REGIONALIZATION OF OCCULT PANCREATIC INSULINOMAS WITH THE ARTERIAL STIMULATION VENOUS SAMPLING (ASVS) TECHNIQUE

Non-invasive modalities (ultrasound, computerized tomography, MRI and somatostatin receptor scintigraphy) often fail to localize insulinomas smaller than 1.5 cm in diameter, Recently, regionalization of such oc cult insulinomas was facilitated by the arterial stimulation and venou s sampling (ASVS) technique, using calcium as the insulin secretagogue . However, so far experience with this technique has been limited to a few tertiary referrals centres worldwide, In these case studies we re port our experience in three consecutive patients with occult insulino mas, Three consecutive patients (all men 34, 51 and 56 years of age) w ith insulin-mediated hypoglycaemia were studied, Diagnosis of insulin hypersection was established by the finding of a high amended insulin: blood sugar ratio during fasting, Localization of a pancreatic mass le sion was unsuccessful by ultrasound, CT and/or MRI in all patients, Tw o patients had negative octreotide scans, In all patients after the in fusion of calcium sequentially into the gastroduodenal, splenic and th e superior mesenteric arteries, insulin levels rose significantly in r ight hepatic vein samples giving rise to diagnostic gradients from the splenic artery (in 2 patients) and gastroduodenal artery (in 1 patien t), regionalizing insulinomas in the tail and head or neck of the panc reas respectively, The simultaneously obtained angiogram was positive in only 1 patient, in whom it corresponded to the insulin gradient, Re gionalization of these occult tumours was subsequently confirmed at la paroscopy in the 2 patients operated, It is concluded, that the arteri al stimulation Venous sampling technique is an effective method in reg ionalizing occult insulinomas and should complement invasive angiograp hy whenever the latter procedure is performed.