Whole Body 111In-exendin-4 Imaging Study in Insulinoma Patients

Insulinomas arise from pancreatic cells and are the most frequent hormone-active tumours of the pancreas. Insulinomas produce insulin and can become life threatening if they cannot be localised and removed surgically. Complete tumour resection cures most patients, hence surgery is the treatment of choice for begin and malignant insulinomas. The potential for surgical cure necessitates accurate tumour localisation before surgery because preoperative imaging facilitates the detection of small localised, multiple and metastatic insulinomas. However, the successful localisation of insulinomas is an challenging problem since approximately 30% of insulinomas cannot be visualised radiographically.

A novel nuclear medicine scanning method using radioactive exendin-4 (111In-exendin-4) has recently been developed for imaging of insulinomas. 111In-exendin-4 accumulates specifically in insulinoma cells via the glucagon-like peptide-1 (GLP-1) receptor. The accumulation of 111In-exendin-4 can be visualised by the use of a special camera (Single Photon Emission Computed Tomography (SPECT) camera) that detects radioactivity and lights up tumours as hot spots.

The decision to perform surgery is independent of this study. If surgery is performed a small sample of the tumor will be used for identifying the sites where 111In-exendin-4 binds to the tumor.

Inclusion criteria

• Biochemically proven endogenous hyperinsulinism confirmed by hypoglycaemia with neuroglycopenic symptoms, inadequately high serum insulin and C-peptide concentrations and negative sulfonylurea screening as well as low serum beta-hydroxybutyrate concentrations
• Able and willing to provide written informed consent

Exclusion criteria

• Renal insufficiency (creatinine > 140 micromol/l)
• Pregnancy or positive pregnancy test which will be performed in all patients without contraception and aged < 50 years
• Allergy to exendin-4 (Byetta®)