Reducing inter-observer variation in thyroid volume calculation using a new formula and technique

Objective: Ultrasound (US) measurement of thyroid volume is used in diagnosis and follow-up of patients with thyroid disease. We assessed a new formula and technique for thyroid volume calculation, based on an automatically continuous trace transverse surface area (aTSA) calculation, to ascertain where this technique could reduce inter-observer variation. Methods: Three observers with a different level of US expertise, using a 12–5 MHz linear transducer, examined 25 volunteers. Inter-observer variations were calculated for diameter measurements and for the thyroid lobe volume calculations using the single factor ANOVA method. Results: Using the new technique and formula, no statistically significant differences existed, in contradistinction to using the classical formula for an ellipsoid ( P=0.02). Conclusion: When thyroid volume measurements are required, we recommend using a new method of thyroid volume calculation based on the use of an automatically calculated continuous trace aTSA measurement to avoid significant inter-observer variation in calculation of thyroid lobe volumes