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UVMFLOWNET  March 2003

UVMFLOWNET March 2003

Subject:

Re: Mesenterics

From:

Cindy Owen <[log in to unmask]>

Reply-To:

UVM Flownet <[log in to unmask]>

Date:

Wed, 19 Mar 2003 09:08:40 -0600

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (157 lines)

Hi Neil,

The maximum Doppler PRF that you can obtain is determined by the system
manufacturer (some systems have much higher pulsed wave PRF's than others).
But for any given system,  the maximum PRF that it can obtain is determined
by depth. In general, the shorter the distance to the sample volume, the
higher the PRF that can be obtained (you may notice that the PRF changes as
you move the sample volume up and down- as you increase SV depth the PRF
will go down but may jump back up at certain depths). If you are using
triplex (live color and Doppler) the maximum PRF may also be reduced (this
is only true for some systems). By using a lower frequency Doppler, you can
reduce the frequency shift for any given velocity. This would allow you to
show higher velocities at the same PRF without aliasing.

So, to maximize the velocities seen without aliasing, try the following-
    - if your system cannot obtain its' maximum PRF during triplex, turn
triplex off (instead, use an update mode to "toggle" between Doppler and
color)
    - use the lowest Doppler frequency to reduce the frequency shift from
the flow
    - minimize depth to the vessel of interest (change your acoustic
window/approach or push in a bit more)

When shopping for new equipment, the maximum PRF attainable is one important
thing to evaluate. Many systems are limited to about 18- 21 kHz, whereas
other systems have PRF's up to 30 kHz. Remember to try the Doppler at
different depths, triplex on and off. Having higher PRF's makes it easier to
get the information needed when you have high velocities.

Hope this helps,
Cindy Owen

----- Original Message -----
From: "Neil" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, March 18, 2003 7:34 PM
Subject: Re: Mesenterics


> We have been having a problem getting started on these.  One of my
> coworkers complained that on both the Acuson 128s and the ATL UM9s he
> is getting an error when trying to spectral doppler deep in the
> abdomen.  (And all he gets is aliasing)  The message is something about
> high PRF.  Any tips on how you can get a higher PRF, deep?  I'm not
> sure what he is doing wrong... (or not doing right)
>
> Thanks for any basic tips,
>
> ...Neil
>
>
> On Tuesday, February 18, 2003, at 12:23  PM, Johnson, Bonnie L. wrote:
>
> > Zwolack's group also did a paper on using the end diastolic velocitiy
> > (EDV)
> >> 45cm/s as the primary indicator for dz greater than 50% rather than
> >> using
> > the PSV alone.  We use this and it is very helpful.  A preprandial SMA
> > of
> > 300cm/s PSV with an EDV below 45cm/s is considered <50%.
> >
> > Zwolak R, Fillinger M, Walsh D, et al: Mesenteric and celiac duplex
> > scanning: a validation study. J Vasc Surg 1998;27:1078-88.
> >
> > bj
> >
> > Bonnie L. Johnson RDMS, RVT, FSVT
> > Stanford University Medical Center
> > Director, Vascular Laboratory Services
> > Division of Vascular Surgery
> > Stanford, CA
> >
> >
> >
> > -----Original Message-----
> > From: Brian Hembling [mailto:[log in to unmask]]
> > Sent: Monday, February 17, 2003 7:34 PM
> > To: [log in to unmask]
> > Subject: Re: Mesenterics
> >
> >
> > Shelly
> >
> > In reference to celiac arteries, we had a similar problem with
> > "over-calling. "
> >
> > We did a search for literature and found a couple articles by Zwolak
> > that
> > referenced retrograde flow in the common hepatic artery as a hallmark
> > of
> > severe celiac stenosis.
> >
> > Our own internal validation confirmed that anytime we have a retrograde
> > common hepatic artery, we have a >80% stenosis or an occlusion.
> >
> > Articles below:
> >
> > Can duplex ultrasound replace arteriography in screening for mesenteric
> > ischemia?
> > Semin Vasc Surg. 1999 Dec;12(4):252-60. Review.
> >
> > Mesenteric and celiac duplex scanning: a validation study.
> > J Vasc Surg. 1998 Jun;27(6):1078-87; discussion 1088
> >
> > -Brian
> > __________________________________________
> > Brian P. Hembling, BS, RVT
> > Technical Director
> > Baptist Vascular Center of San Antonio
> >
> > ----- Original Message -----
> > From: Shelly Burns <mailto:[log in to unmask]>
> > To: [log in to unmask] <mailto:[log in to unmask]>
> > Sent: Monday, February 17, 2003 6:33 PM
> > Subject: Mesenterics
> >
> > Another question.  I did correlations for 2002 and we are missing on
> > the SMA
> > and Celiac arteries.  The published information we have states
> > velocities of
> > 220 and greater than 240, something like that.  We find velocities in
> > the
> > 300's with what appears to be turbulence in the doppler signal and the
> > angio
> > says it is normal.  Does anyone have new criteria?  We just don't want
> > to
> > call these anymore.  At least with renals there is a ratio to assist.
> > Imaging of the celiac axis and SMA is either very good or lousy.
> > Speaking of renals, a patient today had RRA velocities of 130 to 190
> > to 230
> > with no obvious turbulence and ratio of 2.5.  The LRA velocities were
> > 70 to
> > 100.  Could she have a 50% stenosis on the right?  Is there any new
> > velocity
> > info or parameters on renal arteries?  Who is doing the research out
> > there????
> > Thanks.
> >
> > Shelly Burns
> > Summa Health System
> > Akron, OH
> >
> > Shelly Burns
> > Summa Health System
> > Akron, OH
> >
> > To unsubscribe or search other topics on UVM Flownet link to:
> > http://list.uvm.edu/archives/uvmflownet.html
> >
>
> To unsubscribe or search other topics on UVM Flownet link to:
> http://list.uvm.edu/archives/uvmflownet.html
>

To unsubscribe or search other topics on UVM Flownet link to:
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