DOI: 10.1007/s00259-018-4101-5Pages: 2318-2327

Comparison of glucagon-like peptide-1 receptor (GLP-1R) PET/CT, SPECT/CT and 3T MRI for the localisation of occult insulinomas: evaluation of diagnostic accuracy in a prospective crossover imaging study

1. University Hospital Basel, Clinic of Radiology and Nuclear Medicine

2. University Hospital Basel, Centre for Neuroendocrine and Endocrine Tumours

3. University Hospital Basel and University of Basel, Clinical Trial Unit, Department of Clinical Research

4. University Hospital of Bern, Department of Visceral Surgery

5. University Hospital Basel, Division of Endocrinology, Diabetology and Metabolism

Correspondence to:
Damian Wild
Tel: +41 61 328 6683




Benign insulinomas are the most prevalent cause of endogenous hyperinsulinaemic hypoglycaemia (EHH) in adults, and because of their small size are difficult to localise. The purpose of the study was to test the diagnostic accuracy and clinical impact of glucagon-like peptide-1 receptor (GLP-1R) PET/CT using 68Ga-DOTA-exendin-4 in consecutive adult patients referred for localisation of insulinomas. The results were compared with 111In-DOTA-exendin-4 SPECT/CT, study-MRI and previously performed external CT and/or MRI (prior external CT/MRI).


We prospectively enrolled patients with neuroglycopenic symptoms due to EHH. GLP-1R PET/CT, SPECT/CT and study-MRI were performed in a randomised, crossover order within 3–4 days. The reference standard was surgery with histology and treatment outcome.


From January 2014 until March 2017, 52 patients were recruited. All imaging and invasive procedures before recruitment identified suspicious lesions in 46.2% of patients. GLP-1R PET/CT, SPECT/CT and study-MRI detected suspicious lesions in 78.8%, 63.5% and 63.4% of patients, respectively. In 38 patients, conclusive histology was available for final analysis.

Accuracy (95% confidence interval) for PET/CT, SPECT/CT, study-MRI and prior external CT/MRI was 93.9% (87.8–97.5%), 67.5% (58.1–76.0%), 67.6% (58.0–76.1%) and 40.0% (23.9–57.9%), respectively (all P values < 0.01, except comparison of SPECT/CT and study-MRI with a P value = 1.0). Impact on clinical management was 42.3%, 32.7% and 33.3% for PET/CT, SPECT/CT and study-MRI, respectively. Percentage reading agreement was 89.5%, 75.7%, and 71.1% for PET/CT, SPECT/CT and study-MRI, respectively.


68Ga-DOTA-exendin-4 PET/CT performed significantly better than 111In-DOTA-exendin-4 SPECT/CT and MRI in the localisation of benign insulinomas and should be considered in patients where localisation fails with CT/MRI (, NCT02127541).

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  • Accepted: Jul 18, 2018
  • Online: Jul 28, 2018

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