Case 12 Answer

Answer: anterior junction line - ie a line made up of the combination of the left and right visceral AND parietal pleura (so 4 pleura).

The posterior junction line can sometimes be seen as well, however it is usually more cranial in location due to the posterior lungs extending more cranially. Thus, the anterior line shouldn’t extend cranial to the manubrium.

reference: http://radiopaedia.org/articles/anterior-junction-line