FDG PET a tool in diagnosing mysterious fevers

By providing early diagnosis of fevers of unknown origin in patients, positron emission tomography used with fluorodeoxyglucose (FDG) eliminates the need for additional exhaustive and invasive tests, say researchers from university and community hospitals in the Netherlands. The findings were presented Monday during SNM’s 53rd Annual Meeting in San Diego.

“PET has the potential to make an enormous impact in providing earlier diagnosis and risk stratification, in delivering the right therapy early and in avoiding long in-patient hospital stays,” said Wim J.G. Oyen, nuclear medicine physician and professor of nuclear medicine at Radboud University Nijmegen Medical Centre in Nijmegen, the Netherlands. “For patients with fever of unknown origin, FDG PET offers the chance for earlier diagnosis with fewer diagnostic procedures and an earlier start of adequate treatment. For referring physicians, FDG PET offers the opportunity to shorten the diagnostic process, which is now often performed during a long in-patient evaluation—in many cases over many weeks,” added the co-author of “A Prospective Multicenter Study of the Value of FDG PET as Part of a Structured Diagnostic Protocol in Patients With Fever of Unknown Origin.”

When an individual’s temperature reaches 101 degrees Fahrenheit on and off for at least three weeks and healthcare providers cannot diagnose the cause, the patient is considered to have a fever of unknown origin. Research suggests that fever helps fight off infections, and treating the fever without knowing the cause may reduce the body’s ability to deal with the possible infection. So patients undergo numerous tests to narrow down the possible causes, such as infections (tuberculosis, mononucleosis, HIV, pneumonia, meningitis), cancer (leukemia, Hodgkin’s disease) or collagen vascular disease (rheumatoid arthritis). In some cases, the tests fail to explain the reason for the fever, said Oyen. “Fevers of unknown origin, which may be caused by any one of more than 200 disorders, are a major diagnostic challenge,” he noted.

“We were struck by the fact that PET indicated that half of the 70 patients studied had no abnormal findings as the cause of the fever,” said Oyen. With a negative result from a PET scan, physicians “can cross out other diagnostic tests (such as chest X-rays and abdominal ultrasound) since those tests won’t reveal causes for the fever,” he said. In addition, PET contributed to the diagnosis of one-third of the patients, “picking up diseases that would have required other diagnostic tests,” he noted. “Such an earlier diagnosis saves time since PET leads to intelligent further testing, not a buckshot approach,” he added.

Abstract: C.P. Bleeker-Rovers, L.F. de Geus-Oei, F.H. Corstens, W.J. Oyen, all nuclear medicine, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands; F.J. Vos and J.W. van der Meer, internal medicine, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands; A.H. Mudde, internal medicine, Slingeland Hospital, Doetinchem, Netherlands; A.S. Dofferhoff, internal medicine, Canisius-Wilhelmina Hospital, Nijmegen, Netherlands; A.J. Rijnders, nuclear medicine, Rijnstate Hospital, Arnhem, Netherlands; P.F. Krabbe, MTA, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands, “A Prospective Multi-Center Study of the Value of FDG PET as Part of a Structured Diagnostic Protocol in Patients With Fever of Unknown Origin,” SNM’s 53rd Annual Meeting, June 3–7, 2006, Scientific Paper 40.