A false lumen is the space created between the layers of an arterial wall when blood dissects through a tear in the inner lining. In an aortic dissection, the false lumen runs alongside the true lumen, and the two are separated by an intimal flap, a thin membrane of torn tissue. On ultrasound, the false lumen can sometimes be identified by its different flow patterns on color Doppler, as blood in the false lumen often flows more slowly, in a different direction, or with a swirling pattern compared to the true lumen. Distinguishing the true from false lumen is important because treatments are directed at maintaining blood flow through the true lumen while managing or sealing the false lumen.
Sonography Term