Figure 1From: Real-time ultrasound-guided percutaneous dilatational tracheostomy: a feasibility studyAxial images of trachea and pretracheal structures on ultrasound. Asterisk: Tracheal lumen. (a) Arrow- acoustic shadow of cricoid cartilage. (b) Arrow- acoustic shadow of first tracheal ring. (c) Arrow: Anterior tracheal wall between first and second tracheal rings. Arrowhead- Thyroid isthmus.Back to article page