Radiant energy – Luminophor irradiation
Reexamination Certificate
2002-09-13
2004-11-16
Porta, David (Department: 2878)
Radiant energy
Luminophor irradiation
C250S461200
Reexamination Certificate
active
06818903
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to spectroscopic methods. More particularly, in certain embodiments, the invention relates to an apparatus and methods for determining whether spectral data obtained from a region of a tissue sample are affected by one or more artifacts, such as glare, shadow, or an obstruction.
BACKGROUND OF THE INVENTION
Spectral analysis may be used to diagnose disease in tissue. For example, spectral data may be obtained during a diagnostic procedure in which spectral scans are performed on the tissue of a patient. One such diagnostic procedure is an acetowhitening procedure, in which a chemical agent is applied to tissue and the response of the tissue is captured in a spectral scan at some point following the application of the agent. The chemical agent is used, for example, to enhance the detected difference between spectral data obtained from normal tissue and spectral data obtained from abnormal or diseased tissue.
Spectral measurements of tissue may be non-representative of the actual condition of the tissue when they are affected by one or more artifacts. Artifacts include lighting artifacts such as glare or shadow, and obstructions, such as blood, a speculum, a smoke tube, or other instruments used during the procedure. Artifacts may be located and determined using visual evidence of a region of tissue at the time of the procedure. However, there are currently no other suitable methods of determining whether spectral data obtained from a region of a tissue sample are affected by an artifact. Also, current methods of obtaining spectral data do not allow for the characterization of tissue in the event an artifact adversely affects the data.
SUMMARY OF THE INVENTION
The invention provides an apparatus and methods for obtaining redundant spectral data in order to compensate for artifacts that may be present in optical sample analysis. By illuminating a region of tissue with light incident to the region at more than one angle, it is possible to obtain redundant spectral data for the region. If one set of data for a region is adversely affected by an artifact such as glare, shadow, or an obstruction, then redundant data for the region, obtained using light incident to the region at a different angle, may be useful. The redundant data may be used to describe the region of tissue, unobscured by the artifact.
The invention comprises methods for determining if spectral data obtained from a sample region are affected by an artifact, and if so, whether or not redundant data may be used in place of the affected data. Embodiments of the invention comprise the use of metrics to determine whether an artifact is affecting the spectral data from a region of a tissue sample. Methods also comprise determining what kind of artifact is affecting the data from the region. These metrics involve computations using values of the spectral data corresponding to a the region of the tissue sample. Methods of the invention do not rely on any additional visual evidence of the tissue sample, such as human visual inspection, to determine the presence or absence of an artifact. In certain embodiments, the presence of an artifact is desired. However, in preferred embodiments, the presence of an artifact is not desired, for example, because the artifact adversely affects the spectral data.
If it is determined that an artifact has rendered unusable a given set of data for a region of the sample, then the redundant data corresponding to the region may be considered. Since the redundant data is obtained using light incident to the region at a different angle from that used to obtain the affected data, the artifact may not have affected the redundant data. Multiple sets of redundant data may be used in order to compensate for one or more artifacts. Preferred methods of the invention comprise determining whether redundant data are affected by an artifact or, alternatively, whether redundant data are unaffected by the artifact and representative of the unobscured tissue. If the set of redundant data is representative of an unobscured tissue, such data may be used in place of the affected data in characterizing the region or determining the condition of the region of tissue. As mentioned above, more than one redundant set of data may be obtained. Also, if more than one set of data is determined to be unaffected by an artifact, averages of the unaffected data may be used to characterize the region of tissue.
Although specific metrics were developed for application to the analysis of in vivo cervical tissue subject to artifacts such as glare, shadow, and obstructions, methods for developing analogous metrics are also disclosed as part of the invention. Such methods may be used to create metrics for the analysis of other types of tissue such as in vivo or ex vivo colorectral, gastroesophageal, urinary bladder, lung, skin tissue, and/or any tissue comprising epithelial cells, for example. These methods may be used to create metrics for tissues that are subject to other states of health and/or other types of artifacts, in addition to those discussed herein. The invention also comprises methods of determining computational metrics for use in applications employing different types of spectral data than those specifically discussed herein.
In most embodiments discussed herein, spectral data are obtained as a function of wavelength within a range of between about 360 nm and 720 nm. However, in some embodiments, the range of wavelengths is from about 190 nm to about 1100 nm. In the methods discussed herein, where a range of about 360 nm to about 720 nm is specified, a broader range within about 190 nm and about 1100 nm is alternately used for some embodiments.
In one aspect, the invention is directed to a method of determining a condition of a region of a tissue sample using two or more sets of spectral data, each set obtained using light incident to the region at a unique angle. The method comprises the steps of: obtaining a first set of spectral data corresponding to a region of a tissue sample using light incident to the region at a first angle; obtaining a second set of spectral data corresponding to the region using light incident to the region at a second angle; selecting at least one of the two sets that is representative of the region of the tissue sample; and determining a condition of the region of the tissue sample based at least in part on a portion of the representative data.
Both the first and the second sets of spectral data comprise reflectance spectral data in some embodiments. In other embodiments, at least one of the two sets of spectral data comprises fluorescence spectral data. In some embodiments, the method further comprises obtaining one or more additional sets of spectral data corresponding to a region of interest, each set using light incident to the region at a unique angle.
The condition to be determined may be a state of health. In one embodiment the state of health comprises at least one of the following conditions: normal squamous tissue, metaplasia, Cervical Intraepithelial Neoplasia Grade I (CIN I), Cervical Intraepithelial Neoplasia Grade II (CIN II), Cervical Intraepithelial Neoplasia Grade III (CIN III), carcinoma in-situ (CIS), and cancer. In some embodiments, the state of health is a combination of two or more of the conditions above, such as Cervical Intraepithelial Neoplasia Grade II or Grade III (CIN II/III).
In another aspect, the invention is directed to a method of determining whether spectral data obtained from a region of a tissue sample are affected by an artifact. The method comprises the steps of: obtaining a first set of spectral data corresponding to a region of a tissue sample using light incident to the region at a first angle; obtaining a second set of spectral data corresponding to the region using light incident to the region at a second angle; and determining whether the first set of data is affected by an artifact based at least in part on a portion of the data from each of the two sets.
Both the first and the second sets
Flanagan John
Gao Harry
Meese Thomas
Ouradnik Michael
Schomacker Kevin T.
Medispectra, Inc.
Porta David
Sung Christine
Testa Hurwitz & Thibeault LLP
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