```Kevin,

Paul is correct.  From your original post, I assume you are talking a renal transplant in which case the typical velocities used for diagnosis of native renal arteries are not fully validated. You are correct, if you get 350 cm/sec at 0 degrees, than that should be pretty accurate.  However personally, I would never rely on a number. Did you have a focal velocity acceleration, find post stenotic turbulence, see a diminished systolic upstroke distally. If you see all of these findings, there is no doubt a stenosis. If not all of the above, and while 350 cm/sec would be highly suspicious, may be little better than flipping coin.

Regards,

Bill

William B Schroedter, BS, RVT, RPhS, FSVU

Technical Director

Quality Vascular Imaging, Inc

Venice, Florida

(941) 408-8855

<http://www.qualityvascular.com> www.qualityvascular.com

<http://www.compressionsocks.pro> www.compressionsocks.pro

Sent: Sunday, February 09, 2014 4:40 PM
Subject: Re: Doppler Physics Experts

Sent: Sunday, February 9, 2014 4:04 PM
Subject: Re: Doppler Physics Experts

Having a physics and mathematics background long before I ever heard about diagnostic ultrasound, let alone diagnostic Doppler ultrasound, I’ve always believed, clung to and taught my students that math is math and physics is physics.  If the path of insonation is going directly down the “gun barrel” of a vessel then the angle of insonation is 0 degrees so no angle is required.  If not then we use the angle correction to get a statistically correct velocity measurement.  The angle correction is kept between 0 and 60 degrees because the cosine of the angles in that range have smaller degree of statistical variant than the cosine of angles above 60.  This was the basis of Dr. Frederick Kremkau’s explanation of angle correction that I was fortunate to hear many, many years ago.

Sent: Sunday, February 09, 2014 1:40 PM
Subject: Re: Doppler Physics Experts

I hope your RI's were taken at the distal segmental arteries or arcuate arteries. If so, then this measurement is taken without any angle correction and an RI of 0.9 is definitely abnormal. Most facilities us any RI  of  0.8 or above as abnormal. If this is the case then it doesn't matter what the renal artery showed, the RI's would still be considered elevated and abnormal.

A zero degree angle is used in Echo but not really in abdominal imaging. Most criteria is based on angels between 45 and 60 degrees. If your facility has written protocols then the acceptable angels should be in writing.

Sent: Sunday, February 9, 2014 1:52 PM
Subject: Doppler Physics Experts

For the experts:
I had a new renal tx patient ( difficult exam due to body habitus) with elvated velocities in the distal MRA in the >-350cm/sec range utilizing a 0 degree angle as it was felt to obtain the optimal velocity. There were very high resistive indeces in the .9 range. The Radiologist felt that this was not significant and called a normal exam with suboptimal doppler angle. When we discussed this he felt that the 60 deg angle was optimal for the abdominal vasculature and that the normal velocity ranges were based on this angle utilizing cos 60deg being .5 . He felt that the velocities obtained were actually half due to the 0 deg angle.

I always thought that the formulas installed in the machines compensated to obtain the true velocities? So I went back and obtained velocities at 0, 50, and 60 degree angles. All velocities were over 350cm/sec.

Thanks in advance to any insight into this.

Kevin

> Date: Fri, 7 Feb 2014 19:01:51 +0000
> Subject: Re: 93978 or 93979
>
> 93978
>
> -----Original Message-----
> Sent: Friday, February 07, 2014 12:50 PM
> Subject: 93978 or 93979
>
>
> For an Endovascular protocol that includes the following:
> Gray scale and/or CD imaging of the Native Aorta, residual sac diameter, limbs of the graft, native outflow, iliacs and CFA PSV measurements in the Native Aorta, Proximal Graft, Right Limb, Left Limb, Native outflow, EIA and CFA
>
> Which CPT code are you most comfortable with 93978 or 93979?
>
> Thanks,
> Nancy
>
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```