Transabdominal ultrasound has low sensitivity varying between 0-66% in detecting insulinoma. The sensitivity increases with the use of more invasive endoscopic ultrasound (93%) and intraoperative ultrasound (86%). Hypoechoic lesion and hypervascular mass are ultrasonographic findings.

• Ultrasound may be helpful in the diagnosis of insulinoma. The sensitivity varies from 0-66%. The smaller tumor is difficult to detect especially those on pancreas tail. Findings on a transabdominal 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. Its use has been increased with improve in its sensitivity. Endoscopic ultrasound is more accurate for pancreatic head insulinomas. It is the primary diagnostic modality for the diagnosis of pancreatic neuroendocrine tumors (which includes insulinoma).^[1][2][3]

The advantages are:

• It enables visualization of smaller tumors (2 mm)
• Local metastasis and invasion can be detected
• Higher resolutions

The disadvantages are invasiveness, high cost, availability, and expertise. {{#ev:youtube|TF1phjhRZLg}}

It was introduced in 1981 and used to localize non-palpable lesions and those who are in close proximity to pancreas and bile ducts. This method can localize tumors in 86% of cases when performed during an open or laparoscopic surgery.^[4][5]