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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