Are there ways to see my blood flow and position of veins / arteries after rhinoplasty? Hoping to have a liquid rhinoplasty done

There is no way to view the veins and arteries in the nasal area in a typical clinic setup. While there are some injectors that will utilize ultrasound in parts of the face to identify vessels prior to injecting, this is not standard practice. A good, trained injector will follow the patterns of injection that reliably allow him or her to avoid known anatomic problem areas. This, along with the techniques that you previously mentioned, will allow for a safe injection practice.

You are right to be concerned about liquid rhinoplasty after previous rhinoplasty surgery. Make sure you are being treated by a board certified plastic surgeon. Vascular compromise is a major complication of liquid rhinoplasty, but is more common after a surgical rhinoplasty. This is likely due to fibrosis and scarring that creates a much more confined space for filler to go and higher pressure gradients with injection. I have seen blanching after injecting 0.1 cc of fat / filler product in this patient population and have seen presentations given on this topic at national meetings (Dr Jamil Ahmad gives an excellent talk on this topic for plastic surgeons).The injector must be experienced in dealing complications and so please do your research and proceed with caution. In terms of vascular mapping, there are techniques for mapping vasculature but I do know of anyone that has tried this in the setting of liquid rhinoplasty. It might be a good idea though as this technology does exist. Even if you had it in your case, I do not think it will appreciably decrease your risk of vascular compromise. Instead make sure the surgeon that you choose has experience with this procedure, and goes very slow with low volume injections.