off-centre and kinked/sinuous [vascular] lumen
A different interpretation!
a representation of a different property of blood flow, PD has several advantages over CD; it has greater sensitivity to detect the blood flow itself and, with the same angle of insonation, PD images permit better definition of the intravascular surfaces and visualization of continuity of flow than CD ones. In other words, PD images are independent from the angle of insonation . This is particularly useful in arterial stenosis, since PD imaging results in an angiography-like visualization of the whole vascular lumen [22,23]. Indeed, PD permits to clearly represent in color the low-velocity post-stenotic flow. This could be even possible with broad band CD flow, keeping PRF as low as possible; with such a modification of PRF, yet, the aliasing phenomenon would lose its significance and the frame rate would be extremely low. Moreover, PD improves the visibility of vessels that are sinuous or kinked or lying on a plane perpendicular to the ultrasonic beam, due to its independence from the angle of insonation. Yet, PD disadvantages mainly consist in long scanning time that makes PD images susceptible to soft-tissue flash artifacts and movement artifacts; moreover, PD does not yield directional or velocity information and, consequently, does not permit to detect aliasing, although it gives the operator the possibility to place the PW sample volume at the most stenotic tract of the vessel. Finally, the frame rate is much lower with PD than with CD, so that arteries are not distinguished from veins on the basis of their color pulsatility. Accordingly, PD is a useful tool, but it is complementary to Duplex/CD in vascular sonography: they should be used together for optimal diagnostic results, CD and aliasing being the guides to PD activation.
Mechanical Analysis of Atherosclerotic Plaques Based on Optical ...
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to the visualization of the vascular lumen and does not. provide information regarding the ... both cases, this is the most kinked region of the lumen, nat- ...
www.ocf.berkeley.edu/~mctbl/ABME2004_OCT.pdf - Similar pages
High stresses are also found near
the 5 o’clock position due to the curvature of the region. In
both cases, this is the most kinked region of the lumen, nat-
urally leading to focal stress concentrations. Although the
maximum stress in the histology-based model is higher than
in the OCT case (985 vs. 343 kPa), its location corresponds
to a portion of the lumen that was folded in histology. This
geometry artifact causes an erroneously high focal stress
concentration in the histology-based model. If these arti-
factual maximum stress magnitudes are not considered, the
stress distributions are similar between the OCT and his-
tology models, a fact which is more easily appreciated by
examining the stress distribution on a sector by sector basis.
Estimated Flow Resistance Increase in a Spiral Human Coronary ...
In the side view, the vessel appears to have a pronounced kink in the curvature ... radius of spiral or coil = lumen cross-sectional area = pitch or axial ...
link.aip.org/link/?JBENDY/122/675/1 - Similar pages
| liz askew|
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