Radionuclide imaging in primary permanent congenital hypothyroidism.

Thyroid scintigraphy was performed in 69 consecutive infants with permanent primary congenital hypothyroidism (CH) detected by systematic neonatal thyroid screening using a rectilinear scanner or a gamma camera 15 minutes after the intravenous injection of 250 microCi Tc-99m sodium pertechnetate, immediately after the infants were fed. Immobilization of the infant in a supine position with the neck in hyperextension was achieved by a vacuum cushion without any sedation. Thyroid scintigraphy showed thyroid ectopia in 43 of the 69 CH infants, thyroid agenesis in 19, and goiter in the last 7 infants, respectively. The images were easily interpretable in all cases, even in very small ectopic glands in the lingual area, as there was no interference with extra-thyroidal uptake of the tracer, especially by the salivary glands. Our experience indicates that thyroid scintigraphy in the CH newborns can be performed immediately at the time of diagnosis of CH without technical difficulties. As thyroid scintigraphy is the only procedure allowing the distinction between thyroid agenesis and ectopia, and as the neurointellectual prognosis might be lower in the former than in the latter situation, thyroid scintigraphy in CH newborns contributes not only to the diagnosis but also the prognosis of the disorder.