Comparison of radioisotopic and ultrasonic scanning in the evaluation of neonatal hypothyroidism.
BACKGROUND
Technetium-99m pertechnetate (Tc-99m) scan is presently the best diagnostic modality to delineate the anatomy of the neonatal thyroid. Because several factors will inhibit Tc-99m uptake in a normal thyroid gland and the Tc-99m scan requires expensive equipment and sometimes raises fear of radiation in parents, the ultrasonography might be an important complementary method for neonatal thyroid disorders. We described our experience with ultrasonography of the thyroid in 52 infants with suspected congenital hypothyroidism to compare the results obtained by using Tc-99m imaging in the same infants.


METHODS
From Dec. 1991 to May 1992, 52 neonates with suspected congenital hypothyroidism by newborn screening were referred to Veterans General Hospital-Taipei for confirmatory diagnoses. All of them were investigated with Tc-99m and ultrasonography of the thyroid gland. Results of Tc-99m scan and ultrasonography were compared and analyzed.


RESULTS
The ultrasonography failed to identify any ectopic gland and all cases were misinterpreted as hypoplasia or hemiagenesis of thyroid gland, but it never misinterpreted them as normal thyroid glands. The ultrasound never misinterpreted normal thyroid gland, while the Tc-99m scan misguided a normal gland as an athyreotic gland.


CONCLUSIONS
The ultrasonography may be adopted as the first line image examination for the babies with suspected congenital hypothyroidism. If sonography shows abnormal thyroid gland such as hypoplasia, hemiagenesis or agenesis, the isotopic scan may be a good complementary method to confirm the diagnosis.
Niu
D M
DM
Department of Pediatrics, Veterans General Hospital-Taipei, Taiwan, R.O.C.
Chao
T
T
Tiu
C M
CM
Chou
Y H
YH
Chu
Y K
YK
Hwang
B
B
D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000000981:diagnostic imaging*; D007223:Infant; D008297:Male; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D013670:Sodium Pertechnetate Tc 99m; D013961:Thyroid Gland / Q000000981:diagnostic imaging; D014463:Ultrasonography
D013670:Sodium Pertechnetate Tc 99m