Fig. 3. Risk classification of recurrent laryngeal nerve and tracheal invasion. Presence (A) and absence (B) of a normal rim between the tumor and the course of the RLN; Protrusion(C) is defined as the outward bulging of the contour by the tumor beyond the expected normal thyroid margin; Angles between the tumor and the tracheal wall. Obtuse angle(D); Acute angle(E); Right angle(F).

J Surg Ultrasound 2024;11:18-24 https://doi.org/10.46268/jsu.2024.11.1.18

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