Fig. 3. Computed tomography aspect demonstrating the intraparenchymal route of a chest tube. On axial computed tomography sections, the chest tube is visualized from its entry in the left hemithorax ( image 1 , gray arrow ) to its extremity ( image 4 , thick black arrow ), via its posterior ( image 2 ) and descending intrathoracic route ( image 3 , gray arrowhead ). The presence of the left fissure at the vicinity of the tube ( image 2 , thin black arrow ) raises the possibility of an intrafissural position. Sagittal reconstructions clearly demonstrate the intraparenchymal position of the chest tube: Plane A shows the entry of the chest tube in the left upper lobe ( gray arrow ); plane B shows the intraparenchymal route of the chest tube, passing from the upper to the lower lobe through the left fissure ( thin black arrow ); plane C shows the entry of the chest tube in the posterior pleural space ( gray arrowhead ); and plane D shows the chest tube descending into the posterior pleural space ( thick black arrow ).