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Positron emission tomography (PET) is effective in detecting sites of infection, particularly when metallic implants have been used to repair fractures, according to results of three studies presented at the 48th Annual Meeting of the Society of Nuclear Medicine in Toronto, Canada. The work was conducted in the U.S., Germany and Switzerland.
According to the American Academy of Orthopaedic Surgeons, more than 426,000
Americans will have joint replacement surgery; over 300,000 knee and hip replacements are performed each year. As Americans live longer, the likelihood they will undergo prosthetic replacement increases. However, infection and inflammation are potential complications of hip and knee replacement surgery.
Dr. Abass Alavi and associates at the Hospital of the University of Pennsylvania,
Philadelphia, evaluated PET’s ability to accurately diagnose bone and soft-tissue infections.
They analyzed the PET scans of 39 patients with chronic osteomyelitis, 87 patients with prosthesis-related infection and 10 patients with soft-tissue infection.
Infection was detected in 52 patients. The investigators found that PET had an overall accuracy rate of 91% in detecting sites of infection: its accuracy for detecting osteomyelitis and prosthesis-related infection was 93% and 92% respectively. Moreover, PET has greater
-more-

SNM: PET Detects Infections/Helps with Joint Replacements 2 capability for differentiating infection from surrounding bone marrow in cases of osteomyelitis when compared to white blood cell imaging, a technique commonly used to detect infection.
“PET is highly accurate imaging technique,” said lead study author, Dr. Alavi, “Because of its simplicity and high degree of accuracy, it has the potential to become a standard technique for the diagnosis of musculoskeletal infections.”
PET, a diagnostic imaging test that measures the body’s metabolic activity, has been used extensively in neurology and cancer studies. Research increasingly shows it also is particularly accurate in detecting infection in bones, joints and other body sites.
PET measures the body’s metabolic activity. A patient undergoing a PET scan is injected with the radiopharmaceutical fluorodeoxyglucose (FDG) about 45 minutes before the scan. The radiopharmaceutical tracer emits signals that are picked up by the PET scanner. A computer reassembles the signals into images that display the distribution of metabolic activity as an anatomic image. Areas that are more metabolically active show up more brightly on the scan.
PET’s clinical utility in detecting infection and monitoring therapeutic response was investigated by Dr. Thomas Kaelicke and associates at the University of Frankfurt in Germany.
They performed PET imaging prior to treatment on 21 patients with suspected osteomyelitis.
Subsequently, 15 patients underwent surgery; the PET imaging had shown bone infection in all
15. Follow-up laboratory studies confirmed the infection and the accuracy of the PET findings.
Moreover, PET clearly distinguished between bone infection and soft-tissue infection surrounding the bone. For two patients who participated in a follow-up study, PET accurately assessed therapeutic response: normal or reduced tracer activity on the scan demonstrating no infection was corroborated by laboratory data.
“PET offers another diagnostic tool for infection imaging,” said Dr. Kaelicke, “and unlike conventional imaging tests such as computed tomography or MRI, PET image quality is not affected by the metal implants used to fix fractures.”
At the University Hospital Zurich in Switzerland, Dr. Katrin Stumpe and colleagues found that PET was effective in detecting infection in 22 patients with metallic implants. The metallic material used in the implants had no negative impact on the PET scans. The investigators also found that PET’s high resolution could clearly distinguish between bone and soft-tissue infections.

SNM: PET Detects Infections/Helps with Joint Replacements 3
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The Society of Nuclear Medicine is an international scientific and professional organization of more than
13,000 members dedicated to promoting the science, technology, and practical application of nuclear medicine.
SNM is based in Reston, Virginia. For more information, visit the SNM website at www.snm.org.
All presented Sunday, June 24, 4:15 - 5:45 p.m. Room 716 B
Abstract 161
FDG-PET for the Diagnosis of Infections
B. Moussavian, H.M. Zhuang, F. Ponzo, M.A. Christians, A. Alavi, Hospital of the University of
Pennsylvania, Philadelphia
Tel: 215-662-3069 Fax : 215-349-5843 alavi@oasis.rad.upenn.edu.
Abstract 162
Infection Detection with FDG PET in Patients with Metallic Implants
K.D. Stumpe, Nuclear medicine, Zuerich, Switzerland; M. Schlesser, T. Kossmann, Department of
Surgery, Zuerich Switzerland; G.K. von Schulthess, Nuclear Medicine, Zuerich, Switzerland
Tel: 0041 1 255 3555 Fax: 0041 1 255 4414 Katrin.stumpe@dmr.usz.ch
Abstract 163
FDG PET in Diagnosis and Follow-up of Bone Infections
T. Kaelicke, BG Kliniken Bergmannsheil, Bochum Germany; J.H. Risse Department of Nuclear
Medicine, University Frankfurt, Frankfurt German; A. Schmitz, O Schmitt, Department of
Orthopaedics, University Bonn, Bonn Germany; S. Arens BG Kliniken Bergmannsheil, Bochum
Germany; H.J. Biersck, Department of Nuclear Medicine, University Bonn, Bonn Germany; F.
Grunwald, Department of Nuclear Medicine, University Frankfurt, Frankfurt, Germany
Tel: 49 234 30 20 Fax: 49 234 302 65 30 Kaelicke@aol.com