Insulinoma ultrasound

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

Transabdominal ultrasound has low sensitivity varying between 0 to 66% in detecting insulinoma. The sensitivity increases with the use of more invasive technique including endoscopic ultrasound (93%) and intra-operative ultrasound (86%). Hypo-echoic lesions and hypervascular mass are seen on the ultrasound.

• Ultrasound may be helpful in the diagnosis of insulinoma. The sensitivity varies from 0 to 66%. Smaller tumors are difficult to detect especially those on the tail of the pancreas. Findings on a trans-abdominal ultrasound suggestive of insulinoma include:^[1]
  • Low echogenicity
  • Hypervascularity on the doppler

• An ultrasound may be helpful in the diagnosis of complications of malignant insulinoma, which include:
  • Liver metastasis

This is an invasive ultrasound which can be done pre-operatively. The use has been increased with the increase in sensitivities from 40 to 93%, more accurate in diagnosing pancreatic head insulinomas. It is supported as the primary diagnostic modality for the diagnosis of pancreatic neuroendocrine tumors (which includes insulinoma). The advantages include:^[1][2][3]

• Visualization of smaller tumors (2mm)
• Detection of invasion and local metastasis
• Higher spatial resolutions

The disadvantages are:

• Invasiveness
• High cost
• Availabilty and expertise

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The use was introduced in 1981 and used to localize non-palpable lesions and tumors which are in close proximity to pancreatic and bile ducts. They can localize the tumors in 86% of cases when performed during an open or laparoscopic surgery. ^[4][5]

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