X-ray or gamma ray systems or devices – Electronic circuit – With display or signaling
Reexamination Certificate
2000-02-18
2001-09-04
Kim, Robert H. (Department: 2882)
X-ray or gamma ray systems or devices
Electronic circuit
With display or signaling
C378S062000, C378S098000, C378S098200
Reexamination Certificate
active
06285739
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the art of radiography, and more particularly to a new and improved radiographic imaging apparatus and method optimized for vascular interventions for providing region of interest micro-angiography.
After heart disease and cancer the most significant cause of death in the United States is cerebrovascular disease. The three most common cerebrovascular pathologies are stenoses or narrowing due to vessel degeneration, aneurysms or bulges, and arteriovenous malformations (AVM) which act as short circuits. Hemorrhage and other incidents due to these pathologies or acute thrombogenesis leading to vessel constriction or blockage can lead to stroke resulting in death or devastating effects to the individual who survives.
Often in the past the treatment of choice, although not always possible, was invasive surgery that can carry substantial risks of its own. Image-guided minimally invasive endovascular treatments primarily radiographically guided are becoming increasingly preferred. As these new procedures evolve with smaller and finer catheters and devices, they are placing greater requirements on image quality. Thus, there is a growing requirement for high spatial resolution during endovascular interventions. Clinical decisions for balloon expansion of a stent or attempts to mold the stent within the treated vessel depend upon images with adequate detail. Seeing the spatial relationship between overlapping stents where these may be required is now difficult. Detecting the drift of stents during the placement process is difficult. With newer stents having smaller gauge wire and more complex design it is becoming very difficult to see even the gross shape of the stent let alone to determine the status of the individual segments or wires. As the endovascular devices progress toward treatments of smaller vessels within or beyond the circle of Willis, there will be the additional concern about disturbing or blocking the origin of perforators. These perforators that are 50-500 &mgr;m in diameter are often extremely important vessels for specific, key neurological functions, and if blocked can produce devastating deficits in the patient. Perforators seen during invasive micro-surgery typically cannot be visualized by any means during image-guided endovascular procedures. For aneurysm treatment with detachable coils, the thin strands of overlapping coils are typically blurred together into a dense mass with standard DA equipment. Visualization of the detailed shape of the aneurysm and the location and spacing of coil loops could foretell the outcome of the treatment. Finally, for AVM treatment with glue, present images are inadequate in allowing exact evaluation of the filling of small vessels to prevent recurrence.
SUMMARY OF THE INVENTION
Although there is a real need for substantially improved spatial resolution for the images used to guide endovascular procedures, this improvement is not necessarily needed throughout the course of the procedure for the full viewing field. Therefore, in accordance with the present invention it is proposed that improved images are needed only for a region of interest at the site of the intervention, and only during those times during the procedure when crucial decisions must be made either to modify or to end the procedure.
The present invention provides a radiographic imaging apparatus and method for vascular interventions for acquiring very high resolution radiographic images over a small region of interest (ROI). The apparatus and associated method employs digital solid state x-ray image detectors for the medical imaging application of angiography. A mechanical arrangement, for example an arm attached to an existing large area x-ray detector, allows the small area ROI digital detector to be temporarily positioned over a region located by the standard large area imager so that additional very high resolution digital images may be obtained over the ROI. Although large area spot film devices for analog screen/film combination detectors used in the past have better spatial resolution than the standard image intensifier (II) based systems generally used in medical angiographic facilities, the film must be chemically processed preventing an immediate display of the image and making not practicable the subtraction of background structures which is easily achievable with digital imagers. The present invention provides an entirely digital device of very high resolution for use in this small field of view spot imaging application which is capable of immediate image display as well as of mask image subtraction. The high resolution digital ROI imager can comprise an x-ray absorbent phosphor optically coupled to a fiber optic taper which minifies the image and presents it to one large area or an array of smaller charge coupled device (CCD) light sensors. The main application for the apparatus and method of the present invention appears to be during interventional procedures in the region of the intervention, generally near the catheter tip. In cerebro-vascular interventions, smaller and smaller catheters, guide wires, and interventional devices such as stents and coils are being used which are difficult to visualize with conventional II-based imaging systems. The method and apparatus of the present invention thus provides a change in the design paradigm for radiographic detectors to optimize imaging of a region of interest for endovascular interventions.
The foregoing and additional advantages and characterizing features of the present invention will become clearly apparent upon a reading of the ensuing detailed description together with the included drawing wherein:
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Bednarek Daniel R.
Lieber Baruch B.
Rudin Stephen
Wakhloo Ajay Kumar
Ho Allen C
Hodgson & Russ LLP
Kim Robert H.
The Research Foundation of State University of New York
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