Figure 1.

For PTCs with homogeneous echogenicity (A), regions of interest (ROIs) are drawn to include the nodule (1) and the surrounding normal thyroid tissue (2). The mean gray scale values for the PTCs and the surrounding normal thyroid tissue were 44.0 and 70.5, respectively, and the UGSR was 0.625 (44.0/70.5). For NGs with homogeneous echogenicity (B), the regions of interest (ROIs) are drawn to include the nodule (1) and the surrounding normal thyroid tissue (2). The mean gray scale values for the NGs and the surrounding normal thyroid tissue were 70.0 and 84.2, respectively, and the UGSR was 0.878 (70.0/84.2). Note that the ROI (red cycle) should be drawn around the largest area of homogeneous echogenicity nodules. PTCs, papillary thyroid carcinomas; NGs, nodular goiters; UGSR, ultrasound gray scale ratio