Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-02-22
2001-01-09
Kamm, William E. (Department: 3762)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C606S130000
Reexamination Certificate
active
06173201
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to the diagnosis and treatment of ailments such as cancer and, more particularly, to a method of stereotactic diagnosis and treatment with reference to an image of the target region of the patient that combines a high-resolution structural image such as a CT or MRI image with a lower resolution functional image such as a nuclear image.
Several diagnostic and therapeutic techniques that are used to diagnose or treat cancer involve the insertion of an instrument such as a needle, from outside the patient, into a tumor that is suspected of being cancerous. For example, a biopsy needle commonly is inserted into the tumor to withdraw a tissue sample for biopsy. In brachytherapy, a radioisotope is placed at the tip of a needle, and the tip of the needle is inserted into the tumor to deliver radiation to the tumor with minimal irradiation of the surrounding healthy tissue. Chemotherapeutic agents also may be injected into the tumor using a needle. The needles often are inserted into the patient with reference to a series of structural images of the patient, such as ultrasound images or CT images. These images are acquired before and during the insertion of the instrument, to verify that the instrument is being directed towards the correct target and is bypassing organs such as blood vessels which should not be penetrated by the instrument.
A tumor may include both cancerous tissue and non-cancerous tissue. It would be useful to be able to direct an instrument specifically to a cancerous portion of a tumor, and to avoid an obviously non-cancerous portion of a tumor. In the case of a biopsy, the needle should be directed towards the portion of the tumor that is most likely to be cancerous. In the case of brachytherapy, the needle should be directed towards the portion of the tumor that is known to be cancerous. Structural imaging modalities, such as CT and MRI, that have enough spatial accuracy and resolution to distinguish resolve tumors, are nevertheless unable to differentiate cancerous tissue from noncancerous tissue because they resolve only structure. Functional imaging modalities, including tomographic nuclear imaging modalities such as SPECT and PET, can distinguish cancerous tissue from noncancerous tissue but lack the spatial accuracy and resolution that is needed for the accurate positioning of instruments such as biopsy needles and brachytherapy needles.
It is known to register a functional image with a structural image to produce a combined image. See, for example, M. W. Vannier and D. E. Gayou, “Automated registration of multimodality images”,
Radiology
, vol. 169 pp. 860-861 (1988); J. A. Correia, “Registration of nuclear medicine images,
J. Nucl. Med
., vol. 31 pp. 1227-1229 (1990); J-C Liehn, A. Loboguerrero, C. Perault and L. Demange, “superposition of computed tomography and single photon emission tomography immunoscinigraphic images in the pelvis: validation in patients with colorectal or ovarian carcinoma recurrence”,
Eur. J. Nucl. Med
., vol. 19 pp. 186-194 (1992); F. Thomas et al., “Description of a prototype emission transmission computed tomography imaging system”,
J. Nucl. Med
., vol. 33 pp. 1881-1887 (1992); D. A. Weber and M. Ivanovic, “Correlative image registration”,
Sem. Nucl. Med
., vol. 24 pp. 311-323 (1994); and Hasegawa et al., U.S. Pat. No. 5,376,795. All six of these prior art documents are incorporated herein by reference for all purposes as if fully set forth herein. In principle, a sequence of such combined images could be used to direct an instrument to the cancerous portion of a tumor. In practice, the multiple imaging sessions and registrations that this would require make this solution impractical and possibly dangerous.
Stereotaxis is a known technique for localizing a region inside the body of a patient from outside the body of the patient, and for directing an instrument such as a needle, or a narrow beam of therapeutic radiation, to the target region. The degree of accuracy needed for stereotaxis is relatively high, so that the technique has been considered useful mainly on the brain and the breast. For example, in stereotactic radiosurgery of the brain, a CT localization frame is attached rigidly to the head of a patient and a CT image of the patient's brain is acquired with the CT localization frame in place. The position of the CT localization frame in the CT image is used to position the patient with respect to the source of the beam of radiation so that the beam intersects the desired target. Note that the CT localization frame is removed from the patient's head before the therapeutic irradiation commences.
There is thus a widely recognized need for, and it would be highly advantageous to have, a method of stereotactic diagnosis and therapy that could be used to direct a diagnostic or therapeutic instrument to a cancerous portion of a tumor located in a portion of a patient other than the patient's head or breast.
DEFINITIONS
As used herein, the term “target” refers to a structurally discrete portion of the patient, such as an organ or a tumor, that is suspected of including diseased tissue but that also may include healthy or noncancerous tissue.
As used herein, the term “therapeutic instrument” refers to an instrument that is inserted in the target from outside the patient for the purpose of either diagnosis of disease or treatment of disease. Typical examples of therapeutic instruments include biopsy needles and needles for brachytherapy and chemotherapy.
SUMMARY OF THE INVENTION
According to the present invention there is provided a method for diagnosing and accessing a target in a patient, including the steps of: (a) rigidly securing a frame to the patient, the frame including at least three markers; (b) imaging at least a portion of the patient including the target, using a structural imaging modality, to produce a structural image of the at least portion of the patient and of the markers; (c) imaging the at least portion of the patient using a functional imaging modality to produce a functional image of the at least portion of the patient; and (d) if a presence of a diseased portion of the target is indicated in the functional image: (i) registering the functional image with the structural image to produce a first combined image, (ii) rigidly attaching a stereotactic guide to the frame, and (iii) directing a therapeutic instrument to the diseased portion of the target, using the stereotactic guide, with reference to the diseased portion and to the markers as imaged on the first combined image.
Although the scope of the present invention includes the diagnosis and treatment of any diseased tissue, the present invention is described below in terms of the primary application thereof, the diagnosis and treatment of cancer.
In the first phase of the present invention, a frame is rigidly attached to the patient and a portion of the patient including the target is imaged using a high-resolution structural imaging modality such as CT or MRI. The frame includes markers that are recorded in the structural image so that the position of any other point in the image relative to the frame can be determined.
In the second phase of the present invention, a suitable radiopharmaceutical, that is taken up preferentially by cancerous tissue, is injected into the patient, and the portion of the patient that was imaged in the first phase is again imaged using a lower-resolution, functional imaging modality that records the radiation emitted by the radiopharmaceutical to give an image of the cancerous part of the target. The structural image and the functional image are registered to provide a combined image that shows which part of the tumor mass contains cancer and where the cancerous areas are on the high-resolution image.
In the third phase of the present invention, a stereotactic guide is rigidly attached to the frame. Because the position of the cancerous tissue relative to the frame is known, the position of the cancerous tissue relative to the stereotact
Kamm William E.
V-Target Ltd.
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