Composite 2D-mode image and M-mode image of a small pleural effusion Composite 2D-mode image and M-mode image of a small pleural effusion. The 2D-mode image shows the cursor placement across the chest wall and an anechoic area between the chest wall and lung air artifact. The M-mode image demonstrates respirophasic movement of the lung toward the chest wall, called the "sinusoid sign," confirming the presence of pleural fluid. Source: Chapter 7. Thoracic Ultrasound, Handbook of Critical Care and Emergency Ultrasound Citation: Carmody KA, Moore CL, Feller-Kopman D. Handbook of Critical Care and Emergency Ultrasound; 2011 Available at: https://accessanesthesiology.mhmedical.com/DownloadImage.aspx?image=/data/books/carm1/carm1_c007f006.png&sec=41067266&BookID=517&ChapterSecID=41066793&imagename= Accessed: December 27, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved