Hi Linh,
I agree, they can be really easy and beautiful or really difficult!
I will answer your questions.
1: Yes, I think beam steering is overused and more beam steering should only be used when I can not heel and toe the transducer to keep my angle below 60 degrees.
In the carotid system anything less than 60 degrees is OK but I think if you are using more beam steering to get a lower angle you are creating a linger tissue path for the beam and the signal to noise ratio and the sensitivity will suffer. So a balanced approach using minimal beam steering, heel and toe technique and keeping your angle less than 60 degrees is the correct approach. Like many things in life a balanced approach is best.
Yes there is some evidence the modern stations with other lifestyle changes etc can reduce plaque slightly over time.
2: Personally I don’t use these functions as I like to adjust things myself, however they do work fairly well on the current machines and it is a nice short cut if you want to use it.
3: Colour frequency and also frequency in pulse wave are really great things to adjust. I commonly adjust them for all Doppler work and it makes a huge difference. Same principles apply as your b-mode image, if it is superficial (CCA on a skinny neck) use a higher frequency then drop it down for the vertebral as it is deeper.
I don’t use Power Doppler much at all to be honest. you can use it to delineates oft plaque but be careful with Power Doppler as it blooms and overwrites the plaque easily. I think there are better options to Power Doppler. Try SMI, ADF, B-Flow etc.
4: Yes the beam steering should be adjusted and optimised as you work your way through a tortuous vessel.
5: Yes, young patients can have this hyper dynamic circulation and if you use the 2:1 PSV ratio as a guide you will see there is no stenosis.
6: Yes this is normal. The vertebral artery can stay outside the expected location between the transverse processes and then dive down. You see this fairly commonly . Also the vertebral artery is a great example of where less beam steering is really important and a low Doppler frequency in both colour and pulse wave is a great trick, especially on a thick bull neck.
Steve