Determination of thyroid volume using computerized ultrasonography and its clinical application

Abstract

A new method for determining thyroid gland volume was developed by means of computerized ultrasonography. A maximum area of the thyroid (S) was obtained from coronal sections and a maximum thickness (C) was obtained from sagittal sections. The thyroid volume was then calculated by SXC. The volume of phantoms and pig thyroids obtained by this method was identical with the actual volume. The thyroid volume in this method correlated well with the estimated volume in patients with Graves' disease undergoing thyroidectomy (r = 0.954). The measurement was then performed in 56 healthy subjects (male 28, female 28, age 15-68 y.o.) and 126 patients with thyroid diseases. The thyroid volume in healthy men was significantly larger than that in women (18.4 +/- 6.1 ml vs 13.9 +/- 4.9 ml, Mean +/- SD, p less than 0.01). The thyroid volume in normal subjects correlated with body height, body weight or body surface area (p less than 0.01), which may explain the sex differences. An attempt was made to calculate the prospective thyroid volume (Y ml) from body height as follows; Y = 0.425 X - 52.8, X; body height (cm). Four out of thirty patients with untreated Graves' disease had a gland volume of the normal range, but in all patients the thyroid volume was larger than the prospective volume. The thyroid volume and the rate of volume increase (determined thyroid volume/calculated prospective volume) were correlated with the serum levels of T3, T4 concentration in the untreated stage. The volume and the rate of volume increase did not correlate with serum TSH receptor antibody activity. The thyroid volume in patients with Graves' disease who had been in remission (33.0 +/- 13.5 ml) was significantly smaller than that in untreated patients (51.8 +/- 24.4 ml, p less than 0.02). These findings indicate that the present method is reliable and clinically useful for the investigation of thyroid diseases.