Intralaryngeal application of a miniaturized ultrasonic probe

We developed a method for performing intralaryngeal ultrasonography. Normal larynges were obtained from 10 cadavers and examined using an intraluminal ultrasonic tomography apparatus connected to a radial scanning 20 MHz miniaturized probe. The larynx was placed in a bath filled with physiologic saline. and the probe was inserted through the forceps channel of the fiberscope (6 mm diameter). A horizontal ultrasonic image of the vocal fold was obtained. Histologic sections of the larynx were compared with the ultrasonic images. The mucosa in the membranous region of the vocal fold was comprised of three layers ultrasonographically. The epithelium and superficial layer of the lamina propria were visualized as a high echo (hyperechoic) region, the intermediate layer of the lamina propria was visualized as a low echo (hypoechoic) region and the deep layer of the lamina propria was seen as a hyperechoic region. The vocal fold structure can be visualized by intralaryngeal ultrasonography using the filling method. This method may be clinically useful for the detection of tumors involving the vocal folds.