Ultrasound imaging of popliteal vein thrombosis

This is a rather puzzling case. 54 year old male patient with right calf pain.
The right femoral vein shows this highly pulsatile nature (observe those spectral Doppler waveforms).
Perhaps they can be explained by the transmitted pulsations of the adjacent femoral artery. But I am not fully convinced. Those pulsations were seen even in the GSV (great saphenous vein). See images below:
The right femoral artery:

The right GSV (great saphenous vein): There is no normal venous flow pattern- only a spiky pulsation- more arterial in nature:

The right femoral vein:

Normal compressibility of the right femoral vein:

The femoral vein and artery in long section color Doppler flow:

Spectral Doppler trace of the right femoral vein- again that pattern

I tried augmentation by compressing below the calf- weak augmentation of the femoral vein:

And now the right popliteal vein:
The upper half of the popliteal vein shows good flow on color Doppler imaging:

Spectral waveform- normal flow in upper part of popliteal vein:

Strong venous waveforms again in the upper half of the popliteal vein:

The lower half of the popliteal vein shows a different picture with a partial thrombosis likely. There is almost no flow in this part of the vein. The thrombosis of the popliteal vein can explain the calf pain.

 Comparing the upper half and lower part of the affected popliteal vein- normal flow in the upper half vs poor or no flow in the lower part. That echogenic matter in the lower part is possibly the thrombus!