Variable Cardiac 18FDG Patterns Seen in Oncologic Positron Emission Tomography Computed Tomography Importance for Differentiating Normal Physiology From Cardiac and Paracardiac Disease

Purpose: Cardiac fluorine-18-fluorodeoxyglucose ((18)FDG) uptake is known to be variable in fasting oncologic positron emission tomography computed tomography studies. Increased posterolateral and basal (18)FDG activity have been reported with the basal pattern ascribed to radiation injury. The purpose of this study was to investigate the spectrum of normal cardiac (18)FDG findings seen in oncologic patients. Materials and Methods: Men < 35 years of age and women < 45 years of age seen over a 3-year period were included. A visual assessment of (18)FDG cardiac activity was performed using a 12-segment model of the heart by 2 observers. Focal papillary muscle activity was not included in the analysis. Results: Of 65 patients who met the entry criteria, increased (18)FDG activity was observed in the base of the heart in 37 (57%) patients. This was most common in the lateral-basal wall in 35 (54%) patients, followed by posterior-basal wall in 21 (32%) patients, anterior-basal wall in 10 (15%) patients, and basal-septum in 10 (15%) patients. Suppression of total cardiac activity was present in only 6 (9%) patients in spite of adequate fasting. Diffuse cardiac activity was seen in 9 (14%) patients. The previously reported increased posterolateral pattern was present in only 9 (14%) patients. Conclusion: This study confirms variable fasting (18)FDG cardiac activity with a predominant basal pattern not associated with radiation injury. Knowledge of these patterns is important for recognition of possible underlying cardiac ischemia, tumor, or other inflammatory conditions encountered during interpretation of oncologic positron emission tomography computed tomography studies.