Effect of anatomy on spectroscopic detection of cervical dysplasia

Reflectance spectra analysis for mucous assessment

This review report represents an overview of research and development on medical hyperspectral imaging technology and its applications. Spectral imaging technology is attracting attention as a new imaging modality for medical applications, especially in disease diagnosis and image-guided surgery. Considering the recent advances in imaging, this technology provides an opportunity for two-dimensional mapping of oxygen saturation (SatO₂) of blood with high accuracy, spatial spectral imaging, and its analysis and provides detection and diagnostic information about the tissue physiology and morphology. Multispectral imaging also provides information about tissue oxygenation, perfusion, and potential function during surgery. Analytical algorithm has been examined, and indication of accurate map of relative hemoglobin concentration and SatO₂ can be indicated with preferable resolution and frame rate. This technology is expected to provide promising biomedical information in practical use. Several studies suggested that blood flow and SatO₂ are associated with gastrointestinal disorders, particularly malignant tumor conditions. The use and analysis of spectroscopic images are expected to potentially play a role in the detection and diagnosis of these diseases.

Dual modal spectroscopic tissue scanner for colorectal cancer diagnosis

BACKGROUND

Margin status is an important prognostic factor for treating colorectal cancer. This study aimed to investigate the usefulness of a multimodal spectroscopic tissue scanner for real-time cancer diagnosis without tissue staining.

PATIENTS AND METHODS

Diffuse reflectance spectra (DRS) and fluorescence spectra (FS) of < 1-mm-sized paired cancer and normal mucosa tissue were acquired using custom-built spectroscopic tissue scanners. For FS, we analyzed wavelengths and intensities at peaks and highest intensities near (± 1.25 nm) the known fluorescence spectral peaks of collagen (380 nm), reduced nicotinamide adenine dinucleotide (NADH, 460 nm), and flavin adenine dinucleotide (FAD, 550 nm). For DRS, we performed a similar analysis near the peaks of strong absorbers, oxyhemoglobin (oxyHb; 414 nm, 540 nm, and 576 nm) and deoxyhemoglobin (deoxyHb; 432 nm and 556 nm). Logistic regression analysis for these parameters was performed in the testing set.

RESULTS

We acquired 17,735 spectra of cancer tissues and 9438 of normal tissues from 30 patients. Intensity peaks of representative normal spectra for FS and DRS were higher than those of representative cancer spectra. Logistic regression analysis showed wavelength and intensity at peaks, and the intensities of the peak wavelength of NADH, FAD, deoxyHb, and oxyHb had significant coefficients. The area under the receiver operating characteristic curve was 0.927. The scanner had 100%, 64.3%, and 85.3% sensitivity, specificity, and accuracy, respectively.

CONCLUSIONS

The spectroscopic tissue scanner has high sensitivity and accuracy and provides real-time intraoperative resection margin assessments and should be further investigated as an alternative to frozen section.

Optical techniques for cervical neoplasia detection

This paper provides an overview of the current research in the field of optical techniques for cervical neoplasia detection and covers a wide range of the existing and emerging technologies. Using colposcopy, a visual inspection of the uterine cervix with a colposcope (a binocular microscope with 3- to 15-fold magnification), has proven to be an efficient approach for the detection of invasive cancer. Nevertheless, the development of a reliable and cost-effective technique for the identification of precancerous lesions, confined to the epithelium (cervical intraepithelial neoplasia) still remains a challenging problem. It is known that even at early stages the neoplastic transformations of cervical tissue induce complex changes and modify both structural and biochemical properties of tissues. The different methods, including spectroscopic (diffuse reflectance spectroscopy, induced fluorescence and autofluorescence spectroscopy, Raman spectroscopy) and imaging techniques (confocal microscopy, optical coherence tomography, Mueller matrix imaging polarimetry, photoacoustic imaging), probe different tissue properties that may serve as optical biomarkers for diagnosis. Both the advantages and drawbacks of these techniques for the diagnosis of cervical precancerous lesions are discussed and compared.

