Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-06-04
2002-04-23
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S431000, C378S037000, C250S363020
Reexamination Certificate
active
06377838
ABSTRACT:
BACKGROUND OF THE INVENTION
Radiation imaging systems typically are used to generate images of the distribution of radiation either transmitted through an object or emitted from an object. Such radiation is not visible to the naked eye. The various modalities of imaging distributions of radiation include Transmission Imaging and Emission Imaging. Both of these modalities are applied in medicine.
Classical transmission imaging or x-ray radiography is a technique wherein the radiation is generated externally and caused to propagate through an organ or body to the detector. In this way an image of the distribution of radiation absorption, or transmission, in the organ or body is obtained. One of the examples of the transmission imaging is mammography used for providing images of the breast in sufficient detail to assure high sensitivity screening for abnormal tissue.
Mammography is accepted as the best means of screening for non-palpable breast cancer. However, signatures of breast cancer, such as micro-calcifications or masses, seen for most malignant lesions, are also associated with benign processes. Thus, while the sensitivity of mammography is reported to be about 85%, its specificity is only 20-30%, and only about 30% of biopsies based on mammography are positive according to the following papers: “Tc-99m-Sesta MIBI Prone Imaging in Patients (PTS) with Suspicion of Breast Cancer (Ca)” by Khalkhali, I., I. Mena, E. Jouanne, L. Diggles, K. Alle, S. Klein in J. Nucl. Med., 24:140P, May 1993, “Sensitivity and specificity of first screen mammography in the Canadian National Breast Screening Study: a preliminary report from five centres” by Baines C J; Miller A B; Wall C; McFarlane D V; Simor I S; Jong R; Shapiro B J; Audet L; Petitclerc M; Ouimet-Oliva D; et al; in Radiology, 160:295-298, (1986), and “Mammographic parenchymal patterns: risk indicator for breast cancer?” by Tabar, L. and Dean P B, in JAMA 247:185-189, (1982).
Excisional biopsies on a false positive patient result in large unnecessary costs and the scarring that can cause difficulties in interpretation of future mammograms according to a paper titled “Radiographic Breast Anatomy: Radiological Signs of Breast Cancer” by Shaw de Paredes E. in Syllabus: A Categorical Course in Physics & Technical Aspects of Breast Imaging, eds. A. G. Haus & M. J. Yaffe, RSNA Publications, Oak Brook Ill., 1992. Many centers now use stereotactic systems for core biopsies immediately after mammography, while the breast is compressed in the same position as in the mammogram. While the stereotactic procedure is somewhat less traumatic, the cost is still significant, especially for the 70% of patients who had false positives.
In emission imaging (“Nuclear Medicine”) radiation is generated within the organ by radiopharmaceutical or other radiation bearing substance which passes through or in some cases is designed to accumulate in the organ. Many emission imaging applications exist including single photon planar imaging and Single Photon Emission Computed Tomography (SPECT) for imaging the structure or function of internal organs.
Gamma-ray cameras employed in single photon emission imaging applications typically consist of a collimator for “focusing” the gamma-rays, a detector for determining the position of each incident gamma-ray and a device for displaying the acquired images. Traditional gamma-ray cameras utilize scintillation detectors coupled to photomultiplier tubes (PMT's) for detecting the light emitted from the scintillator. This development is described in a paper titled “Scintillation Camera”, by Hal O. Anger, published 1958, The Review of Scientific Instruments, Vol. 29 No. 1 and in a paper titled “Gamma-Camera Systems,” by M. D. Short, in 1984, Nuclear Instruments and Methods, Vol. 221. In these cameras, the scintillator is generally a single crystal (70 cm diameter) which is coupled to multiple PMT's. Each PMT covers several square centimeters of area of the scintillation crystal. Recently, smaller, higher spatial and energy resolution gamma-ray cameras dedicated to particular applications have been developed or are under development. These new cameras are based on PMT's, position sensitive PMT's (PSPMT) or solid state detectors. The solid state detector based camera can be one which has a scintillator coupled to a solid state detector. In this case the solid state detector has replaced the PMT or PSPMT as the device which converts the light emanating from the scintillator into electrical signals. A typical example of such an implementation is a gamma-ray camera based on a silicon pin photodetector array coupled to CsI(Tl) scintillator described in U.S. Pat. No. 5,773,829, which is incorporated by reference in its entirety into the present disclosure. Another approach utilizes a solid state detector, which directly converts the radiation to electrical signals.
