Fig. 2. (A) Ultrasonogram of a papillary thyroid carcinoma (arrow) in the isthmus. (B) Schematic illustration of the structures used to define groups in this study. Tumors (solid circle) for which the median line (arrow) was located between the lateral margins of trachea were classified as group I; all others (dotted circle) were classified as group II. RL, right lobe; RI, right isthmus; LI, left isthmus; LL, left lobe.
