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PERFUSE Quantitative Angiogenesis Techniques |
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Click here to go to an overview of Qualitative Angiogenesis Techniques
Quantitative
Angiographic Analysis: The PERFUSE
Collateral Frame Count The PERFUSE Collateral Frame Count is the number of frames required for contrast media to reach the recipient vessel. It is an index of coronary flow and is essentially a measure of the time for dye to travel down an epicardial artery to arrive at the recipient artery. Given that it is difficult to define precisely where a collateral vessel begins, and where the parent vessels ends, the beginning of the parent vessel is used for frame counting. The first frame is that frame in which dye extends across at least 70% of either the left main, the right coronary artery, the saphenous vein graft or the left internal mammary artery. Dye may leak from the catheter prior to injection and track down a single wall of the artery, but these frames are not included in the Collateral Frame Count. In the infrequent event that the left anterior descending artery is subselectively engaged and the left circumflex artery is the culprit vessel, the Collateral Frame Count begins when dye first touches both borders at the origin of the left circumflex artery. The last frame counted is the frame in which dye first enters the recipient epicardial artery; complete opacification of the recipient artery is not required, only initial entry of dye into the recipient artery. Often the last frame is more easily determined by running the film past the initial opacification of the recipient vessel and then moving frame-by-frame in reverse order until the recipient disappears. The last frame would then be the very next frame at which the recipient vessel reappears. How do I pick the first frame in the PERFUSE Collateral Frame Count ? In frame zero, dye touches either none of the borders or only one of the borders as shown below:
We find that in some injections dye will dribble down on border of the
artery and these frames are not selected as the first
frame. In frame number one, dye extends across at least 70% of the artery and moves forward as shown below:
How do I pick the last frame in the PERFUSE Collateral Frame Count? In the last frame, the dye first enters the distal landmark. This frame is included in the frame count. Quantitative Angiography: Validated automated edge detection is used to quantitate the stenosis severity of lesions that appear to be more than a luminal irregularity (i.e. >20% stenosis by visual inspection). Likewise, if there is one film in which the percent diameter stenosis exceeds 20% (and the other film is <20%), than both films undergo QCA analysis. If a lesion is present in one film that exceeds the percent stenosis by over 20% in comparison to the other film, then a “new lesion” will be said to have developed. The single plane projection showing each lesion in its tightest view is analyzed at the time of initial and repeat angiography. The minimum lumen diameter, the proximal reference segment diameter, and the percent stenosis are assessed. If the proximal reference segment is not available, then the distal normal reference segment diameter is used instead. Measurement
of Changes in Blush Size
at the PERFUSE Core Laboratories: The blush size increases progressively through each cardiac cycle. The following procedures are used to determine this change in blush size. 1. Determine the first frame in which dye fully enters the artery, marked by dye touching both borders of the left main or right coronary artery. (This is the same procedure as is used for the TIMI Frame Count Method.) Dye may initially track down a single wall of the artery as dye leaks from the catheter prior to the injection and these frames are not included in the TIMI frame count. In the infrequent situation in which the left anterior descending artery is subselectively engaged and the left circumflex artery is the culprit vessel, the TIMI frame count begins (frame one) when dye first touches both borders at the origin of the left circumflex artery. 2. Record the frame count at end diastole of the first cardiac cycle following frame one. (This is the beginning of cardiac cycle number one.) Planimeter the circumference of the blush at this point if blush is present. Determine visually if blush is apparent at end systole of this first cardiac cycle. 3. Record the calipered (mm) and the known manufactured french size of the catheter. 4. Record the frame in which blush first appears. 5. Repeat step two for as many cardiac cycles as possible. (NOTE: Frame one, determined according to the TIMI Frame Count Method, is only found initially, not every time blush is measured at end diastole.) 6. Calculate the total number of frames elapsed by subtracting the frame count at the time when blush first appeared from the final frame count. (NOTE: The frame count at the first appearance of blush may not be during the first cardiac cycle.) Calculate and record the percent of the cardiac cycles in which systolic blush was visually apparent (%systolic blush). 7. Using the total number of frames elapsed, the change in blush size in one film can be compared to others by calibrating the frame counts. (This is assuming all films are recorded using the same field size and a minimum of three cardiac cycles can be analyzed.) Click here to go to an overview of Qualitative Angiogenesis Techniques
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