Jean Verelst

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 μCi 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.

Quantitation of esophageal transit by means of 81mKr

A method for quantifying esophageal transit by means of 81mKr is described. The principal advantage of 81mKr compared with 99mTc is its ultra-short half-life with its consequences on radiation dose and counting statistics. Factors which may influence the esophageal transit time such as body posture, volume of the tracer, and the nature of the tracer were studied. The reproducibility of the technique is quite good and its capacity to detect minor esophageal transit disorders is demonstrated.

Abnormalities of esophageal transit in patients with sporadic nontoxic goitre

Esophageal transit (E.T.) was investigated in 122 consecutive euthyroid patients with scintigraphically proven goitre, and compared to 26 control subjects. E.T. was quantified using the 81mKr transit time, a highly sensitive technique capable of detecting even minor E.T. disorders. Abnormal E.T. was observed in 39% of goitrous patients, while it was normal in all controls. Occurrence of delayed E.T. was not correlated with either goitre firmness, the presence of symptoms of neck discomfort, difficulties in swallowing, or nodularity. E.T. delay was more frequent and more severe with larger goitres. In addition, E.T. delay was significantly correlated with asymmetry and “low lying” goitres. In summary, the present studies are the first demonstration of frequent E.T. anomalies in goitrous patients. The data suggest that E.T. impairment could be mediated by two mechanisms: a direct compression effect in patients with large, asymmetrical, partially retrosternal goitres; and an indirect functional esophageal anomaly in patients with small goitres.

Variability of the administered radioiodine doses for the treatment of hyperthyroidism in Belgium

Objective   When using radioiodine for hyperthyroidism there is no consensus regarding the administration of fixed or calculated doses. Guidelines do not specify the preferable approach or the parameters to use to calculate the dose. Therefore, the dose might be quite different with regard to the chosen procedure. This study was undertaken to evaluate the variability of the amount of radioiodine administered in Belgium in various cases of hyperthyroidism.