Nucl Med Commun 2002 Sep;23(9):851-5
The importance of the location of fluorodeoxyglucose uptake in periprosthetic
infection in painful hip prostheses.
Chacko TK, Zhuang H, Stevenson K, Moussavian B, Alavi A.
Ten per cent of patients with hip replacement will eventually complain of
significant pain after surgery, often requiring a revision arthroplasty. The
majority of these patients experience aseptic loosening rather than infection.
Despite significant advances made in diagnostic imaging, distinguishing
infection from aseptic loosening remains a significant challenge. Imaging using
fluorodeoxyglucose (FDG) positron emission tomography (PET) has been reported to
have excellent sensitivity in detecting infections associated with hip
prostheses. However, in some studies, a high rate of false positive results has
been reported, especially when increased tracer uptake adjacent to the
prosthesis (which is not surrounded by bone) is used as the sole criterion for
diagnosing infection. The objective of this investigation was to determine the
optimal criteria for diagnosing periprosthetic infection, thereby avoiding false
positive results in this setting. A total of 41 total hip arthroplasties from 32
patients and for whom complete clinical follow-up was available were included in
this analysis. The location and intensity of FDG uptake were determined for each
scan. Final diagnosis was made by microbiology, histopathology, surgical
findings and clinical follow-up. Patients who did not undergo surgery were
followed up to at least 9 months. Twelve patients were proven eventually to have
periprosthetic infection. Images from 11 of these patients displayed increased
tracer uptake along the interface between bone and prosthesis. The intensity of
the increased tracer uptake varied from mild to moderate, with standardized
uptake values less than 2. In contrast, images from uninfected, loose hip
prostheses revealed very intense uptake around the head or neck of the
prosthesis with standardized uptake values as high as 7. It is concluded that
the intensity of increased FDG uptake is less important than the location of
increased FDG uptake when FDG PET is used to diagnose periprosthetic infection
in patients with hip arthroplasty. Using increased uptake as the sole criterion
for diagnosing infection will result in false positive results in this setting.
