PET/CT Could Be Useful Tool in Evaluating Unexplained Fever

Fevers with an unexplained origin could be effectively evaluated with 18F-FDG PET/CT, new research has revealed.

In a study published recently online in Clinical Infectious Diseases, a team of investigators from Johns Hopkins University discussed how using PET/CT can lead to faster diagnosis, as well as more accurate care delivery.

“The presence of abnormal [¹⁸F-FDG] uptake can help direct further investigation that may yield a final diagnosis,” wrote the team led by William W. Wright, D.O., MPH, an infectious disease expert. “A lack of abnormal uptake can be reasonably reassuring that these conditions are not present, thereby avoiding unnecessary additional testing.”

The team identified a patient as having a fever of unknown origin if he or she had an unexplained fever for three outpatient visits or for three days in the hospital, and they put fevers into five categories: infections, cancers, non-infectious inflammatory disorders, miscellaneous other disorders, and undiagnosed illness. Assessing these fevers, the team added, frequently requires laboratory tests and imaging.

Currently, the Centers for Medicare and Medicaid Services does not provide coverage for outpatient PET/CT scans conducted for unexplained fever. However, the team explained, there is an existing body of literature that points to the potential of these scans to augment diagnostic accuracy and reduce costs in the long term.

These studies, they pointed out, recommend using ¹⁸F-FDG PET, mostly in conjunction with CT imaging, when doctors either do not have enough information or have misleading clues about a patient’s condition. But, it is frequently seen as the option of last resort, leading to a forced hospitalization to obtain the study. Doing so adds costs to the healthcare system, they said.

“We propose that [the exam] has value placed earlier in the diagnostic strategy despite potentially prompting invasive testing,” the team said.

To determine how effective PET/CT is in evaluating unexplained fever, Wright’s team completed a literature review of four studies. Based on their analysis, they identified an overall sensitivity of 97.9 percent with an over-arching agreement of 78.9 percent with other diagnostic techniques.

Consequently, the team determined ¹⁸F-FDG PET/CT can be a beneficial and helpful tool when other tests and studies are “unrevealing.” Using it could also truncate the time needed for evaluation and provide cost savings.

“Reducing unnecessary, invasive, and expensive diagnostic investigations, achieveing an earlier final diagnosis, and reducing the number of undiagnosed cases are how [¹⁸F-FDG PET/CT] may limit the cost of fevers of unknown origin evaluations,” the team said.