Seasonal Temperature Changes Do Not Affect Cardiac Glucose Metabolism

Area of Science:

• Nuclear Medicine
• Cardiovascular Imaging
• Metabolic Imaging

Background:

• Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is crucial for diagnosing cardiac inflammation, like sarcoidosis.
• Physiological myocardial FDG uptake can obscure pathological cardiac glucose metabolism.
• Factors influencing myocardial glucose metabolism include fasting, blood glucose, and hormones, but environmental temperature's effect is unknown.

Purpose of the Study:

• To investigate the impact of seasonal outdoor temperature variations on myocardial FDG uptake and heterogeneity.
• To determine if patient warming is necessary before cardiac PET scans to mitigate physiological myocardial FDG uptake.

Main Methods:

• Retrospective analysis of 29 cancer patients who underwent cardiac PET scans in both warm summer and cold winter months.
• Quantitative assessment of myocardial, liver, and mediastinal standardized uptake values (SUVs).
• Evaluation of cardiac heterogeneity and FDG uptake patterns, comparing with age and BMI.

Main Results:

• No significant difference in mean myocardial FDG uptake was observed between summer and winter scans.
• Average outdoor temperature did not correlate significantly with myocardial SUVmax in either season.
• Cardiac FDG uptake heterogeneity showed no significant seasonal variation.

Conclusions:

• Seasonal outdoor temperature variations do not appear to significantly influence myocardial FDG uptake or its heterogeneity.
• Pre-scan patient warming to reduce physiological myocardial FDG uptake in cardiac PET studies is likely unnecessary.