FDOPA and⁶⁸GaDotatate PET Imaging in Nesidioblastosis

Introduction: Nesidioblastosis also known as persistent hyperinsulinemic hypoglycemia of infancy or congenital hyperinsulinism occurs most commonly in infants and children. It presents with recurrent episodes of hypoglycemia due to high endogenous insulin levels. There is a focal and diffuse form of the disease depending on the extent of pancreatic involvement. Hyperplasia of the islet cells results in hyperfunctioning pancreatic β cells and the ensuing clinical disease. Medical treatment fails in several patients and surgery has been shown to be very effective in improving prognosis and even resolution of disease in the focal form. Several genetic mutations have been uncovered and these may also be predictive of prognosis. Anatomical imaging alone including ultrasound, CT and MRI are rarely able to detect any abnormality in the pancreas. PET plays a major role in the distinction between the focal and diffuse forms of the disease. It can also guide surgical intervention by providing information on the location of the focal hyperfunctioning islet cells. Imaging children and infants in this disease is quite challenging. We propose to show the benefit of using two PET tracers in this disease. FDOPA has been used quite successfully in the evaluation of nesidioblastosis. ⁶⁸Ga DOTATATE has also been described to be helpful. We illustrate in 3 scans focal disease in the pancreatic head. Illustrated in Figure 1, in a 2 month old baby boy with nesidioblastosis and a KCNJ 11 genetic mutation we can see the slight difference in visualization of focal pancreatic head uptake in a small baby between both tracers that have a different physiological distribution. ⁶⁸Ga DOTATATE has more uptake in the kidneys which may affect visualization of lesions in proximity to the kidneys and FDOPA with more uptake in the liver may also pose some challenge in detecting adjacent lesions. In Figure 2 focal uptake in the head of the pancreas is more apparent in an older 6 month old boy with nesidioblastosis. This latter was found to carry a heterozygous pathogenic mutation in the ABCC8 gene.

Conclusions: FDOPA and ⁶⁸Ga DOTATATE are critical in the evaluation of nesiodioblastosis patients. FDOPA as described in the literature seems to be slightly superior.

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