Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-08-03
2003-12-30
Shaw, Shawna J. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S477000
Reexamination Certificate
active
06671540
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to methods and systems for detecting abnormalities, such as cancer and pathological conditions, in cells and tissues using optical, or spectroscopic techniques.
More specifically, the methods and apparatus of the present invention relate to the use of contrast enhancing agents in connection with optical spectroscopic techniques to distinguish abnormal or pathological tissue, such as cancerous tissue, from normal tissue and to grade and characterize cancerous tissue.
BACKGROUND OF THE INVENTION
Methods and systems for identifying abnormal or pathological cells and tissue, particularly cancer, and for diagnosing cancerous conditions, are generally time consuming and invasive. Furthermore, many of the screening techniques currently available provide limited sensitivity and specificity. Tissue biopsies or samples may be taken, fixed and examined using various histological techniques. Since these diagnostic procedures are both invasive and expensive, and they are very stressful for patients undergoing testing, it is desirable to screen areas of suspected abnormalities first, to eliminate unnecessary trauma and expense. Diagnostic screening techniques used for detecting breast cancer, uterine and cervical cancers, colon and colo-rectal cancers, esophageal cancer and skin cancers are generally inadequate and unreliable. It is thus a high priority to develop methods and systems providing reliable, non-invasive screening techniques for identifying cancer cells that have a high degree of sensitivity and specificity.
The diagnostic value of performing a biopsy is dependent upon the selection of tissue for sampling. Many pathologies are not uniformly distributed and, therefore, the selection of tissue for sampling may be determinative of the diagnostic outcome. Additionally, unnecessary removal of tissue may result in localized trauma and, in some cases, may result in diminished function. Taking tissue samples from lymph nodes, for example, is essential to assess the progression of many cancers. Yet, removal of too much tissue, or removal of normal localized tissue having a specialized function may result in diminished function. It is therefore essential to identify and sample tissue that has the highest likelihood of including pathological cells, while avoiding the removal of healthy tissue.
A primary means for treatment of pathologies, such as cancer, is surgical removal. Many studies have shown that the clinical outcome is improved when more of the total amount of tumor tissue is removed. For gross total resections of tumors, the five year survival rate is significantly increased compared to subtotal resection. Both duration of survival and independent status of the patient are prolonged when the extent of resection is maximized in cancerous tissue. Current intraoperative techniques do not provide rapid differentiation of tumor tissue from normal surrounding tissue, however, particularly after resection of the tumor begins. Development of techniques that enhance the ability to identify tumor tissue intraoperatively may result in maximizing the degree of tumor resection, thereby prolonging survival.
Most current tumor detection techniques are performed prior to surgery to provide information about tumor location. Pre-surgical imaging methods include magnetic resonance imaging (MRI) and computerized tomography (CT). In the operating room, intraoperative ultrasound and stereotaxic systems provide information about the location of tumors. Ultrasound shows the location of the tumor from the surface but, once surgery begins, ultrasound techniques do not provide information sufficient to prevent the destruction of important functional tissue while permitting maximal removal of tumor tissue. Stereotaxic systems coupled with advanced imaging techniques have, at select hospitals, provided localization of tumor margins based upon the preoperative CT or MRI scans. However, studies have shown that the location of the tumor changes, particularly during invasive surgeries, and the actual tumor may extend 2-3 cm beyond where the image enhanced putative tumor is located on preoperative images.
One method currently available for determining the location of tumors is to obtain multiple biopsies during surgery and wait for results of microscopic examination of sections. This technique, known as multiple histological margin sampling, suffers several drawbacks. First, this is a time-consuming procedure and can add about 30 to 90 minutes (depending upon the number of samples taken) to the length of time the patient is under anesthesia. The increased time required for margin sampling leads to increased medical costs, as operating room time costs are high. Moreover, increased operating room time for the patient increases the probability of infection and complications arising from the anesthesia. Multiple histological margin sampling is prone to errors, as the pathologist must prepare and evaluate samples in short order. In addition, margin sampling does not truly evaluate all regions surrounding a primary tumor and some areas of residual tumor can be missed due to sampling error.
Thus, although patient outcome is dependent upon aggressive removal of tumor tissue, a surgeon often does not have reliable intraoperative information concerning the location and extent of the tumor. Surgeons must make difficult decisions between aggressively removing tissue and destroying surrounding functional tissue, and they may not know the true outcome of the procedure until permanent tissue sections are available about one week later. Additional surgical procedures may be required following examination of the histological studies.
Other techniques developed to improve imaging of solid tumor masses during surgery include determining the shape of visible luminescence spectra from normal and cancerous tissue. U.S. Pat. No. 4,930,516 teaches that the shape of visible luminescence spectra from normal and cancerous tissue are different. Specifically, there is a shift to blue with different luminescent intensity peaks in cancerous tissue as compared to normal tissue. Thus it is possible to distinguish cancerous tissue by exciting the tissue with a beam of ultraviolet (UV) light and comparing visible native luminescence emitted from the tissue with luminescence from a non-cancerous control of the same tissue type. Such a procedure is fraught with difficulties since a real time, spatial map of the tumor location is not provided for the use of a surgeon. Moreover, the use of UV light at an excitation wavelength can cause photodynamic changes to normal cells and is dangerous for use in an operating room. In addition, UV light penetrates only superficially into tissue and requires quartz optical components instead of glass.
Following the identification and localization of malignant tissue, or following surgical removal of malignant tissue, it is important to monitor the tissue in the area of malignancy for the reappearance or spreading of malignant tissue. Similarly, monitoring an area of interest such as malignant tissue during and/or following treatment with drugs, radiation therapy, or the like, is necessary to assess the efficacy of the treatment and to monitor the progression or recession of the malignancy. Convenient, inexpensive and minimally invasive techniques are desirable for performing these monitoring functions, and few effective systems are available.
U.S. Pat. No. 5,438,989 discloses a method for imaging margins, grade and dimensions of solid tumor tissue by illuminating the area of interest with high intensity electromagnetic radiation containing a wavelength absorbed by a contrast agent, obtaining a background video image of the area of interest, administering a contrast agent, and obtaining subsequent video images that, when compared with the background image, identify the solid tumor tissue as an area of changed absorption. U.S. Pat. No. 5,699,798 discloses methods and apparatus for optically distinguishing between tumor and non-tumor tissue, and imaging mar
Benado Lisa N.
Shaw Shawna J.
Speckman Ann W.
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