Abstract Body (Do not enter title and authors here): 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 ⁸²Rb-chloride PET/CT MPI and investigate whether subsequent ¹⁸F-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 ¹⁸F-FDG PET/CT within six months of ⁸²Rb-chloride PET/CT MPI between January 2017 and July 2022. From this cohort, 162 patients who underwent ⁸²Rb-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 ¹⁸F-FDG uptake.

Results:
A total of 209 extracardiac findings were noted on CTAC in the target cohort, with 108 demonstrating positive ¹⁸F-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 ¹⁸F-FDG uptake, particularly in smokers (chi-squared value = 26.4, P < 0.001). In non-smokers, while isolated pulmonary nodules had no association with ¹⁸F-FDG uptake, those accompanied by lymphadenopathy exhibited a trend towards significant association with ¹⁸F-FDG uptake (chi-squared value = 10.9, P = 0.052).

Conclusions:
Extracardiac findings observed on CTAC during ⁸²Rb-chloride PET MPI in patients without a history of cancer are associated with subsequent ¹⁸F-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.