Report from SNM: FDG-PET proves worth for infection detection

FDG-PET can answer clinically relevant questions about the presence of infection associated with prosthetic knee joints, according to a University of Pennsylvania study presented at the 2009 SNM meeting.

Professor of radiology Dr. Abass Alavi and colleagues at Penn evaluated 80 patients with painful symptoms experienced not long after knee joint replacement surgery. Fifty underwent clinical and laboratory exams in addition to FDG-PET imaging and full follow-up.

Although the clinical and lab data were inconclusive, FDG-PET accurately identified eight of nine patients with infections associated with their prosthetic knee implants. It also confirmed the absence of infection in 38 of 41 cases.

More than one million joint replacements are performed in the U.S. each year. Though infection is common after joint replacement surgery, it is hard to distinguish from other complications. In many cases, additional surgery to remove the prosthetic joint is necessary, but physicians often decide to take this route based on faulty information, Alavi said.

Radiolabeled white-cell imaging, the standard technique, accurately diagnoses infections in only about half of the patients. It is also a labor-intensive, time-consuming, and expensive approach, Alavi said. FDG-PET is not only more accurate and cost-effective to perform than white-cell imaging, but it can diagnose infection with minimal suffering for these patients. It could eventually be used to detect inflammation as well.

"The mother of all the diseases is inflammation, and there is no other technique better than FDG-PET right now for this purpose," he said.

Alavi pointed out that patients with fevers of unknown origin have been successfully diagnosed using FDG. With a single test, physicians can spot the site of infection or an abscess and discharge patients the next day, whereas the standard procedure may mean a long hospital stay, which is bad for patients and healthcare as a whole, he said.

"I've been saying for the past 30 years that the future of nuclear medicine and the future even of modern imaging is going to be with PET," Alavi told Diagnostic Imaging. "And the sooner we get into this, the better off we are."