Context and Policy Issues
Fluorodeoxyglucose-positron emission tomography (FDG-PET) is a nuclear medicine imaging technology whose use in the detection and evaluation of infections is an emerging indication. FDG-PET is currently used in the diagnosis and management of cancers, heart conditions, and neurological conditions.
Patient groups with infection that could potentially benefit from the use of FDG-PET include patients with skeletal or soft-tissue infections, immunosuppressed (HIV) patients, cancer patients, and patients requiring monitoring of therapeutic response. This technology could have important implications for disease management and patient outcomes if its use leads to earlier and more precise diagnosis, potentially preventing morbidity and mortality in a wide variety of conditions.
Because this technology may have wide application in infection, the potential addition to the current patient base could be significant. At the same time, the cost of operating this technology is relatively high compared with other diagnostic methods. A Canadian study estimated the average per-service costs to be between $1,231 and $7,869 (depending on annual throughput), and Alberta and British Columbia charge about $1,250 and $1,500, respectively, per scan for out-of-province residents.
There is no Canadian guidance on the use of FDG-PET in infections at the present time. The purpose of this report was to research and critically appraise the recent evidence on the effectiveness, safety, cost-effectiveness, and clinical impact of FDG-PET compared with other imaging methods in the diagnosis and management of infection, with the objective of informing guidance and policy on the use of FDG-PET for this indication.
- What is the evidence for the safety and clinical effectiveness of FDG-PET compared to other imaging techniques for the detection, characterization, or management of infections?
- What is the cost-effectiveness of FDG-PET compared to other imaging techniques for the detection, characterization, or management of infections?
- What is the evidence that FDG-PET alters or improves treatment of patients with infection?
Published literature was obtained by cross-searching Ovid’s MEDLINE and EMBASE databases. Web sites of regulatory agencies, and health technology assessment and related agencies, were also searched, as were specialized databases such as those of the University of York’s Centre for Reviews and Dissemination and The Cochrane Library (Issue 1, 2008). The Google™ search engine was used to search for a variety of information on the Internet.
Results include English language articles published between 2003 and March 2008 for systematic reviews and health technology assessments, and between 2005 and March 2008 for randomized controlled trials, observational studies, and economic evaluations.
The Centre for Evidence-Based Medicine (CEBM) tools for critical appraisal of systematic reviews and of diagnostic studies were used to evaluate the studies in this review.
Summary of Findings
Evidence identified for the clinical effectiveness of FDG-PET compared with other imaging techniques included two meta-analyses and seven prospective observational diagnostic studies. One retrospective observational study reported on the impact of FDG-PET in altering the treatment of patients with infection. Studies addressing safety issues and cost-effectiveness were not identified.
a) Evidence for Clinical Effectiveness of FDG-PET in Infections
For osteomyelitis, FDG-PET was suggested to be superior to several other imaging techniques in one meta-analysis, while less effective than MRI in one observational study, and useful only in the follow-up of patients in another observational study comparing it to single photon emission computed tomography (SPECT). Meta-analyses of FDG-PET in peripheric bone and prosthetic joint implants, and in infections of the vertebral column suggested superior accuracy of FDG-PET compared with other imaging methods. An observational study also found superiority of FDG-PET in detecting periprosthetic hip infection, compared with scintigraphy. FDG-PET was found to be superior to MRI in the differentiation of Charcot’s neuropathic arthropathy. Conclusions differed in two studies of FDG-PET in patients with multiple infection indications, with each study using different imaging methods as comparators.
A non-comparative retrospective study evaluated the use of FDG-PET in the diagnosis and management of invasive mould infections in 16 patients, and found this technology to be helpful in the clinical management of 10 (~60%).
b) Quality Assessment
The meta-analysis in osteomyelitis reported methodological shortcomings with the studies it included in its analysis. In addition, the meta-analysis of peripheric post-traumatic and prosthetic infection, and of infections of the vertebral column, had limitations with its methodology. A critical appraisal of the seven diagnostic observational studies included in this report indicated appropriate methods in the majority of attributes in most studies; however, there exists an overall potential bias in ascertaining the reference standard.
In spite of the wide range of potential indications for FDG-PET in infection and the numerous possible comparators, very few studies were retrieved within the parameters set for this review. There was no evidence on the safety of FDG-PET, and little evidence on this technology’s ability to affect treatment and outcome in patients with infections. Despite the relative cost of FDG-PET and its potential patient base, economic data were lacking.
Conclusions and Implications for Decision or Policy Making
Although suggestive of relative effectiveness in some indications, there is a lack of high-level evidence regarding the effectiveness of FDG-PET across indications and within a range of comparators. More intensive studies or systematic reviews and analyses of specific indications are needed, as well as evidence for this technology’s potential to alter patient treatment and outcomes. Assessments of cost-effectiveness and of the possible impact on resource allocation and wait times are also required.