Imaging recommendation · Abdomen · Pelvis

Insulinoma — pre-operative localization imaging

Q: What's the alternative imaging for insulinoma — pre-operative localization imaging when ct/mri non-diagnostic — small lesion suspected?

Endoscopic ultrasound (EUS) (no contrast).

Q: What's the alternative imaging for insulinoma — pre-operative localization imaging when occult source despite eus + ct/mri?

Selective intra-arterial calcium stimulation with hepatic venous sampling (IR) (iv contrast).

Q: What's the alternative imaging for insulinoma — pre-operative localization imaging when men1 — multifocal screening?

MRI — MRI pancreas + DOTATATE PET-CT (iv contrast).

Recommended: Multiphase pancreas-protocol CT or MRI is the preferred imaging study for insulinoma — pre-operative localization imaging. After biochemical confirmation (hypoglycemia + inappropriate insulin/C-peptide on 72-h fast).

Recommended study

Multiphase pancreas-protocol CT or MRI

CT IV contrast Preferred Abdomen · Pelvis Outpatient Reviewed 2026-05

After biochemical confirmation (hypoglycemia + inappropriate insulin/C-peptide on 72-h fast). Insulinomas are typically small (< 2 cm) and hypervascular — multiphase pancreas CT (arterial + portal venous) or contrast-enhanced MRI with hepatobiliary phase. Endoscopic ultrasound (EUS) is highly sensitive for small lesions. DOTATATE PET-CT has variable sensitivity for insulinoma (lower somatostatin receptor density vs other NETs).

If the default doesn't apply

CT/MRI non-diagnostic — small lesion suspected

Endoscopic ultrasound (EUS) No contrast

Occult source despite EUS + CT/MRI

Selective intra-arterial calcium stimulation with hepatic venous sampling (IR) IV contrast

MEN1 — multifocal screening

MRI MRI pancreas + DOTATATE PET-CT IV contrast

Watch-outs

DOTATATE for insulinoma

Sensitivity is lower than for other pancreatic NETs (~50%) — don't rely on a negative DOTATATE to exclude insulinoma.

Multifocality in MEN1

Look for additional pancreatic NETs, parathyroid, pituitary lesions — screen the whole syndrome.

Pearls

Insulinomas: avidly arterial-enhancing, < 2 cm, distributed throughout pancreas.
Arterial-phase imaging is the highest-yield single phase for detection.
EUS sensitivity approaches 90% for head/body lesions, lower in the tail.
Surgical cure rate > 90% for solitary insulinoma — accurate localization is the whole point.