47-Year-old male with PTC in left thyroid lobe (arrow). The image illustrates incorrect placement of calipers for measurement of size (distances A and B on the image) of the PTC. Distance A and distance B have been measured in the plane of the thyroid gland, whereas ACR TI-RADS describes measurements should be recorded along the orientation of the nodule, i.e., axes of maximum dimension of the nodule in the transverse image and maximum dimension perpendicular to the first measurement. The two lines drawn perpendicular to one another in the image represent the accurate technique for measuring size of nodules. Inaccurate placement of calipers for measuring a PTC on AS at baseline or follow-up may lead to false impression of progression and discontinuation of AS