Ultrasound elastography (USE).

A: Sagittal USE image of the tongue. The elastography measurement region is shown with color overlay in the top image. The dark region on the right side of the image is due to shadowing from the hyoid bone. B: Colorized ROI with scale bar converting color to stiffness value (kPa); C: Circular ROI from the center of the USE color region. D: The stiffness measurement according to the color scale in B for the extracted circular ROI. r: rostral, c: caudal; v: ventral; d: dorsal.