Measuring Catheter Orientation in MRI
Lipid-rich coronary lesions have a high risk of rupture. Early detection and quantification of these using interventional coronary catheterization for high-risk patients is necessary to increase the chances of successful treatment and prevention.
During the catheterization process, catheters are inserted with measurement equipment at their tips. These scan their immediate surroundings and indicate levels of limpidity and calcium enrichment.
Top Spin Medical developed a unique catheter with MRI-like capabilities, which has undergone installation and clinical testing at hospitals. With insertion of this catheter, pulses returning from surrounding tissues to the tip of the catheter allow measurements of tissue parameters such as its lipid layer or calcium composition and alert the physician to the placement of lesions. The exact position of the lesion has to be pinpointed for the accuracy of the interventional procedure and to decrease the risk upon operating. Hence the need for measurement of catheter orientation.
The problem is that the orientation of the catheter’s tip is unknown throughout insertion. Thus the exact location cannot be accurately given. To view the catheter along its insertion and positioning, physicians use local x-ray imaging. In these images the outer envelope of the tip is clearly visible. However, x-ray images are two-dimensional, and so when the catheter tip is oriented perpendicular to the plane of the image, physicians cannot tell whether it points inward or outwards.
By employing advanced algorithmic methods, RSIP Vision has constructed a method to ascertain the catheter’s tip orientation from x-ray images – catheter orientation measurement. Single x-ray images obtained during catheter insertion provide the input to our algorithms. During the first stage, the catheter tip is segmented in the images. The tip’s opacity in the image is then used to tell its orientation. Using our algorithms, both orientation information can be used by the physician during catheterization, and more accurate positions of lipid lesions can be given at the examination site of the catheter.