Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2002-03-18
2004-02-24
Ruhl, Dennis (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S437000, C600S464000, C600S417000
Reexamination Certificate
active
06695786
ABSTRACT:
FIELD
This patent specification relates to medical procedures such as ultrasound-assisted biopsies in which an invasive medical instrument such as a biopsy needle is guided by a medical imaging system such as an ultrasound system. More particularly, it relates to a low-cost apparatus for mounting the instrument to an imaging probe, controlling its position, monitoring its position, and/or predictively displaying its position on a user display of the medical imaging system.
BACKGROUND
Ultrasound imaging systems have become increasingly popular for use in medical applications because they are non-invasive, easy to use, capable of real-time operation, and do not subject patients to the dangers of electromagnetic radiation. Instead of electromagnetic radiation, an ultrasound imaging system transmits sound waves of very high frequency (e.g., 1 MHz to 15 MHz) into the patient and processes echoes from structures in the patient's body to derive and display information relating to these structures. Although the preferred embodiments are described infra with respect to an ultrasound imaging environment, it is to be appreciated that they are also applicable in the context of other medical imaging environments including computerized tomography (CT), magnetic resonance imaging (MRI), and other environments.
Among other useful applications, ultrasound imaging systems are used in invasive surgical procedures such as biopsies. In such a use, the ultrasound imaging system is used to locate a region of interest in the patient, such as a tumor, and to assist the doctor or other medical professional (hereinafter “user”) in guiding a biopsy needle to the tumor. As known in the art, ultrasound imaging systems generally only provide an image of a single plane within the patient as determined by the position and orientation of the ultrasound probe head. In particular, the imaged plane is usually a plane defined by the intersection of two lines, the first line being along a transducer array surface of the probe head, the second line being perpendicular to the first line along a center axis of the probe head. It is necessary to keep the biopsy needle positioned within the imaged plane in order for it to remain visible on the ultrasound monitor during the procedure.
Biopsy needle guides have been proposed for attaching biopsy needles to ultrasound probes and restricting movement of biopsy needles to the imaged plane.
FIG. 1
illustrates a needle guide
100
proposed in U.S. Pat. No. 5,623,931, which is incorporated by reference herein, in which a probe clip
110
attaches to an ultrasound probe, and in which the biopsy needle is slidably guided by one of three grooves
111
, thereby constraining its movement to within the imaged plane.
FIG. 2
illustrates a needle guide
19
proposed in U.S. Pat. No. 4,899,756, which is incorporated by reference herein, in which the needle is rotatably affixed to a two-link structure that is, in turn, rotatably affixed to the ultrasound probe. The two-link structure comprises an “ascending link”
22
affixed to the ultrasound probe that is rotatable only in the imaged plane, and a “descending link”
23
that is slidably affixed to the ascending link and rotatable only in the imaged plane. The biopsy needle is thereby constrained to the imaged plane.
The medical realities of many biopsy procedures, including breast tumor biopsy procedures, render the needle guides of FIG.
1
and
FIG. 2
insufficient for many practical situations. Many breast tumor biopsy procedures require a substantial number of different samples or insertions into the tumor, often at incrementally different positions and/or angles. It is often desirable to allow the user to maintain the probe head in a fixed position, thereby keeping the tumor position constant on the ultrasound output screen, while gently and incrementally adjusting the positioning and angle of the needle. As another example, because it is crucial not to puncture the chest wall and lung during the procedure, it is often desirable to insert the needle into the patient at an angle that is approximately parallel to the transducer surface, i.e. at an angle that is approximately 90 degrees from the probe axis. In this way, the ultrasound probe may be placed at a stable position perpendicular to the chest wall on top of the breast, while the needle is inserted at an angle parallel to the chest wall, thereby reducing the possibility of chest wall and lung puncture. Even further, it is desirable to have the ability to place the transducer surface on one side of the breast, while allowing the biopsy needle to be inserted on the other side of the breast, whereby the biopsy needle may enter the breast at an angle up to 180 degrees with respect to the probe axis. Still further, it is often desirable to insert the needle at a direct zero-degree angle with respect to the probe axis at a point directly adjacent to the transducer array.
While the needle guide of
FIG. 2
allows more freedom of needle movement than the device of
FIG. 1
, it nevertheless presents substantial restrictions on needle movement and position within the imaged plane. For example, the two-link device is not readily amenable to allowing the zero-degree insertion (i.e., parallel to probe axis) of a biopsy needle at a point adjacent to the probe head, or of allowing a 180-degree insertion at a breast point opposite the probe head. It would be desirable to provide a biopsy needle guide that allows for substantially unfettered freedom of movement of a biopsy needle within the imaged plane of an ultrasound system, both in terms of needle angle and needle entry point.
Moreover, because a biopsy needle represents a thin, and often specular, target for the ultrasound system, it is often difficult for the ultrasound system to maintain a clear output image of the biopsy needle that is easily viewable. A clear image of the biopsy needle can be difficult to obtain even if its movement is restricted to the imaged plane. One method for dealing with this problem involves the performance of image recognition algorithms on the ultrasound image to identify and segment the biopsy needle, with the needle position and orientation then being highlighted on the display screen. The needle highlight usually comprises a bright-colored or otherwise noticeable line positioned at the computed needle position. Unfortunately, the image recognition algorithms often require extensive processing power, and output frame rates can suffer accordingly. Also, these image processing algorithms can at least partially fail if the needle wanders from the imaged plane. Finally, because of the appreciable amount of computation required, quick movements of the biopsy needle can cause jittery and/or delayed needle highlights.
Another method for dealing with needle visualization problems during ultrasound-assisted biopsy procedures is to mount three-dimensional position and orientation sensors, such as magnetic sensors, on the ultrasound transducer and the biopsy needle handle. The position and orientation sensors provide the position (x,y,z) and orientation (&rgr;,&thgr;,&phgr;) of both the transducer and the needle handle to the ultrasound system. This allows for prompt computation of the position and orientation of the biopsy needle relative to the ultrasound image slice being displayed. The biopsy needle is manipulated “free-hand” and can depart from the imaged plane, with special designations on the highlighted display to indicate departure from the imaged plane. An example of one such system is the UltraGuide® 1000 available from UltraGuide, Inc. of Lakewood, Colo.; see also U.S. Pat. No. 6,216,029, which is incorporated by reference herein.
One or more practical disadvantages, however, are associated with systems based on three-dimensional position and orientation sensing. First, although they allow for “free-hand” operation of the biopsy needle, the three-dimensional sensing hardware is quite expensive, whether it be based on magnetic sensing systems, accelerometers, or gyro-based systems. Second, in seve
Chin Donald
Lin Shengtz
Maroc Karen D.
Wang Shih-Ping
Zhang Siqing
Cooper & Dunham LLP
Jung William C.
Ruhl Dennis
U-Systems Inc.
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