Kwadwo Antwi

Localization of hidden Insulinomas with 68Ga-DOTA-exendin-4 PET/CT: A Pilot Study

111In-DOTA-exendin-4 SPECT/CT has been shown to be highly efficient in the detection of insulinomas. We aimed at determining whether novel PET/CT imaging with [Nle14,Lys40(Ahx-DOTA-68Ga)NH2]exendin-4 (68Ga-DOTA-exendin-4) is feasible and sensitive in detecting benign insulinomas. Methods: 68Ga-DOTA-exendin-4 PET/CT and 111In-DOTA-exendin-4 SPECT/CT were performed in a randomized cross-over order on 5 patients with endogenous hyperinsulinemic hypoglycemia. The gold standard for comparison was the histologic diagnosis after surgery. Results: In 4 patients histologic diagnosis confirmed a benign insulinoma, whereas one patient refused surgery despite a positive 68Ga-DOTA-exendin-4 PET/CT scan. In 4 of 5 patients, previously performed conventional imaging (CT or MR imaging) was not able to localize the insulinoma. 68Ga-DOTA-exendin-4 PET/CT correctly identified the insulinoma in 4 of 4 patients, whereas 111In-DOTA-exendin-4 SPECT/CT correctly identified the insulinoma in only 2 of 4 patients. Conclusion: These preliminary data suggest that the use of 68Ga-DOTA-exendin-4 PET/CT in detecting hidden insulinomas is feasible.

Preoperative localization of adult nesidioblastosis using (68)Ga-DOTA-exendin-4-PET/CT.

The term ‘‘nesidioblastosis’’ has been used to denote histopathological findings such as neogenesis from pancreatic ductal epithelium in parallel with b-cell hyperplasia and hypertrophy (1). This entity was first described in children and neonates and is characterized by endogenous hyperinsulinemic hypoglycemia. The incidence rate in adults ranges between 0.5 and 7 %. The pathophysiological mechanisms in adults are ill-defined. The preoperative distinction between insulinoma and nesidioblastosis is of primordial importance since the therapeutical strategies are different, ranging from a enucleation in the case of insulinoma up to a 70–80 % pancreatectomy in the case of nesidioblastosis. Clinically, the distinction between insulinoma and nesidioblastosis is not always possible. Preoperative imaging including MRI, CT, and endosonography is not diagnostic in adult nesidioblastosis, and invasive investigation using selective arterial calcium stimulation and venous sampling (ASVS) is recommended. Although this investigation is often helpful, it is an invasive procedure with the associated risks. Recently, we have shown that targeting glucagon-like peptide-1 receptor (GLP-1R) using In-DOTA-exendin-4 SPECT/CT is a very sensitive non-invasive method to localize benign insulinoma (2). Whether GLP-1R targeting is useful in adult nesidioblastosis is currently unknown.

Application of Ga(68) -DOTA-exendin-4 PET/CT to localize an occult insulinoma.

A 49 year old female presented to our Neuroendocrine Tumour (NET) centre with recurrent severe and disabling hypoglycaemia. She had previously been extensively investigated with a clinical and biochemical diagnosis of endogenous hyperinsulinemic hypoglycaemia although the source of hormonal hypersecretion could not be localised with MRI, EUS and (111) In-Octreotide scans. After extensive discussion the patient opted for blind surgical resection undergoing a pylorus-preserving pancreaticoduodenectomy in December 2010. Histological examination of the resected operative specimen demonstrated a normal pancreas with no evidence of neuroendocrine tumour. Consistent with this, post-surgery her hypoglycaemic symptoms persisted with fasting capillary blood glucose of 2.1-6.0 mmol/l with increasing hypoglycaemia unawareness. Consequently she sought alternative clinical opinions from two European Neuroendocrine Tumour Society (ENETS) Centres of Excellence who investigated her collaboratively. This article is protected by copyright. All rights reserved.

Preoperative Glucagon-like peptide-1 receptor imaging reduces surgical trauma and pancreatic tissue loss in insulinoma patients: a report of three cases

BackgroundInsulinomas are rare tumors, in the majority of cases best treated by surgical resection. Preoperative localization of insulinoma is challenging. The more precise the preoperative localization the less invasive and safer is the resection. The purpose of the study is to check the impact of a new technique to localize insulinoma on the surgical strategy.FindingsWe present exact preoperative localization with Glucagon-like peptide-1 receptor (GLP-1R) imaging. This allows a more precise resection thereby reducing surgical access trauma, loss of healthy pancreatic tissue and increasing safety and quality of the surgical intervention.ConclusionWith the help of precise preoperative localization of insulinoma with GLP-1R imaging the surgeon is able to minimize the amount of resected healthy pancreatic tissue. We hypothesize that GLP-1R imaging will become a preoperative diagnostic tool to be used for many patients scheduled for open or laparoscopic insulinoma resection.