Increased radiotracer uptake on positron emission tomography after invasive thoracic procedures: a case series

To investigate the hypothesis that tissue changes induced by invasive thoracic procedures may be associated with increased fluorine 18-labeled fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) scans, potentially leading to these tissue changes being mistaken for malignancies.

We retrospectively reviewed the records of all patients undergoing bronchoscopies and FDG-PET at Mayo Clinic Jacksonville from February 2002 to September 2004 and identified patients who had undergone computed tomography (CT) of the chest and bronchoscopy before FDG-PET. We identified and reviewed the imaging studies of patients who had increased FDG uptake on PET scans and whose CT scans showed no corresponding abnormalities suggestive of malignancy.

Eighty-one patients had undergone both bronchoscopy and PET within the defined study period. Of these, 45 (56%) underwent PET within 4 weeks after bronchoscopy, and 13 (29%) of these 45 patients had increased FDG uptake on PET scans that did not correlate with pathological findings on CT. We judged that increased uptake on 3 (23%) of the 13 PET scans was most likely related to the bronchoscopic procedure. Additionally, 2 patients who had undergone thoracoscopy after bronchoscopy but before PET had discordant CT and PET findings.

Invasive thoracic procedures may cause an increased uptake of radiotracer on PET scans that could be mistakenly interpreted as evidence of malignancy. To avoid clinical misjudgment, clinicians should perform PET before invasive thoracic procedures.