Congenital hyperinsulinism: 18F-L-DOPA PET/CT localizes the focal lesions

Objectives Congenital Hyperinsulinism (CHI) is a heterogeneous disease characterized by inappropriate insulin secretion in the pancreatic β-cells with risk of severe brain damage due to hypoglycemia. Two major subtypes with focal or diffuse affection of beta-cells, are seen. The focal form is associated with paternal ABCC8 or KCNJ11 mutation plus a maternal loss of chromosome 11p15 in a focal area of the pancreas and can be treated surgically provided the lesion can be detected. The combination of genetics and 18F-L-DOPA PET/CT imaging helps demonstrating the character and localisation of the disease thus giving the surgeon ability to perform curative limited pancreatic surgery.

Methods 31 patients with CHI, aged two weeks to 10 years were admitted to our hospital between 2006 and 2013. Bidirectional sequencing of ABCC8 and KCNJ11 was performed, and all had a 18F-L-DOPA PET/CT scan. All scans were performed 10, 35 and 60 min post injection. SUV ratios between focal lesion and normal pancreatic tissue were determined.

Results 13 patients had a genetic profile predictive of a focal lesion, PET/CT found a focal lesion in 11 of these. The SUV ratios ranged from 1.35 to 4.65. The remaining 20 patients all had diffuse uptake in the pancreas. The 11 patient with focal lesions on PET/CT all underwent curative limited pancreatic surgery, and intraoperative histology confirmed the diagnosis. Five of the 20 patients with prediction of diffuse CHI underwent extensive surgery (70-95% pancreatectomy), four of them had diffuse CHI on histology, one had extensive focal CHI with a later diagnosis of Beckwith-Wiedemann Syndrome.

Conclusions Genetic profiling had a misclassification rate of 10% in predicting diffuse versus focal CHI. 18F-L-DOPA PET/CT is a helpful tool in guiding the surgeons to curative limited pancreatic surgery.