Insulinoma other diagnostic studies

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Amandeep Singh M.D.[2]

Arterial calcium stimulation with hepatic venous sampling (ASVS) is an invasive diagnostic study which is used when all other imaging studies are inconclusive. ASVS is also the diagnostic test of choice for endogenous hyperinsulinism. Findings are noted after calcium stimulation of tumor supplying arteries and in the hepatic venous samples which show the positive response of a two-fold or greater increase in insulin levels.

• Arterial calcium stimulation with hepatic venous sampling (ASVS) may be helpful in the diagnosis of insulinoma when all other non-invasive methods and even invasive test such as endoscopic ultrasound have failed to localize the tumor. ASVS is also the diagnostic test of choice for endogenous hyperinsulinism. It provides a more accurate localization and reduces the risk of repeating surgeries. It has a greater sensitivity of 100% but the specificity of 20-50%. ^{[1][2][3][4][5]}

• Arteries commonly used in Arterial calcium stimulation
  • Splenic artery
  • Gastroduodenal artery
  • Superior mesenteric artery
  • Proper hepatic artery

• Intra-arterial administration of a hyperosmolar concentration of calcium in the vessels supplying the tumor will cause degranulation of cells within the neoplasm which releases insulin into the portal venous system. This results in a detectable rise in insulin levels in venous samples obtained from the hepatic vein. It is visualized under early arterial phase.
• Findings diagnostic of insulinoma include:
  • Well-defined, round or oval blushes of hyper-vascularity as compared to the parenchyma of the pancreas.
  • Positive response is determined by an increase in insulin concentration from baseline to two-fold peak or greater.

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