A team of researchers have resolved a non-invasive method by which the position of very small pancreatic tumors called insulinomas can be precisely detected. This non-invasive method of detection will allow surgeons to successfully achieve surgical removal of tumor growths less than 1cm in diameter.
The observations were presented at the joint International Congress of Endocrinology/ European Congress of Endocrinology dated 7 May 2012. University Hospital at Bern’s clinical researcher of the Endocrinology Department, Professor Emanuel Christ and his research team have observed that a specific receptor type is present in high densities on the cell surfaces of insulinomas, which can be targeted using radioactively labelled drug. A conventional computerised tomography (CT) scan integrated with 2-D/3-D Single Photon Emission Computed Tomography (SPECT) technique has been used for patients while scanning to identify the drug’s binding location with insulinoma cells, thereby allowing tumor detection as small as 1 cm in diameter.
Thirty patients (12 women and 18 men) were infused with the drug. Following the injection, scanning was conducted by the researchers after 30 minutes, 4-, 23-, 96-, and 168-hours. SPECT imaging with 111In-exendin-4 precisely detected one malignant insulinoma, 23 benign insulinomas, two islets hyperplasia and two uncharacterised lesions. Conventional imaging (MRI), computerised tomography (CT) and endosonography were successfully employed for tumor detection in 17 patients. No false negative results occurred.
Furthermore, this technique was used to identify an islets hyperplasia and an additional malignant insulinoma. The positive predictive value of the test was 85%, whereas the negative value was predicted to be 100%.
Surgical removal of tumours was achieved following the scans. The tissues were then analyzed for diagnosis determination.
For detecting small insulinomas, existing invasive approaches such as arterial stimulation with venous sampling (ASVS) has been practiced.
Prof Christ and his team anticipate analyzing another 2-D/3-D nuclear medicine imaging technique called positron emission tomography (PET), to be effective for more improved tumour localisation.