Physiological Distribution of 18F-FDG in the Spinal Cord of Disease-Free Subjects

Objectives: ¹⁸Fluorine-fluorodeoxyglucose (¹⁸F-FDG) uptake in the spinal cord is not unusual and may mimic metastatic disease. The physiological characterization and variability of spinal cord ¹⁸F-FDG metabolism provide valuable information, especially in patients with suspected malignancies. We aimed to investigate the physiological ¹⁸F-FDG uptake pattern within the spinal cord and its associations in a normal population.

Methods: We retrospectively analyzed ¹⁸F-FDG positron emission tomography/computed tomography images of 140 adult patients who were confirmed to be disease-free over a one-year follow-up period. The maximal and mean standard uptake values (SUV_max, SUV_mean) were measured at each mid-vertebral level from C1 to L5, and normalized to liver and blood pool uptake. Correlations between ¹⁸F-FDG uptake and patient demographics, clinical parameters, and environmental temperature were evaluated.

Results: ¹⁸F-FDG uptake demonstrated a decreasing trend from the cervical to lumbar vertebrae, with a notable increase at the lower thoracic levels (T11-T12). There was a significant negative correlation between ¹⁸F-FDG uptake and age (p<0.001), fasting glucose level (p=0.016), and diabetic status (p=0.003). No significant association was found between spinal cord ¹⁸F-FDG uptake and gender, weight, height, body mass index, ¹⁸F-FDG dose, or environmental temperature.

Conclusion: Normal distribution of ¹⁸F-FDG in the spinal cord of disease-free individuals decreases from cervical to lumbar levels, although it notably increases at the lower thoracic and mid-lower cervical levels. Uptake significantly decreases with age, with a higher fasting blood glucose level, and in diabetic patients.