This was a 45-year old man with severe proteinuria. Color Doppler US of the left renal vein (LRV) in transverse plane shows severe compression between abdominal aorta and superior mesenteric artery and bright-colored jetting flow in the inferior vena cava. Measured peak flow velocity was approximately 3 meters per second which is much higher than normal velocity of 40 to 50 cm/sec. 
[Prof. Seung Hyup Kim, Professor in Radiology and Urology, Seoul National University, Korea]

Diagnosis

Nutcracker Syndrome