Assessment of selective arterial calcium stimulation and hepatic venous sampling to localize insulin-secreting tumours

Objective Non-invasive localization modalities such as ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI) often fail to localize insulinomas smaller than 2 cm in diameter. Recent studies have shown that the selective arterial stimulation and hepatic venous sampling (ASVS) techn ique using intra-arterial calcium as the insulin secretagogue facilitates t he regionalization of such occult insulinomas. This study assesses the sens itivity of ASVS in localizing insulin-secreting tumours. Subjects and methods Eleven consecutive patients (8 women), aged 29-82 year s, were studied over the past 4 years at our hospital. Hyperinsulinaemic hy poglycaemia due to an insulin-secreting tumour was proven in all patients. Calcium gluconate (0.025 mEq/kg body weight) was injected directly into the arteries supplying the pancreas and the liver. Insulin levels were measure d in samples taken from the right hepatic vein before and 30, 60 and 120 s after each injection. The ASVS technique was performed In all 11 patients; the results were compared with the surgical findings in 10 patients and the autopsy findings in 1 case. The ASVS results were also compared with the f indings of other, previously performed imaging modalities. Results ASVS correctly localized 4 insulin-secreting tumours to the head, 3 to the body, 1 to the tail, 2 to the tail or body of the pancreas and 1 to the liver. Thus, the sensitivity was 100% (11/11) whereas other localizati on techniques were less sensitive: 7/11 tumours were detected by angiograph y, 4/8 by endosonography, 3/8 by CT and 1/6 by MRI. Insulinomas (confirmed by histological examination), sized 4-25 mm, were found in 10 patients. All were cured by selective surgery and remained free of hypoglycaemia over th e next 1-4 years of follow-up. An insulin-secreting neuroendocrine tumour i n the liver was documented in 1 case at autopsy. Conclusions Arterial stimulation and hepatic venous sampling is a very sens itive technique for preoperative localization of insulin-producing tumours. It can help to plan minimally invasive surgery and to select an appropriat e strategy for patients suffering from malignant tumours in others.