Imaging

Insulinoma

Preliminary Diagnosis: Insulinoma

I. What imaging technique is first-line for this diagnosis

  • CT of the abdomen and pelvis with IV contrast, pancreas protocol

II. Describe the advantages and disadvantages of this technique for insulinoma.

Advantages

  • Has good spatial resolution and allows for localization and enhancement characterization of pancreatic endocrine tumors

  • Has high sensitivity

  • Can identify hepatic and other metastatic lesions

  • Can identify non-hyperfunctioning pancreatic endocrine tumors

Disadvantages

  • Involves ionizing radiation

  • May require complementary imaging

III. What are the contraindications for the first-line imaging technique?

  • Known allergy to intravenous contrast

  • Decreased renal function

  • Pregnancy

IV. What alternative imaging techniques are available?

  • MR with and without contrast

  • Angiography

  • Nuclear imaging: options and availability will vary by institution

V. Describe the advantages and disadvantages of the alternative techniques for insulinoma.

MR with and without contrast

Advantages

  • Lack of ionizing radiation

  • Has comparable sensitivity and ability to identify metastases as CT

Disadvantages

  • Longer scan time

  • Requires a higher level of patient compliance and can be more prone to artifact

Angiography

Advantages

  • Allows for evaluation of functional status

  • Can be diagnostic

Disadvantages

  • Use of ionizing radiation

  • Limited to patients who can tolerate IV contrast

Nuclear imaging

Advantages

  • Clinical utility may vary depending on the type of endocrine neoplasm. For instance, gastrinomas may have a greater imaging sensitivity than insulinoma due to relatively higher expression of somatostatin receptors.

Disadvantages

  • Use of ionizing radiation

  • Nuclear imaging options and availability will vary by institution. Consultation is recommended to optimize the study.

VI. What are the contraindications for the alternative imaging techniques?

MR

  • Inability to cooperate for the exam

  • Presence of non-MR compatible metal

  • Poor renal function

Angiography

  • Poor renal function

  • Hypocoagulable state: elevated prothrombin time/internationalized normal ratio (PT/INR), low platelets

References

Lewis, RB, Lattin, GE, Paal, E. "Pancreatic endocrine tumors: radio-clinicopathologic correlation". Radiographics. vol. 30. 2010. pp. 1445-1464.

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