Figure 15a. Transsternal approach. (a) CT scan shows an 18-gauge needle (arrow) traversing the sternum and a 20-gauge core biopsy needle (arrowhead), which was advanced through the 18-gauge needle into an anterior mediastinal mass (M). (b) CT scan shows an 18-gauge biopsy needle (arrow) advanced through the sternum into an aortopulmonary window mass (M). A = ascending aorta, PA = pulmonary artery. (c) CT scan shows transsternal biopsy of a pretracheal mass (M) with an inner 22-gauge biopsy needle (arrow) passing between the superior vena cava (V) and aortic arch (A).