Great video! I have one more question: now it's clear how to interpret the flow direction when the probe is parallel to the vessel. It's not very clear to me how to interpret the direction when the probe is sagittal (the vessel is a circle). Thanks!!
The short simple answer is: You don't.(Creds to my teacher) The longer answer, as of my current understanding, is that you end up not having a true known reference in relation to the vessels direction, hence nothing to compare to give meaningful data for the direction of flow along the vessel. It is maybe even more simple to just draw the vessels in longitudinal and sagittal and draw the lines. Then you realise that in sagittal you do not get the colour flow up or down the vessel(along the vessel) but the vector from left to right inside a short section of the vessel, (from wall to wall). There is no proper way to determine the angle in that plane to give meaningful direction along the vessel since you do not know the vessels direction from that single section. Even if you determine the flow in that short section it does not say anything about the direction up or down the vessel. Just left to right or right to left. I found it very difficult to wrap my head around this too and there is pretty much no explanation anywhere on the internet so I did some own testing from my understanding and I came to the conclusion that I could only tell if blood flows left or right in the short section, and not up or down. (If I am wrong I would gladly have someone explain it) In real practice it does not matter in some situations since it is good enough to quickly do some overview scans before acurate messurments but for determining flow direction and proper flow it gets confusing since we end up with the wrong vector.
Many thanks for a nice lecture.
Nice explanation. Thanks!
Great video! I have one more question: now it's clear how to interpret the flow direction when the probe is parallel to the vessel. It's not very clear to me how to interpret the direction when the probe is sagittal (the vessel is a circle). Thanks!!
The short simple answer is: You don't.(Creds to my teacher) The longer answer, as of my current understanding, is that you end up not having a true known reference in relation to the vessels direction, hence nothing to compare to give meaningful data for the direction of flow along the vessel.
It is maybe even more simple to just draw the vessels in longitudinal and sagittal and draw the lines.
Then you realise that in sagittal you do not get the colour flow up or down the vessel(along the vessel) but the vector from left to right inside a short section of the vessel, (from wall to wall). There is no proper way to determine the angle in that plane to give meaningful direction along the vessel since you do not know the vessels direction from that single section. Even if you determine the flow in that short section it does not say anything about the direction up or down the vessel. Just left to right or right to left.
I found it very difficult to wrap my head around this too and there is pretty much no explanation anywhere on the internet so I did some own testing from my understanding and I came to the conclusion that I could only tell if blood flows left or right in the short section, and not up or down. (If I am wrong I would gladly have someone explain it)
In real practice it does not matter in some situations since it is good enough to quickly do some overview scans before acurate messurments but for determining flow direction and proper flow it gets confusing since we end up with the wrong vector.