Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-04-13
2002-12-24
Smith, Ruth S. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S424000, C600S427000
Reexamination Certificate
active
06498944
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of intrabody position determination, and specifically to intrabody measurements using position determination.
BACKGROUND OF THE INVENTION
There are many cases in which it is desired to measure organs or spaces within a patient's body. One such case is in preparation for organ transplantation. In transplantation procedures, in order to speed up the transplantation procedure and minimize the period in which the patient is without the transplanted organ, the new organ is preferably prepared before the transplantation procedure. In order to ensure proper reception of the new organ, it must be as similar as possible to the organ that is removed. In some organs the similarity in size may be approximate, since the surroundings of the organ are elastic. However, in other cases, the new organ must fit precisely in place of the old one.
In other cases, an empty space within a body is to be filled. For example, a patient may be missing a piece of a bone which is to be replaced by an artificial implant. Precise measurement of the space allows preparation of the artificial piece before its implantation, and may enable automatic fabrication of the artificial piece.
Measurements within a patient's body may be used also for other reasons, such as inspection and diagnosis. For example, in some cases, a tumor may be analyzed according to its size and/or its shape to track the progress of therapy or to plan a surgical operation. In tumor removal surgery, measurement of the tumor before, during, and after the surgery may be performed to verify removal of all or a desired portion of the tumor.
In the art, measuring an organ or a space within a body is usually performed on CT or MRI images, or using ultrasound. U.S. Pat. No.5,370,692 to Fink et al., which is incorporated herein by reference, describes a method of approximately fabricating prosthetic bone implants according to a CT image. However, these measurements are less accurate than direct measurements of the bone dimensions. In addition, some organs have a complicated geometry and therefore are hard to measure even on accurate images. Furthermore, some organs, such as the heart, are in movement and cannot be imaged fast enough to allow production of a clear and still image which can be measured.
There has been a system proposed for producing a prosthetic device, based on an arm which is connected through motion detectors to a model carver. A tip of the arm is moved on an outer surface of an organ, so as to produce a model of the organ. The use of such arms is limited to organs which are easily accessible to the arm, and therefore in most cases this system cannot be used in minimally invasive procedures. In addition, using more than one arm simultaneously is very difficult, since multiple arms interfere with each other.
When aligning bones, regions between bone fractures should be of minimal size, to ensure that the bone properly heals. Ordinarily, one or more X-ray images are taken of the broken bone, and the pieces are aligned accordingly. However, when the fracture is complicated, many images may be necessary, causing the surgeon and patient to be exposed to large amounts of radiation.
U.S. Pat. No. 5,558,091 describes a method of aligning sections of a broken bone, by observing a continually-updated image. The image is initially acquired using X-rays, but is then updated by computer image processing, based on a position determining system which tracks the movements of sensors attached to the bones. However, this method requires producing a separate sub-image for each bone section, and therefore is not suitable for multiple fracture pieces. Also, it would be useful to have a method of accurately realizing the proper alignment of the bones independent of the images.
SUMMARY OF THE INVENTION
It is an object of some aspects of the present invention to provide a method for accurate measurement of organs and spaces within a human body.
It is another object of some aspects of the present invention to provide a method of three-dimensional mapping of an organ situated within a human body.
It is a further object of some aspects of the present invention to provide a method for producing a three dimensional model of an organ which is situated within a human body.
Another object of some aspects of the present invention is to provide a method of aligning bone fractures without unduly exposing the patient and staff to large amounts of radiation.
Another object of some aspects of the present invention is to continuously report volumes or other sizes of regions between intrabody organs, such as bone fractures.
In some preferred embodiments of the present invention, one or more miniature position measuring sensors are placed at selected points within a patient's body. A position determining system, preferably situated outside the patient's body, determines the coordinates of the sensors. Calculating circuitry associated with the position determining system calculates distances between the points, based on the coordinates. Thus, an organ can be measured by placing the sensors at extreme points of the organ and determining the coordinates of the points.
Preferably, the position determining system determines positions based on transmitting and detecting electromagnetic waves, and the sensors comprise miniature coils, in which currents flow responsive to the electromagnetic waves. Alternatively, the position determining system may operate using infrared or ultrasound waves or any other suitable non-ionizing fields, and the sensors accordingly comprise suitable transponders.
In some preferred embodiments of the present invention, position sensors are mounted onto or embedded within an object, for example, a screw, staple, electrode or shunt, which is implanted in the body. The position sensors may be used both for guiding the object into the body, and later on for measurement of intrabody spaces that the object adjoins.
In some preferred embodiments of the present invention, the sensors are placed at a plurality of points on an outer or inner surface of an organ, while the position determining system continuously determines and records the coordinates of these points, preferably at a high sampling rate. The calculating circuitry calculates the size of the organ according to the recorded coordinates. Preferably, the sensors are mounted on the tip of one or more catheters, so as to allow easy movement of the sensors along the surface of the measured organ.
In some preferred embodiments of the present invention, one or more reference sensors are placed within the patient's body for use in making an intrabody measurement. These reference sensors are fixed in place by an operator of the catheter, for example, by a surgeon and are substantially not moved thereafter, during the measurement. The reference sensors are preferably fixed to one of the patient's organs, such as the heart, so that the movements of the reference sensors follow the movements of the patient or of the organ. The coordinates of the reference sensors are determined by the position determining system and are used by the calculating circuitry to transform the (time-varying) coordinates of the recorded points to a stationary coordinate system. Preferably, for each point that is recorded, the position determining system determines simultaneously the coordinates of the measuring position sensor and of at least one of the reference sensors. The calculating circuitry transforms the coordinates of the point to a frame of reference that is fixed to the moving organ.
Preferably, measurement of the organ is performed using a catheter, which may be inserted into the patient for other purposes, as well. In a preferred embodiment of the present invention, a heart valve is examined using a measuring catheter, before and after a valve replacement procedure. Preferably, the valve is replaced in a minimally-invasive procedure, using, for example, the Port-Access(TM) MVR system, supplied by Heartport Inc. The po
Ben-Haim Shlomo
Fenster Maier
Biosense Inc.
Capezzuto Louis J.
Smith Ruth S.
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