Data collection and review of PET/CT contribution
For each patient, we collected data on their demographics, medical history, current episode of fever, laboratory tests, and imaging studies. We examined the PET/CT results and reviewed the final diagnosis if it was made within 3 months of discharge. Finally, we evaluated the results of the PET/CT studies and concluded whether the test was contributory to the final diagnosis. This was determined by two internal medicine consultants. When controversies arose regarding the contributory value of a test, a third physician reviewed the data, and a decision was made based on the rule of the majority.
Tests were considered true positives and therefore contributory if they had positive findings that were relevant to the diagnosis. Studies were labelled as true negative if no positive hypermetabolic findings were observed, and no clinical diagnosis was established during 3 month follow-up. True negative tests (negative PET/CT scan, with no diagnosis made within 3 months) were not considered contributory since excluding diagnoses were not considered of value. Tests were called false positive if PET/CT showed hypermetabolic findings, but these findings did not add to the final diagnosis; or if no diagnosis was made at all within 3 months of follow-up. They were considered false negative if no hypermetabolic findings were observed and the diagnosis was made by other means of investigations.