Infection imaging using whole-body FDG-PET

The purpose of this study was to evaluate fluorine-18 fluorodeoxyglucose po sitron emission tomography (FDG-PET) for the detection of soft tissue and b one infections. Forty-five PET examinations in 39 patients (26 male, 13 fem ale, age range 27-86 years) with suspected infectious foci were examined wi th whole- or partial-body PET scans using FDG. Twenty-seven scans were done in patients with soft tissue and 18 in patients with bone infections. Corr ected and uncorrected transaxial PET images were acquired. Seven hundred an d twelve body regions in these 45 PET scans were evaluated. Pathological fi ndings were graded using a confidence scale from A to E (A, definitive infe ction; E, no infection). Disease status was defined in all patients by cult ure, biopsy or surgery and clinical follow-up. In 45 PET scans there were 4 0 true-positive, four false-positive and one false-negative findings. Twelv e foci suspected to be infectious in nature on the basis of other imaging e xaminations were identified as negative by PET, thus representing true-nega tive findings. Sensitivities for the patients with soft tissue (STI) and bo ne infections (BI) and for the pooled data were 96%, 100% and 98%, respecti vely. As the calculation of specificity is not straightforward, it was calc ulated on a per lesion as well as on a per body region basis to permit esti mation of an upper and a lower limit. On a per lesion basis, specificities were 70% (STI), 83% (BI) and 75% for the pooled data and on a per body regi on basis (dividing the body into 22 regions) they were 99% (STI), 99% (BI) and 99% for the pooled data. One false-negative result was found in a patie nt with cholangitis. It is concluded that PET appears to be a highly sensit ive method to detect infectious foci. Specificity is more difficult to esti mate, but is probably in the range from 70% to above 90%.