Don't know if you'll still get this, it was posted so long ago, but I have the same thing and I used to be a vascular sonographer who did the duplex scans.
In and of itself, a tortuous ICA is not as concerning as if there were plaque in the ICA which could break off and cause a stroke. My guess is that you have a tortuosity (and not a kink) without significant plaque, and that's why your docs are not all that concerned.
Headaches would be unlikely, the symptoms you would need to look out for are right sided weakness or numbness &/or difficulty in speaking &/or a left eye visual disturbance.
With regard to the 'whooshing': that is the sound of your blood at a high velocity or turbulence. Think about when you curl a garden hose, the water has a more difficult time flowing through and will either get stuck and swish around (turbulence) or it will whoosh through at a higher velocity, like holding your thumb over it. This is as opposed to kinking a garden hose which can *stop* the blood flow. If your docs are not concerned, most-likely you don't have a kink. And even if the doppler tech was not very good, they would pick it up on the MRA most-likely.
I'm beginning to figure for myself that I'm just going to have to live with this sound in my ear like yours. (It's called a 'bruit' - the 't' is silent.)
The question to ask yourself is how long have you had it. Is it congenital or has it developed? If it has developed, then you want to make sure that you are keeping your blood pressure down (well, you want to do that anyway, but that is one cause for such an anomaly.)
Hope things are going well for you and I hope this helps.
Could a tortuous artery within normal limits and all other indicators within normal limits, except an ICA 50-69@ stenosis reading on the doppler (not on the image) be caused by the blood hitting a twist in the artery and not necessarily from plaque? Or could there be a false positive if the tech is taking the curve of the twist too closely?
BTW, the Impression states: tortuous ICA without significant disease by image with velocities suggestive of a 50-69% diameter stenosis.