THYROID-NODULES IN THE FOLLOW-UP OF IRRADIATED INDIVIDUALS - COMPARISON OF THYROID ULTRASOUND WITH SCANNING AND PALPATION

In 1974 we began a prospective study of a cohort of 4296 individuals e xposed to therapeutic head and neck irradiation during childhood for b enign conditions. To define the role of thyroid ultrasonography in fol lowing irradiated individuals, we studied a subgroup of 54 individuals . They all had been screened between 1974-1976 and had normal thyroid scans and no palpable nodules at that time. Thyroid ultrasonography, t hyroid scanning, physical examination, and serum thyroglobulin measure ments were performed. One or more discrete ultrasound-detected nodules were present in 47 of 54 (87%) subjects. There were a total of 157 no dules, 40 of which were 1.0 cm or larger in largest dimension. These 4 0 nodules occurred in 28 (52%) of the subjects. Thirty (75%) of these 1.0-cm or larger nodules matched discrete areas of diminished uptake o n corresponding thyroid scans. The 10 that did not match (false negati ve scans for greater than or equal to 1.0-cm nodules) were the only no dules of this size in 7 subjects. Of 11 nodules 1.5 cm or larger, only 5 were palpable. Serum thyroglobulin correlated to the number (P = 0. 04; r(2) = 0.10), but not the volume of the thyroid nodules (P = 0.07; r(2) = 0.08). We conclude that thyroid nodules are continuing to occu r and are exceedingly common in this irradiated cohort of individuals. The results confirm that thyroid ultrasonography is more sensitive th an physical examination and scanning. However, thyroid ultrasound is s o sensitive and nodules so prevalent that great caution is needed in i nterpreting the results.