Abstracts
2000 Digestive Disease Week

# 2306 Intra-Arterial Calcium Injection (IACI)Test as Localizing Procedure in Insulinomas.
Claudio Pasquali, Diego Miotto, Cosimo Sperti, Francesco Meduri, Saula De Kreutzenberg, Sergio Pedrazzoli, Padova, Italy

Small insulinomas may be difficult to be found and resected at first operation. Intra-arterial calcium injection (IACI) test may be very useful in regionalizing small insulinomas. METHODS: From November 1993, 19 patients (11 M/8 F) with hypoglycemic syndrome suspected to have an insulinoma underwent angiography and IACI test as localizing procedure. US scan, CT-scan and/or MRI were performed before the IACI test in all pts. Calcium (0.015-0.025 mEq/Kg b.w.) was injected in each arterial branch supplying the pancreas and Insulin was assayed in the blood collected for 2 m. from the hepatic vein. Positive test was defined as a three-fold increase of insulin concentration after calcium injection. RESULTS: Fifteen patients (79%) had a positive IACI test. A peak of insulin secretion occurred after injection of a single artery in 12 cases, after injection in two arteries in three cases. All cases had a typical single adenoma (size <1 cm in six) resected at surgery. Only 8/15 patients (53%) had a positive non invasive imaging before angiography. Angiography alone (positive in 10/15 cases, 67%) detected 4 more insulinomas, but it was negative in 3/6 cases with a small (<1 cm) adenoma. Intraoperative ultrasound was positive in 12/13 cases; it was negative in the single (0.8 cm) adenoma not felt or seen at surgical exploration; it was resected on the basis of IACI test results. The IACI test was not localizing in four out of the 19 cases: a single adenoma with positive preoperative imaging showed no insulin rise after calcium injection. A slight Insulin rise following each of the artery injections occurred in a MEN 1 patient with a macroadenoma of the tail and diffuse nesidioblastosis. No insulin rise was seen in a malignant insulinoma with multiple liver metastases. Finally, no insulin rise was seen in a case later recognized to have hypoglycemia secondary to self administration of oral antidiabetics. All 17 patients with benign insulinomas were cured. CONCLUSION: IACI test correctly regionalized the source of insulin hypersecretion in 94% of cases with a typical single adenoma, including six cases with small (<1 cm) adenoma. Caution is needed in evaluating negative tests, possibly related to extended disease or other uncommon causes of hypoglicemia.