Diagnostic Imaging in Children

摘要

In this issue of the journal, two articles highlight the important roles of diagnostic imaging in the management of a common (urinary tract infection) and a rare (hyperinsulinaemic hypoglycaemia) paediatric condition. Persistent hyperinsulinaemic hypoglycaemia of infancy (PHHI) reported in this issue of our journal is a devastating disease requiring aggressive management in order to avoid brain damage as the patients are deprived of both glucose and ketones required for brain cell metabolism. Although the focal and diffuse forms of PHHI share an indistinguishable clinical presentation, they have different genetic basis and the surgical approach and outcome of the two conditions are different. Selective surgical removal of an identified focal lesion will result in a cure while in the diffuse form of PHHI, near total pancreatectomy is recommended. Magnetic resonance or computerised tomography imaging of the pancreas, intra-operative ultrasonagraphy and palpation are not reliable to differentiate the two forms. Pre-operative differentiation of the two conditions requires pancreatic venous sampling which is a technically demanding invasive procedure requiring general anaesthesia and the patients are subjected to the risk of hypoglycaemia as drug treatment with diazoxide, octreotide and nifedipine need to be stopped for 5 days before the test and blood sugar maintained by intravenous glucose infusion. Positron emission tomography (PET) performed with 18F-fluoro-L-dihydroxyphenylalanine (18F-fluoro-L-DOPA) has been used to detect neuroendocrine tumours and it has been found to be useful to differentiate the focal from the diffuse form of PHHI.1-4 18F-DOPA-PET of the pancreas is now available in Hong Kong and this procedure will greatly facilitate the diagnosis and management of such patients. However, surgery for both the focal and diffuse form of the disease remains technically demanding.