Intraoperative visualization of cerebral oxygenation using hyperspectral image data: a two-dimensional mapping method

PURPOSE

Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass is an important technique for cerebrovascular reconstruction. Intraoperative hemodynamic imaging is needed to perform cerebrovascular reconstruction safely and effectively. Optical intrinsic signal (OIS) imaging is commonly used for assessing cerebral hemodynamics in experimental studies, because it can provide high-resolution mapping images. However, OIS is not used clinically due to algorithm, instrumentation and spectral resolution limitations. We tested the feasibility of a hyperspectral camera (HSC) for assessment of cortical hemodynamics with spectral imaging of the cerebral cortex in rats and in vivo humans.

METHODS

A hyperspectral camera (HSC) was tested in a rat model of cerebral ischemia (middle cerebral artery occlusion) and during human revascularization surgery (STA-MCA anastomosis). Changes in cortical oxygen saturation were derived from spectral imaging data (400-800 nm) collected by exposing the cortex to Xenon light. Reflected light was sampled using the HSC. The system was then tested intraoperatively during superficial temporal artery to middle cerebral artery anastomosis procedures. Comparison with single-photon emission computed tomography (SPECT) imaging data was done.

RESULTS

During middle cerebral artery occlusion in rats, the HSC technique showed a significant decrease in cortical oxygen saturation in the ischemic hemisphere. In clinical cases, the cortical oxygen saturation was increased after STA-MCA anastomosis, which agreed with the SPECT imaging data.

CONCLUSION

Continuous collection of imaging spectroscopic data is feasible and may provide reliable quantification of the hemodynamic responses in the brain. The HSC system may be useful for monitoring intraoperative changes in cortical surface hemodynamics during revascularization procedures in humans.

Early detection of high-grade squamous intraepithelial lesions in the cervix with quantitative spectroscopic imaging

Quantitative spectroscopy has recently been extended from a contact-probe to wide-area spectroscopic imaging to enable mapping of optical properties across a wide area of tissue. We train quantitative spectroscopic imaging (QSI) to identify cervical high-grade squamous intraepithelial lesions (HSILs) in 34 subjects undergoing the loop electrosurgical excision procedure (LEEP subjects). QSI's performance is then prospectively evaluated on the clinically suspicious biopsy sites from 47 subjects undergoing colposcopic-directed biopsy. The results show the per-subject normalized reduced scattering coefficient at 700 nm (An) and the total hemoglobin concentration are significantly different (p<0.05) between HSIL and non-HSIL sites in LEEP subjects. An alone retrospectively distinguishes HSIL from non-HSIL with 89% sensitivity and 83% specificity. It alone applied prospectively on the biopsy sites distinguishes HSIL from non-HSIL with 81% sensitivity and 78% specificity. The findings of this study agree with those of an earlier contact-probe study, validating the robustness of QSI, and specifically An, for identifying HSIL. The performance of An suggests an easy to use and an inexpensive to manufacture monochromatic instrument is capable of early cervical cancer detection, which could be used as a screening and diagnostic tool for detecting cervical cancer in low resource countries.

The use of optical spectroscopy for in vivo detection of cervical pre-cancer

In order to investigate the effectiveness of optical spectroscopy for in vivo diagnosis of cervical pre-cancerous conditions, a series of published studies are surveyed. The six optical technologies investigated include fluorescence spectroscopy, reflectance spectroscopy, and their combination using point probe or multispectral imaging approaches. Searching in the well-known databases, the most recent published works were sought out. Various aspects of the studies were evaluated including the details of the technology used, the pathologic threshold for tissue classification and the gold standard, the study population and prevalence of disease in this population, the method of measurement, the number of clinicians involved in the study, the classification and validation algorithms, and the performance in terms of sensitivity, specificity and, when available, the area under the receiver operating characteristic curve. Forty-four studies conducted from 1994 to 2012 were evaluated. The data are gathered in two comprehensive tables, and five illustrations are provided to simplify a comparison between studies from different points of view. There is a broad band of studies from small pilot studies through phase III clinical trials. Among the reviewed articles, only three factors were found to influence the performance of the optical spectroscopy studies. Multispectral approaches show higher specificity than the point probe approaches (p = 0.001). The use of acetic acid before measurement and prevalence of disease among the studied population, also, have an impact on the sensitivity and specificity of the studies (p < 0.05), respectively.

