Shades of Grey
ANSWER: The Curtain Sign.
This is created by a fully expanded lung, covering the lateral aspect of the diaphragm as the person breathes, much likened to a curtain being drawn back and forth. When demonstrated at the most dependent part of the lower chest, a pleural effusion or pathology at the lateral lung base can be excluded.
Dr. Francis Lee Chun Yue
Acute and Emergency Care Centre, Khoo Teck Puat Hospital. Singapore