Dear Ruth,

The question of how to classify carotid stenosis has been vexing us since 
Egaz Moniz.
Unfortunately, Anatomy/Velocity Correlation is futile, in spite of our 
confidence to the contrary.
Beach KW, Leotta DF, Zierler RE., Carotid Doppler velocity measurements 
and anatomic stenosis: correlation is futile., Vasc Endovascular Surg. 
2012 Aug;46(6):466-74.

from the Ultrasound Reading Center and the D.E. Strandness Jr. Vascular 
Laboratory at University of Washington Medical Center, University of 
Washington, Seattle, WA 98195, USA.

BACKGROUND: Duplex ultrasound with Doppler velocimetry is widely used to 
evaluate the presence and severity of internal carotid artery stenosis; 
however, a variety of velocity criteria are currently being applied to 
classify stenosis severity. The purpose of this study is to compare 
published Doppler velocity measurements to the severity of internal 
carotid artery stenosis as assessed by x-ray angiography in order to 
clarify the relationship between these 2 widely used approaches to assess 
carotid artery disease.

METHODS: Scatter diagrams or "scattergrams" of correlations between 
Doppler velocity measurements and stenosis severity as assessed by x-ray 
contrast angiography were obtained from published articles for native and 
stented internal carotid arteries. The scattergrams were graphically 
digitized, combined, and segmented into categories bounded by 50% and 70% 
diameter reduction. These data were combined and divided into 3 sets 
representing different velocity parameters: (1) peak systolic velocity, 
(2) end-diastolic velocity, and (3) the internal carotid artery to common 
carotid artery peak systolic velocity ratio. The horizontal axis of each 
scattergram was transformed to form a cumulative distribution function, 
and thresholds were established for the stenosis categories to assess data 

RESULTS: Nineteen publications with 22 data sets were identified and 
included in this analysis. Wide variability was apparent between all 3 
velocity parameters and angiographic percent stenosis. The optimal peak 
systolic velocity thresholds for stenosis in stented carotid arteries were 
higher than those for native carotid arteries. Within each category of 
stenosis, the variability of all 3 velocity parameters was significantly 
lower in stented arteries than in native arteries.

CONCLUSION: Although Doppler velocity criteria have been successfully used 
to classify the severity of stenosis in both native and stented carotid 
arteries, the relationship to angiographic stenosis contains significant 
variability. This analysis of published studies suggests that further 
refinements in Doppler velocity criteria will not lead to improved 
correlation with carotid stenosis as demonstrated by angiography.

On Tue, 9 Oct 2012, Matthew Smith wrote:

> i've seen the diastolic velocities and ICA/CCA ratio disregarded by reading docs in cases of moderate stenosis, while being viewed as more
> important in determining cases of severe stenosis (surgery is the point at which they have a hard, well-defined line). Clinically it makes
> sense, if a patient has "mild to moderate" plaque and a 45% stenosis they should probably be followed up regularly, just as someone with
> "moderate plaque" and a 51% stenosis.  They both have about a 50% stenosis.  Someone at the upper end of the 50-69% category would likely
> have no problem meeting the end diastolic criteria, you're talking about patients at the upper limit of mild stenosis being placed in the
> lower limits of the moderate category.  I doubt any imaging modality, in reality, is sensitive to a 6% difference in stenosis, it's all
> subject to measurement error, and ultimately someone's judgment call.   It may sometimes skew your QA correlations, but most of these
> patients wouldn't probably have additional imaging studies anyway, unless symptomatic or your study is suboptimal or its accuracy
> questioned.  if this is truly throwing off your accreditation/QA stats you should probably just ask the reading doc about their line of
> thinking (nicely of course).
> matt
> On Tue, Oct 9, 2012 at 10:20 AM, Kimberly Higgins <[log in to unmask]> wrote:
>       We have to meet BOTH peak systolic and end diastolic. Otherwise, why do you have the criteria written that way if you dont use
>       it?? ICAVL would probably question it. I have also discovered that your QA probably will not correlate.
>       ~Kim
>       ________________________________________
>       From: UVM Flownet [[log in to unmask]] On Behalf Of Deidre [[log in to unmask]]
>       Sent: Tuesday, October 09, 2012 11:39 AM
>       To: [log in to unmask]
>       Subject: Re: carotid correlations
>       At our lab we use 3 criterion and to put it in any category it must meet 2out of 3 of the criterion we established.  PSV EDV
>       AND RATIO
>       Sent from my LG phone
>       "Myers, Ruth" <[log in to unmask]> wrote:
>       >Hello flownetters-  I have a question about carotid correlations.  (Actually probably more about interpretation, but here
>       goes....)   If the systolic velocity meets the set criteria for a 50-69% stenosis, but the diastolic does not,  should it be
>       read based upon the systolic velocity alone?
>       >For example our criteria is 140 cm/sec systolic with 40 cm/sec diastolic = 50-69% stenosis.  However, my doc often reads
>       something that might be 142 cm/sec systolic but 25 cm/sec diastolic.  Am I okay to say that he has read correctly using the
>       diagnostic criteria when I am doing my correlations?
>       >
>       >Ruth Myers, BS, CNMT, RDMS, RVT
>       >Lead Technologist
>       >Vascular Laboratory
>       >Beebe Medical Center
>       >Lewes, Delaware
>       >
>       >
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