Adjunctive colposcopy technologies for examination of the uterine cervix--DySIS, LuViva Advanced Cervical Scan and Niris Imaging System: a systematic review and economic evaluation

BACKGROUND

Women in England (aged 25-64 years) are invited for cervical screening every 3-5 years to assess for cervical intraepithelial neoplasia (CIN) or cancer. CIN is a term describing abnormal changes in the cells of the cervix, ranging from CIN1 to CIN3, which is precancerous. Colposcopy is used to visualise the cervix. Three adjunctive colposcopy technologies for examination of the cervix have been included in this assessment: Dynamic Spectral Imaging System (DySIS), the LuViva Advanced Cervical Scan and the Niris Imaging System.

OBJECTIVE

To determine the clinical effectiveness and cost-effectiveness of adjunctive colposcopy technologies for examination of the uterine cervix for patients referred for colposcopy through the NHS Cervical Screening Programme.

DATA SOURCES

Sixteen electronic databases [Allied and Complementary Medicine Database (AMED), BIOSIS Previews, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Database of Abstracts of Reviews of Effects (DARE), EMBASE, Health Management Information Consortium (HMIC), Health Technology Assessment (HTA) database; Inspec, Inside Conferences, MEDLINE, NHS Economic Evaluation Database (NHS EED), PASCAL, Science Citation Index Expanded (SCIE) and Science Citation Index (SCI) - Conference Proceedings], and two clinical trial registries [ClinicalTrials.gov and Current Controlled Trials (CCT)] were searched to September-October 2011.

REVIEW METHODS

Studies comparing DySIS, LuViva or Niris with conventional colposcopy were sought; a narrative synthesis was undertaken. A decision-analytic model was developed, which measured outcomes in terms of quality-adjusted life-years (QALYs) and costs were evaluated from the perspective of the NHS and Personal Social Services with a time horizon of 50 years.

RESULTS

Six studies were included: two studies of DySIS, one study of LuViva and three studies of Niris. The DySIS studies were well reported and had a low risk of bias; they found higher sensitivity with DySIS (both the DySISmap alone and in combination with colposcopy) than colposcopy alone for identifying CIN2+ disease, although specificity was lower with DySIS. The studies of LuViva and Niris were poorly reported and had limitations, which indicated that their results were subject to a high risk of bias; the results of these studies cannot be considered reliable. The base-case cost-effectiveness analysis suggests that both DySIS treatment options are less costly and more effective than colposcopy alone in the overall weighted population; these results were robust to the ranges tested in the sensitivity analysis. DySISmap alone was more costly and more effective in several of the referral groups but the incremental cost-effectiveness ratio (ICER) was never higher than £1687 per QALY. DySIS plus colposcopy was less costly and more effective in all reasons for referral. Only indicative analyses were carried out on Niris and LuViva and no conclusions could be made on their cost-effectiveness.

LIMITATIONS

The assessment is limited by the available evidence on the new technologies, natural history of the disease area and current treatment patterns.

CONCLUSIONS

DySIS, particularly in combination with colposcopy, has higher sensitivity than colposcopy alone. There is no reliable evidence on the clinical effectiveness of LuViva and Niris. DySIS plus colposcopy appears to be less costly and more effective than both the DySISmap alone and colposcopy alone; these results were robust to the sensitivity analyses undertaken. Given the lack of reliable evidence on LuViva and Niris, no conclusions on their potential cost-effectiveness can be drawn. There is some uncertainty about how generalisable these findings will be to the population of women referred for colposcopy in the future, owing to the introduction of the human papillomavirus (HPV) triage test and uptake of the HPV vaccine.

