A Negative Correlation Between Blood Glucose Level and 68 Ga-DOTA-TOC Uptake in the Pancreas Uncinate Process

Purpose 68 Ga-DOTA-TOC uptake in the pancreas uncinate process is often found due to physiologic expression of somatostatin receptors (SSTR). We investigated the association of physiologic 68 Ga-DOTA-TOC uptake in the pancreas uncinate process with blood glucose level. Methods 68 Ga-DOTA-TOC PET scans acquired from 44 patients (male:female = 20:24, age = 50.8 ± 14.8y [mean ± SD]) were retrospectively analyzed. The blood glucose level (BGL) was examined before 68 Ga-DOTA-TOC injection. Patients diagnosed with diabetes mellitus and patients with BGL over 200 mg/dl were excluded. 68 Ga-DOTA-TOC uptake was measured by the maximum standardized uptake values (SUVmax). Additionally, SSTR-positive volume (SV) in the pancreas uncinate process was measured with two different thresholds: by SUV cutoff of 2.5 (SV 2.5 ) and 40% of SUVmax (SV 40% ). These measurements on 68 Ga-DOTA-TOC PET were correlated with BGL. Results The mean of SUVmax of the pancreas uncinate process was 6.51 ± 2.04. SV 2.5 was 17.81 ± 7.14 cm 3 , and SV 40% was 18.20 ± 8.83 cm 3 . A significant negative correlation was found between SUVmax of the pancreas uncinate process and BGL ( r = -0.37, p = 0.01). The ratio between SUVmax of the pancreas uncinate process and SUVmean of the pancreas body also showed a significance negative correlation with BGL ( r = -0.40, p = 0.01). SV 2.5 ( r = 0.27, p = 0.07) and SV 40% ( r = -0.151, p = 0.32) were not significantly correlated with BGL. Conclusion Physiologic 68 Ga-DOTA-TOC uptake in the pancreas uncinate process was negatively correlated with BGL. Our results suggested that glycemia could affect physiologic uptake of 68 Ga-DOTA-TOC.