An example of emission imaging is breast imaging using the radiopharmaceutical MiraLuma™ (Tc-99m-Sestamibi). Recent developments in testing of this radiopharmaceutical, which was initially developed for measuring blood flow in the myocardium, show that the compound is also selectively taken up in tumors, apparently in proportion to the malignancy of the tumor. The compound compares favorably with Tl-201 in tumor uptake as described in the papers titled “In vitro uptake of technetium-99m-teboroxime in carcinoma cell lines and normal cells: comparison with technetium-99m-Sestamibi and thallium-201 ” by Maublant J C; Zhang Z; Rapp M; Ollier M; Michelot J; Veyre in A. J. Nuc. Med., 1993 November, 34 (11):1949‥52, “Thallium-201 versus technetium-99m-MIBI SPECT in evaluation of childhood brain tumors: a within-subject comparison” by O'Tuama L A; Treves S T; Larar J N; Packard A B; Kwan A J; Barnes P D; Scott R M; Black P M; Madsen J R; Goumnerova L C et al. in J. Nuc. Med., 1993 July, 34(7):1045-51., and “Concordant uptake of Tc-99m Sestamibi and Tl-201 in unsuspected breast tumor” by Campeau R J; Kronemer K A; Sutherland C M, in Clin. Nucl. Med., 1992 December, 17 (12):936-7. It is believed that the Tl-201 uptake is a measure of blood flow, while the Sestamibi is sensitive to tumor metabolic rate or malignancy. In addition, Sestamibi's mechanism of uptake fixes the compound and minimizes redistribution. Uptake of Sestamibi is also very rapid. It is fixed in the heart, liver and tumor in about 10 minutes, and has a maximum uptake in the tumor at about 5 minutes. Recent reports such as the one reported in papers on detection of breast tumors using Sestamibi titled “Scintimammography: the complementary role of Tc-99 m Sestamibi prone breast imaging for the diagnosis of breast carcinoma” by I. Khalkhali, J. A. Cutrone, I. G. Mena, L. E. Dingles, et al., in Radiology 196 (1995):421-426, and “Technetium-99m-Sestamibi Prone Scinti-mammography to Detect Primary Breast Cancer and Axillary Lymph Node Involvement” by Taillefer, R., Robidoux, A., Lambert, R., Turpin, S., and Laperriere, J. in J. Nuc. Med. 36:1758, October 1995, all give sensitivities and specificities in the neighborhood of 90%. Recently, equally encouraging results were also reported for Tc-99m-Methylene Diphosphonate (MDP) with a sensitivity of 92% and a specificity of 95% in a paper titled “Technetium-99m-Methylene Diphosphonate Scintimammography to Image Primary Breast Cancer” by Piccolo, S., Lastoria, S., Mainolfi, C., Muto, P., Bazzicalupo, L., Salvatore, M. in J. Nuc. Med. 1995. 36:718-724.
Part of the 10% or so of the lesions missed in the studies such as the ones reported by Kalkhali and Taillefer cited above were due to the small size and/or lower uptake of the particular lesions. In one study reported in a paper titled “Technetium-99m-sestamibi uptake in breast tumor and associated lymph nodes” by J. Maublant, M. de Latour, D. Mestas, et al. in J. Nucl. Med. 37 (1996):922-925, patients were injected with Tc-99 m Sestamibi and imaged with a scintillation camera one day prior to a second injection of Sestamibi prior to excisional breast and/or axillary biopsy. All pati
Iwanczyk Jan S.
Patt Bradley E.
Christie Parker & Hale LLP
Lateef Marvin M.
Mantis Mercader Eleni
Photon Imaging, Inc.
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