Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2001-05-15
2003-02-25
Jaworski, Francis J. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S443000, C600S461000
Reexamination Certificate
active
06524247
ABSTRACT:
FIELD
This patent specification relates to medical ultrasound imaging systems. In particular, it relates to a method and system for enhanced ultrasonic viewing of a specular instrument such as a biopsy needle inserted into the body during a medical procedure.
BACKGROUND
Ultrasound imaging systems are being increasingly used in medical diagnosis, surgery, and treatment 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 scattered from structures in the patient's body to derive and display information relating to these structures.
Among the many practical applications of ultrasound imaging systems is their use during invasive or partially invasive medical procedures for allowing the medical professional to better visualize and control the procedure. For example, a breast biopsy is a medical procedure in which a specialized biopsy needle is inserted into the breast to extract tissue samples of a suspicious lesion or tumor. The biopsy needle must be accurately guided so that its tip enters the lesion. Using an ultrasound imaging system, the physician or other medical professional (hereinafter “user”) can guide the biopsy needle by viewing real-time ultrasound images of the biopsy needle with respect to the target lesion.
A problem, however, arises in practical clinical applications as a result of the thin, specular nature of most biopsy needles. Because they are elongated and narrow, biopsy needles often elude the plane of the ultrasound slice being imaged. When they do intersect this plane, it is often for only brief intervals of time or space.
Another problem arises from the smooth, metallic nature of most biopsy needles. These needles are specular reflectors that, unlike the tissues in the patient's body, do not reflect incident ultrasound pulses in a diffuse manner. This makes the biopsy needle difficult to perceive in the ultrasound output image unless the incident ultrasound pulses approach the biopsy needle at angles close to ninety degrees. Only for those angles close to ninety degrees will the incident pulses be reflected back to the probe transducer array and properly detected. This problem is alleviated somewhat for abdominal procedures (e.g. for heart, liver, and prenatal procedures) that predominantly use curvilinear imaging formats. For curvilinear imaging formats, the scan lines spread out over a substantial ranges of angles, some of which are perpendicular, or close to perpendicular, to the biopsy needle. In contrast, the predominant imaging format for breast biopsy procedures is the linear format, in which the scan lines are generally parallel to each other, thereby making biopsy needle visualization more difficult for many angles. Nevertheless, it is to be appreciated that the preferred embodiments described infra may be used to enhance needle visualization for any type of imaging format, including linear formats, steered linear formats, curvilinear formats, sector formats, vector formats, and other formats.
U.S. Pat. No. 6,048,312 (hereinafter “the '312 patent”), which is incorporated by reference herein, discusses a method for three-dimensional ultrasound imaging of a needle-like instrument, such as a biopsy needle, in which the transmitted ultrasound beams are steered to increase the angle at which they impinge upon the biopsy needle. This increases the system's sensitivity to the needle because the reflections from the needle are directed closer to the transducer array. The steered image frames, i.e., the image frames formed from the steered ultrasound beams, may be superimposed with non-steered image frames to form a composite image, and the needle may be highlighted using an intensity-mapping procedure. When the position of the biopsy needle is undetermined, a non-steered first image frame may be combined with a second image frame acquired by steering the beam at a constant first steering angle and with a third image frame acquired by steering the beam at a constant second steering angle, to increase visibility of the biopsy needle.
However, the '312 patent leaves several problems associated with biopsy needle imaging unresolved. For example, while the beams are steered by a transmitter and receiver that “are operated under control of a host computer or master controller [ ] responsive to commands by a human operator,” (col. 5, lines
63
-
65
), the nature of the system's determination of the biopsy needle position is not clear. As another example, the acquired 2-D ultrasound slices have reduced visibility of the biopsy needle when it is positioned out-of-plane with respect to the ultrasound slice. As described supra, this problem is caused by the elongated, narrow shape of the biopsy needed. This problem can be at least partially remedied by a method disclosed in the '312 patent, a “cut plane rotate” method, in which the user graphically manipulates a slice within a 3-D volume construction of the target region until the biopsy needle is coplanar with the slice, wherein data from the 3D volume corresponding to the slice is then displayed (col. 11, lines
18
-
44
). However, this process is highly computationally intensive, and may therefore be difficult to achieve in a real-time system in a cost-effective manner. Moreover, this procedure demands a substantial amount of user attention and manipulation of the ultrasound user interface. Often, the user is already highly occupied with the biopsy procedure being performed, and does not want to devote an undue amount of time and attention to a system that is supposed to be making things easier.
Accordingly, it would be desirable to provide an ultrasound system with real-time biopsy needle visualization enhancement for a wide range of needle positions with respect to the probe.
It would be further desirable to provide such an ultrasound system in which biopsy needle visualization may be enhanced when the needle position is not predetermined or provided to the system by the user.
It would be further desirable to provide such an ultrasound system having an optional mode in which estimates of the position of the biopsy needle may be easily provided by the user, the ultrasound system having an intuitive, easy-to-use user interface that does not require excessive user manipulation.
It would be even further desirable to provide such an ultrasound system in which biopsy needle visualization may be enhanced even when the biopsy needle may wander or deviate from the plane of the ultrasound slice being imaged.
It would be still further desirable to provide such an ultrasound system that provides such biopsy needle visualization enhancement without requiring the computational intensity associated with 3-D volume construction.
SUMMARY
A method and system for real-time visualization enhancement of a biopsy needle are provided, wherein a wide range of needle positions with respect to the probe axis and with respect to the imaged plane are accommodated. Ordinary ultrasound frames are compounded with special purpose ultrasound frames and then output to a real-time display, the special purpose ultrasound frames having transmit and receive parameters adapted to highlight reception of ultrasound echoes from the biopsy needle. In one preferred embodiment, an elevation beam width associated with the special purpose ultrasound frames is wider than an elevation beam width associated with the ordinary ultrasound frames. This reduces sensitivity to the position of the biopsy needle with respect to the imaged plane, and increases reception of biopsy needle echoes in cases where the biopsy needle deviates from the imaged plane. Methods for increasing the elevation beam width of the special purpose frames include lowering the operating frequency and managing the elevation aperture.
Preferably, the beams of the special purpose ultr
Cupples Tommy Earl
Yu Zengpin
Zhao Danhua
Jaworski Francis J.
U-Systems Inc.
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