Thyroid volume as measured by real-time ultrasound in cadavers was compared with direct measurements obtained by submersion. Length X width X thickness of the thyroid lobe multiplied by factor pi/6, correspond to a rotation ellipsoid, while the best calculated volume of the lobe is obtained by multiplying with the optimised correction factor f = 0.479. The correctness of this calculation is, by definition, 100%; average error of the method is 16%. The measurements are easy to do and require no additional equipment for planimetry or calculations. Volumetric analysis of the thyroid gland is especially necessary in assessing results of treatment and for measuring dosage in connection with radioiodine therapy.
