# Effects of Glucose Intolerance on Physiological Accumulation in Salivary Glands and Palatine Tonsils During 18F-Fluorodeoxyglucose Positron Emission Tomography

## TL;DR

High blood sugar reduces natural FDG uptake in salivary glands and tonsils during PET scans, affecting visibility in diabetic patients.

## Contribution

This study identifies how chronic hyperglycemia and diabetes impact physiological FDG accumulation in specific head and neck tissues during PET/CT.

## Key findings

- Hyperglycemic patients showed significantly lower SUVmax in salivary glands and tonsils compared to controls.
- Visible FDG uptake in parotid and tonsillar tissues was less common in hyperglycemic and diabetic patients.
- Tonsillar uptake was observed in 90% of controls but only two-thirds of diabetic patients.

## Abstract

Purpose: We evaluated the effects of chronic hyperglycemia on physiological accumulation in salivary glands and tonsils during 18F-fluorodeoxyglucose positron emission tomography (FDG-PET/CT).

Materials and methods: 12,738 patients underwent whole-body FDG-PET/CT in our institute during the study period. Of these, the case group comprised 777 patients with a blood glucose (BG) level >140 mg/dL; the control group comprised an equal number of randomly selected age- and sex-matched individuals with a BG level <110 mg/dL. Within the case group, the diabetic subgroup was defined as individuals with a BG level >200 mg/dL. Visual assessment and accumulation intensity among tissues were compared between the case and control groups, including (1) the mean difference in maximum standardized uptake value (SUVmax), (2) the difference in the proportion of patients with visible tissues on maximum intensity projection images, and (3) differences between the diabetic subgroup and the control group.

Results: Parotid, submandibular, sublingual, and tonsillar tissues all showed significantly lower SUVmax in the case group than in the control group. The proportions of individuals with visible uptake in the parotid and tonsillar tissues and in the sublingual gland were significantly smaller in the case group than in the control group. Tonsillar uptake was observed in more than 90% of individuals in the control group but in two-thirds of patients in the diabetic subgroup. Accumulation in the parotid and submandibular glands was visible in approximately 80% of individuals in the control group but only half of patients in the diabetic subgroup.

Conclusion: Physiological accumulation in salivary glands and tonsils is significantly reduced among individuals with hyperglycemia or diabetes.