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Re: "trophotropism" theory of placental migration, etc.From: Terry J. DuBose (tjdubose@juno.com)Wed Dec 3 00:30:37 1997
Rocky, If I remember correctly, we corresponded about a year ago... may be longer? Correct? Are you the guy who builds some specialized, very high frequency transducers? Any way, as to your questions. Yes the "trophotropism" study regarding the relative placement of the umbilical cord insertion is just a matter of statistics. However, it will take a very large population with longitudinal data to catch a relatively few placentas the appear to "migrate" in order to document that the relative cord insertion "moves" closer to one edge as the placenta morphs toward rich blood supply and away from lesser perfusion. That is a bit more of a study than I am in a position to undertake, right now, in this place. I hope this brief explanation is clear, that is how Harris Finberg thought it could be done. Bill Johnson suggested that "Power" Doppler might be a better approach. And as I think about it, he may be correct. Power Doppler, sometimes called "Angio" Doppler was first developed by Diasonics around 1990 (I think). It is not used to tell direction of flow, but only looks at the amplitude of the Doppler shifted waves. It is very sensitive to very low flow states, but, as I said, doesn't provide flow information. ACUSON has overlaid conventional Doppler directional flow so they kind of get the advantages of both. "Power" Doppler doesn't have anything to do with the amount of energy put out, but the amplitude of the Doppler shifted echoes only, but not the direction. Only the amplitude. A better designation might be "Amplitude" Doppler. That is about as far into the physics of it that I can go into here. But it does seem that looking at the relative perfusion using "Power" Doppler might allow one to select which placentas might be in a state of trophotropism due to the discordant perfusion across the sub-placental area. I don't know for sure but it might be possible. May be some bright young researcher will latch on to this. We all would learn something. Hope this helps. And hope you don't mind if I send this out to the list. Want to keep the chatter up, especially on topic. Peace, Terry J. DuBose
On Tue, 2 Dec 1997 11:05:44 -0800 rocky <rocky@xdcr.com> writes:
>Terry -
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