Cystic adventitial disease
Cystic disease of the adventitia is more frequent in males and predominantly affects the popliteal artery, although it can affect other arteries. The cysts contain a proteinaceous or mucinous fluid, and surround the artery. They can generate extrinsic compression of the arterial lumen, especially during exercise, which is why they produce claudication. At rest, they do not usually give symptoms. Within the possible etiologies, trauma of the artery wall is considered the most probable.
Ultrasound is a very good method for the examination of the painful knee and to rule out other differential diagnoses such as Baker cyst or deep vein thrombosis. The cysts are observed as periarterial anechoic images, which do not show flow with color or power Doppler.
With Doppler ultrasound, dynamic maneuvers can be performed and the compression of the lumen can be demonstrated with muscle contraction.
On MRI, the cysts are hyperintense on T2, and are usually hypointense on T1 although this depends on the mucin or protein content.