Abstract 4367053: ¹⁸ F-FDG PET/CT Evaluation of Incidental Extracardiac CT Findings on ⁸² Rb-Chloride PET Myocardial Perfusion Imaging

Background: Positron emission tomography (PET) combined with computed tomography (CT) is a valuable strategy for myocardial perfusion imaging (MPI) in ischemic heart disease evaluation. CT attenuation correction (CTAC) enhances the diagnostic performance of PET and provides further characterization of the coronary vasculature. CTAC performed as part of MPI, however, frequently reveals incidental extracardiac findings whose clinical significance remains underexplored. Research Question: This study aimed to assess the prevalence of incidental extracardiac lesions on 82 Rb-chloride PET/CT MPI and investigate whether subsequent 18 F-FDG (fluorodeoxyglucose) uptake patterns identify clinically actionable lesions, particularly those suggesting occult malignancy. Methods: This retrospective study included 468 patients from the West Los Angeles Veterans Affairs Medical Center who underwent 18 F-FDG PET/CT within six months of 82 Rb-chloride PET/CT MPI between January 2017 and July 2022. From this cohort, 162 patients who underwent 82 Rb-chloride PET/CT MPI first and had no prior malignancy history were identified as the target cohort. Positive predictive values and chi-squared analyses evaluated the association between extracardiac lesions identified on CTAC and subsequent 18 F-FDG uptake. Results: A total of 209 extracardiac findings were noted on CTAC in the target cohort, with 108 demonstrating positive 18 F-FDG uptake. Pulmonary nodules were the most commonly identified extracardiac finding on CTAC and comprised 30% of all incidental lesions. Pulmonary nodule size was significantly associated with 18 F-FDG uptake, particularly in smokers (chi-squared value = 26.4, P < 0.001). In non-smokers, while isolated pulmonary nodules had no association with 18 F-FDG uptake, those accompanied by lymphadenopathy exhibited a trend towards significant association with 18 F-FDG uptake (chi-squared value = 10.9, P = 0.052). Conclusions: Extracardiac findings observed on CTAC during 82 Rb-chloride PET MPI in patients without a history of cancer are associated with subsequent 18 F-FDG uptake on PET/CT. This association is influenced by pulmonary nodule size, with a stronger relationship observed in patients with a history of smoking. These findings underscore the importance of integrating extracardiac lesion evaluation with patient demographics into routine cardiovascular imaging workflows to identify patients at highest risk for indolent malignancy.