Figure 10b. Paravertebral approach for biopsy of a subcarinal mass. (a) CT scan shows a subcarinal mass (M); an 18-gauge needle has been advanced to the edge of the paravertebral space (arrowhead). (b) CT scan shows that injection of saline solution through the guide needle (arrow) has widened the mediastinum (arrowhead), creating a safe extrapleural path to the mass (M). (c) CT scan shows a 22-gauge needle (arrowhead) advanced through the 18-gauge needle (arrow) for biopsy of the mass (M).