measures differences in the time it takes photons created by the collisions, and consequent annihilations, of positrons and electrons to reach the detector, substantially increasing the precision with which radioisotopes can be localized.

"It uses the better localization of (annihilation) events to reduce noise and increase sensitivity, so the clinician can lower the dose and get better image quality with shorter scan times," said James K. Cavanaugh, director of global marketing for Philips nuclear medicine/PET.

Philips also reported clinical results from the University of Pennsylvania that TOF/PET produces remarkably improved images in shorter scan times. Researchers compared images from 30 patients using the standard acquisition time of 30 minutes against scan times as short as 10 minutes.

"TOF/PET imaging can achieve better quality images than conventional PET imaging in less time," said Amy Perkins, a Philips clinical site scientist at Penn.

The results also indicated that the benefit of TOF imaging is most significant for the heavy patient whose girth often requires extended scan times, typically greater than 30 minutes.

"This gives doctors the flexibility to improve patient comfort and increase the number of patients scanned without jeopardizing the ability to detect and quantify cancer," Perkins said. "In some cases, time-of-flight imaging detected lesions that were missed with conventional PET."

Cavanaugh noted that the company is pressing to improve image quality further with a pulmonary toolkit, introduced at the SNM meeting, to damp motion artifact from patient breathing. Gating the data collection process for PET and CT, reduces blurring in each data set and improves the clarity of the fused images. This translates into better lesion localization, particularly at the margins of lesions, which can be important in therapy planning, he said.

Also highlighted at the SNM meeting was the migration of Philips' NetForum approach, proven in MR and CT, to PET/CT. NetForum allows the sharing of protocols for scanning patients. Philips also recently implemented a remote service function that allows company service engineers to monitor installed systems for signs of trouble and head off problems before they occur.