Normal Uptake of 68Ga-DOTA-TOC by the Pancreas Uncinate Process Mimicking Malignancy at Somatostatin Receptor PET

Purpose: To characterize a commonly occurring increased uptake by the uncinate process of the pancreas at PET/CT using Ga-68-DOTA-d-Phe(1)-Tyr(3)-octreotide (Ga-68-DOTA-TOC). This tracer has replaced In-111 pentetreotide (OctreoScan (R)) for somatostatin receptor scintigraphy at our laboratory. Methods: Fifty of our first 74 PET/CT examinations with Ga-68-DOTA-TOC could be evaluated in retrospect. None of these patients had surgery or showed any pathology in the pancreas head at the concomitant CT. Results: Thirty-five of the 50 examinations (70%) showed an uptake by the uncinate process sufficiently intense to be interpreted as pathologic and simulating a tumor. Mean SUVmax was 9.2. Mean SUVmean using an isoactivity cut-off of >75% and >50% was 7.8 and 6.0, respectively. Volume calculations of the uncinate process activity using these definitions gave 0.9 mL and 4.2 mL, respectively. Conclusion: There is a frequent physiological uptake of Ga-68-DOTA-TOC by the pancreas uncinate process. This may be caused by an accumulation of pancreatic polypeptide-containing cells expressing somatostatin receptors. If there is a normal finding at concomitant diagnostic CT, this uptake should be regarded as physiological.