FDG PET takes its place as a valuable tool in diagnosing fevers of unknown origin

Study widens use of PET scans, say researchers in the Netherlands; Report issued at SNM's 53rd Annual Meeting June 3–7 in San Diego

SAN DIEGO, Calif.--By providing early diagnosis of fevers of unknown origin in patients, positron emission tomography (PET)--with the radiotracer fluorodeoxyglucose (FDG)--eliminates the need for additional exhaustive and invasive tests, say researchers from university and community hospitals in the Netherlands. Their findings were presented during SNM's 53rd Annual Meeting June 3–7 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 health care 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.

PET is a safe, effective and painless biological imaging exam that uses very small amounts of radioactive material targeted to specific organs, bones or tissues. Radiotracers (such as FDG) are injected and then detected by a special type of camera that works with computers to provide precise pictures of the area of the body being imaged and molecular images of the body's biological functions. FDG accumulates where there's abnormal and uncontrolled cell growth and activated inflammatory cells, said Oyen, thus making it a valuable diagnostic tool. FDG-PET scans are traditionally used with cancer patients, said Oyen. "We studied a relatively new application of PET that could broaden its use," he added.

"This research highlights the important potential contribution of PET especially in the areas of fevers of unknown origin and infection," noted Bruce Line, SNM's Scientific Program Committee general clinical specialties vice chair. "Patients are well served with a study that could eliminate them from continued exhaustive workups," added the professor of radiology and director of the division of nuclear medicine at the University of Maryland, College Park, Md.

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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.

About SNM

SNM is holding its 53rd Annual Meeting June 3–7 at the San Diego Convention Center. Research topics for the 2006 meeting include molecular imaging in clinical practice in the fight against cancer; the role of diagnostic imaging in the management of metastatic bone disease; metabolic imaging for heart disease; neuroendocrine and brain imaging; new agents for imaging infection and inflammation; and an examination of dementia, neurodegeneration, movement disorders and thyroid cancer.

SNM is an international scientific and professional organization of more than 16,000 members dedicated to promoting the science, technology and practical applications of molecular and nuclear imaging to diagnose, manage and treat diseases in women, men and children. Founded more than 50 years ago, SNM continues to provide essential resources for health care practitioners and patients; publish the most prominent peer-reviewed resource in the field; sponsor research grants, fellowships and awards; host the premier annual meeting for medical imaging; and train physicians, technologists, scientists, physicists, chemists and radiopharmacists in state-of-the-art imaging procedures and advances. SNM members have introduced--and continue to explore--biological and technological innovations in medicine that noninvasively investigate the molecular basis of diseases, benefiting countless generations of patients. SNM is based in Reston, Va.; additional information can be found online at http://www.snm.org.


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