ESTIMATION OF THYROID-GLAND VOLUME BY SPIRAL COMPUTED-TOMOGRAPHY

The objective of this study was to test the accuracy of CT for the est imation of the volume of enlarged thyroid glands. An unenhanced spiral CT scan of neck and upper mediastinum was obtained in 36 patients wit h an enlarged thyroid gland. By manual segmentation the surface of the thyroid gland on 5-mm-thick slices was calculated; these surfaces wer e multiplied by the slice interval (10 mm) and summated to obtain the volume of the gland. All patients underwent a total or subtotal thyroi dectomy. 1 cm(3) of thyroid gland tissue was considered to weigh 1 g. A good correlation was found between the volume estimated by CT and th e weight at pathological examination of the resected gland (r = 0.98, p < 0.001), with a mean difference of + 12 % (range: + 57.3 to -13.9 % ). The volume calculation is reproducible among different observers (r = 0.99, p < 0.01). Computed tomography allows an easy, reliable and r eproducible volume determination of enlarged thyroid glands.