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You are correct Joshua. But.... all the other imaging modalities also obtain 2D data - they simply construct 3D as do we. US has typically significantly higher resolution than does angiography, CTA, or MRA. Additionally, those modalities have limitations on the # of slices the use to create the image while we have virtually infinite #'s of slices as we scan through the area of interest. While our instrument generated 3D reconstruction is marginal at best (at this point in time), our mental 3D reconstruction is superb. As Bill Johnson notes, the key is physiology which creates a synergy with the imaging. We would NEVER call a stenosis based on velocity alone. But I do strongly agree with you, standardization and especially consistency is obtaining the data is critical. If you search back in the Flownet archives from about a year ago or so, you will find a post by Dr. Kirk Beach regarding reproducibility. To summarize his post (and correct me if I am wrong Dr Beach) Comparing a series of 20 Doppler vs Angiography publications, angiography and Doppler velocity had the following disagreement rate: Systolic Velocity 32% Diastolic velocity 33% ICA/CCA ratio 33% in native arteries. For stented arteries, disagreement was 20%, 30% and 30%. Comparative repeat ultrasound measurements disagreement : 7% on systolic velocity 11% on ICA/CCA ratio In summary - Ultrasound - 7% disagreement using PSV Angiography - 24% disagreement between readers The take home, US is significantly more reproducible than is angiography. Bill William B Schroedter, BS, RVT, RPhS, FSVU Technical Director, Quality Vascular Imaging, Inc 4120 Woodmere Park Blvd Suite 8B Venice, Florida 34293 (941) 408-8855 office [log in to unmask] -----Original Message----- From: UVM Flownet [mailto:[log in to unmask]] On Behalf Of Joshua Waks Sent: Thursday, October 18, 2012 1:02 PM To: [log in to unmask] Subject: Re: CCA criteria High quality duplex scanning is exceedingly important; however, there's too many variables and controversy. Intra-observer variability will always create a difference, but if you're looking at a stenosis of >70%, where do you align the sample volume to? Vessel wall or flow jet? If it's aligned to the flow jet, the transducer being at a slightly different approach, the tech will view a slightly different jet, and get a different velocity, because we're viewing a 3- dimensional object in 2 dimensions. GREATER STANDARDIZATION IS NEEDED. I know this, and I just graduated from my Vascular Tech program! 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