Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-12-20
2001-09-18
Jaworski, Francis J. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S445000, C600S463000, C600S437000
Reexamination Certificate
active
06292681
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains generally to diagnostic and therapeutic ultrasonic imaging systems and, more particularly, to apparatus for providing automated longitudinal position translation in ultrasonic imaging systems.
BACKGROUND OF THE INVENTION
Probe assemblies having therapeutic and/or diagnostic capabilities are being increasingly utilized by the medical community as an aid to treatment and/or diagnosis of intravascular and other organ ailments. In this regard, U.S. Pat. No. 5,115,814 discloses an intravascular ultrasonic imaging assembly with a distally located imaging element that is positionable relative to intravascular sites. Operation of the imaging element in conjunction with associated electronic image recovery components generates visible images that aid an attending physician in his or her treatment of a patient's vascular ailments. In particular, a physician may view in real (or essentially near real) time intravascular images generated by the ultrasonic imaging probe element to locate and identify intravascular abnormalities that may be present and thereby prescribe the appropriate treatment and/or therapy.
The need to accurately position a distally located operative imaging element relative to an intravascular site using any therapeutic and/or diagnostic probe assembly is important so that the attending physician can confidently determine the location of any abnormalities within the patient's intravascular system. Accurate intravascular position information for the imaging assembly will also enable the physician to later replicate the same positions for subsequent therapeutic and/or diagnostic procedures, e.g., to enable the physician to administer a prescribed treatment regimen over time and/or to later monitor the effects of earlier therapeutic procedures.
By using computer-assisted reconstruction algorithms, current ultrasonic imaging systems enable physicians to view a representation of the patient's interior intravascular structures in both two and three dimensions (i.e., so-called three dimensional or longitudinal view reconstruction). To this end, image reconstruction algorithms employ data-averaging techniques which assume the intravascular structure between an adjacent pair of data samples is an average of each such data sample, i.e., the algorithms use graphical “fill in” techniques to depict a selected section of a patient's vascular system under investigation. Of course, if data samples are not sufficiently closely spaced, lesions and/or other vessel abnormalities may go undetected, since they might lie between a pair of data samples and thereby be “masked” by the image reconstruction algorithms.
As such, current reconstruction algorithms depend upon the ability to obtain and process very precisely longitudinally separated data samples of a section of a patient's vascular system under investigation. To this end, automated longitudinal translation of a distally located ultrasound imaging element is often employed to ensure the data samples are precisely spaced. For example, U.S. Pat. No. 5,485,486 discloses an imaging system in which an ultrasound imaging transducer is mounted on a distal tip of a rotating cable extending through a lumen of a catheter placed in a patient's vascular system, wherein the distal tip of the rotating cable is translated longitudinally at a precise constant rate through the use of a longitudinal translation assembly. In particular, the longitudinal translation assembly enables a series of precisely separated data samples to be obtained thereby minimizing (if not eliminating) distorted and/or inaccurate reconstructions of the ultrasonically scanned vessel section, i.e., since a greater number of more closely spaced data samples can reliably be obtained. Further, a precisely controlled pullback speed makes it possible to take measurements in a longitudinal direction, e.g., a lesion length.
Notably, a main advantage of this automated pullback assembly is that it can be operated in a “hands-off” manner which allows the physician to devote his or her attention entirely to the real-time images with the assurance that all sections of the vessel are displayed. On the other hand, the disclosed system is relatively large and can be cumbersome for a physician to set up, in part because the longitudinal translation assembly and a rotary drive motor used to rotate the imaging cable must each be wrapped in separate sterile drapes (i.e., plastic bags) in order to perform the imaging procedure.
U.S. Pat. No. 5,361,768 discloses an improved system over that disclosed in U.S. Pat. No. 5,485,486, in that a single drive unit provides the requisite longitudinal and rotational translation of the imaging cable. However, the respective rotational and longitudinal movement of the cable is still provided by separate motors, thereby making the “combined” drive unit larger and heavier than either of the previous separate units.
Thus, it remains desirable to provide a still further improved drive unit for both rotational and precisely controlled translational movement of an imaging cable in an ultrasonic catheter imaging system.
SUMMARY OF THE INVENTION
The present invention is directed to an ultrasonic imaging system employing a single motor drive unit for providing both rotational and controlled longitudinal translation of an operative imaging cable disposed in a catheter assembly, thereby reducing the size, weight and cost of the system drive unit(s), while at the same time making the imaging system easier to set up and operate.
In a preferred embodiment, the imaging system includes an imaging catheter assembly secured to a single motor drive unit, wherein the imaging catheter assembly generally comprises an outer guide sheath having an operative drive-cable and mounted transducer disposed therein. The motor drive unit includes a main body casing that houses a motor that rotates a drive-shaft at a specific and predetermined rotational drive-shaft speed.
The main body casing includes one or more guide rails that are slidingly mounted on a pullback carriage, such that the main body casing may move longitudinally relative to the pullback carriage. A rigid “pullback arm” is connected at one end to the pullback carriage and at the other end to the proximal opening of the outer guide sheath of the catheter assembly, i.e., such that the main body casing is also movable relative to the outer guide sheath of the catheter assembly as the pullback carriage slides along the guide rail(s). A telescoping inner catheter sheath extends through the fixed proximal opening of the outer guide sheath and is attached to the main body casing of the motor drive unit, with the drive-cable extending through the inner sheath and attached to the motor drive-shaft within the hub, i.e., such that rotation of the motor drive-shaft correspondingly rotates the drive-cable.
In accordance with a first aspect of the invention, the imaging system can be made to operate in an automated longitudinal translation mode, wherein the main body casing of the drive unit is made to uniformly and longitudinally move relative to the pullback carriage by the drive unit motor, thus causing coincident longitudinal movement of the drive-cable (and distally located transducer) relative to the outer guide sheath of the catheter assembly.
In particular, a reduction gear mechanism is mounted circumferentially around the drive-shaft within the main body casing of the drive unit, with the reduction gear mechanism producing an output circumferential speed that is significantly less than the circumferential speed of the drive-shaft. A longitudinal drive train, such as, e.g., a drive screw and threaded collar, is rotatably mounted to the main body casing of the drive unit, engaging the reduction gear mechanism. In order to provide longitudinal movement of the main body casing relative to the pullback carriage, (i.e., while the later is in a fixed, or mounted position), an engagement mechanism associated with the pullback carriage and urged by an expan
Boston Scientific Corporation
Jaworski Francis J.
Lyon & Lyon LLP
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