Abstract
In radiological intravascular interventional we often need to know sizes of arteries from angiograms. For carotid stenting, we need to know information about the width and length of stent to be used. For aneurysm embolization, this information is necessary for us to decide the size of coil. We study the distortion and magnification ratio in different locations of the angiogram.
We replace the anti-scatter grid with a grid plate with 1 cm markers inside on the lateral arm of the angiogram. We took lateral projection with 4 modes (12, 9, 6, and 4.5 inches) separately, keeping a constant distance of 135cm between the tube and the image intensifier, and holding the C-arm of the lateral projection horizontally. Then we measured the pixel size of a 2cm length grid in vertical and horizontal orientations in different parts of the angiogram. We did each measurement for 3 times for calculation of intra-observer reliability.
We found the distortion and magnification are most obvious on peripheral portion of the image. The magnification ratio may increase up to 1.41 times at the periphery of the image. The distortion and magnification are because of pincushion distortion and S distortion.
When the site of the artery to be measured and the ruler are in different locations of the angiographic image, we have to consider the distortion and variation in magnification ratio when we measure the width and length of the artery.
We replace the anti-scatter grid with a grid plate with 1 cm markers inside on the lateral arm of the angiogram. We took lateral projection with 4 modes (12, 9, 6, and 4.5 inches) separately, keeping a constant distance of 135cm between the tube and the image intensifier, and holding the C-arm of the lateral projection horizontally. Then we measured the pixel size of a 2cm length grid in vertical and horizontal orientations in different parts of the angiogram. We did each measurement for 3 times for calculation of intra-observer reliability.
We found the distortion and magnification are most obvious on peripheral portion of the image. The magnification ratio may increase up to 1.41 times at the periphery of the image. The distortion and magnification are because of pincushion distortion and S distortion.
When the site of the artery to be measured and the ruler are in different locations of the angiographic image, we have to consider the distortion and variation in magnification ratio when we measure the width and length of the artery.
Translated title of the contribution | Image Distortion on Digital Subtraction Angiography and Its Impact on Measuring Sizes of Blood Vessel |
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Original language | Chinese (Traditional) |
Pages (from-to) | 95-101 |
Journal | 中華放射線醫學雜誌 |
Volume | 30 |
Issue number | 2 |
State | Published - May 2005 |