Improved Image Guidance for Coronary Stent Deployment

Tech ID: clo000020



Increasing numbers of percutaneous transluminal coronary angioplasty (PTCA) are being performed in the United States. However, after PTCA, restenosis of the dilated segment occurs in a large percentage of patients. PTCA followed by coronary stent placement provides a luminal scaffolding that has been shown to significantly reduce the likelihood of restenosis. In such procedures, cardiologists frequently deploy multiple adjacent stents in an artery to treat extended lesions or dissections. Since it is important to accurately align the stent ends, the cardiologist must adjust the position of the catheter head relative to a previously deployed stent. This requires that the first stent and the catheter head be visualized well enough that their relative stent positions can be accurately determined. This has not been possible in conventional coronary stent deployment techniques. As a result, a subsequently placed stent often cannot be placed precisely in relation to a previously placed stent, resulting in either an overlap or a gap between the two stents. Gaps between stents are significant because of the risk of residual dissections and restenosis. In addition, studies with intravascular ultrasounds (IVUS) imaging of deployed stents revealed that a high percentage of stents may be insufficiently dilated despite an apparently angiographically successful deployment. Methods proposed to overcome these drawbacks haven’t been satisfactory so far. The adequacy of angiographic guidance and evaluation of stent deployment needs to be improved.


Technology Description

Dr. Close from Cedars-Sinai Medical Center proposes an improved image guidance in coronary stent deployment. This new method is based on two techniques:

•       an image processing method known as “moving layer decomposition”; and

•       coronary stent deployment methods using marked delivery guidewires or balloons.

Moving layer decomposition is an image processing method for analyzing a time-series of images, such as coronary angiograms, to obtain an image of the object of interest with clearer signals and lower noises. The method focuses on an identifiable feature in the angiograms (a “layer”), such as a coronary vessel, that moves or rotates with respect to a background across a series of images. It tracks the motion of the feature, and averages the image intensity of the feature using several images of the time-series taking into account the movement of the feature. In the resulting enhanced image, the feature is more clearly visible.

The present invention provides a method for precisely evaluating coronary stent deployment by marking the stent guidewire or delivery balloons using radiopaque marker, and tracking the image of the stent using the moving layer decomposition technique. Although the stent itself is typically not clearly visible, it co-moves with the markers. Thus, by tracking the movements of the markers and performing time averaging based on the tracking, the visibility of the stent or stented lumen can be enhanced.


Stage of Development

Concept only



Although artificial radiopaque markers have been used in other image processing methods to enhance an image feature of interest other than the marker, the method has never been used in combination with moving layer decomposition. In addition, the technique of moving layer decomposition can be applied to images of the opacified lumen following stent deployment in order to improve the assessment of stent dilation.



Coronary stent deployment


Intellectual Property

•       US patent 6532380 granted.

Patent Information:
For Information, Contact:
Julien Brohan
Robert Close
James Whiting
Craig Abbey