Portable optical fiber probe-based spectroscopic scanner for rapid cancer diagnosis: a new tool for intraoperative margin assessment

There continues to be a significant clinical need for rapid and reliable intraoperative margin assessment during cancer surgery. Here we describe a portable, quantitative, optical fiber probe-based, spectroscopic tissue scanner designed for intraoperative diagnostic imaging of surgical margins, which we tested in a proof of concept study in human tissue for breast cancer diagnosis. The tissue scanner combines both diffuse reflectance spectroscopy (DRS) and intrinsic fluorescence spectroscopy (IFS), and has hyperspectral imaging capability, acquiring full DRS and IFS spectra for each scanned image pixel. Modeling of the DRS and IFS spectra yields quantitative parameters that reflect the metabolic, biochemical and morphological state of tissue, which are translated into disease diagnosis. The tissue scanner has high spatial resolution (0.25 mm) over a wide field of view (10 cm × 10 cm), and both high spectral resolution (2 nm) and high spectral contrast, readily distinguishing tissues with widely varying optical properties (bone, skeletal muscle, fat and connective tissue). Tissue-simulating phantom experiments confirm that the tissue scanner can quantitatively measure spectral parameters, such as hemoglobin concentration, in a physiologically relevant range with a high degree of accuracy (<5% error). Finally, studies using human breast tissues showed that the tissue scanner can detect small foci of breast cancer in a background of normal breast tissue. This tissue scanner is simpler in design, images a larger field of view at higher resolution and provides a more physically meaningful tissue diagnosis than other spectroscopic imaging systems currently reported in literatures. We believe this spectroscopic tissue scanner can provide real-time, comprehensive diagnostic imaging of surgical margins in excised tissues, overcoming the sampling limitation in current histopathology margin assessment. As such it is a significant step in the development of a platform technology for intraoperative management of cancer, a clinical problem that has been inadequately addressed to date.

Detecting high-grade squamous intraepithelial lesions in the cervix with quantitative spectroscopy and per-patient normalization

This study develops a spectroscopic algorithm for detection of cervical high grade squamous intraepithelial lesions (HSILs). We collected reflectance and fluorescence spectra with the quantitative spectroscopy probe to measure nine spectroscopic parameters from 43 patients undergoing standard colposcopy with directed biopsy. We found that there is improved accuracy for distinguishing HSIL from non-HSIL (low grade SIL and normal tissue) when we "normalized" spectroscopy parameters by dividing the values extracted from each clinically determined suspicious site by the corresponding value extracted from a clinically normal squamous site from the same patient. The "normalized" scattering parameter (A) at 700nm, best distinguished HSIL from non-HSIL with sensitivity and specificity of 89% and 79% suggesting that a simple, monochromatic instrument measuring only A may accurately detect HSIL.

Narrow-band pass filter array for integrated opto-electronic spectroscopy detectors to assess esophageal tissue

A strategy for spectroscopy tissue diagnosis using a small number of wavelengths is reported. The feasibility to accurately quantify tissue information using only 16 wavelengths is demonstrated with several wavelength reduction simulations of the existing esophageal data set. These results are an important step for the development of a miniaturized, robust and low-cost spectroscopy system. This system is based on a sub-millimeter high-selective filter array that offers prospects for a simplified miniature spectrographic detector for a future diagnostic tool to improve the diagnosis of dysplasia. Several thin-film optical filters are optimized and fabricated and its spectral performance is shown to be sufficient for the selection of specific wavelength bands.

Domain-specific image analysis for cervical neoplasia detection based on conditional random fields

This paper presents a domain-specific automated image analysis framework for the detection of pre-cancerous and cancerous lesions of the uterine cervix. Our proposed framework departs from previous methods in that we include domain-specific diagnostic features in a probabilistic manner using conditional random fields. Likewise, we provide a novel window-based performance assessment scheme for 2D image analysis which addresses the intrinsic problem of image misalignment. Image regions corresponding to different tissue types are indentified for the extraction of domain-specific anatomical features. The unique optical properties of each tissue type and the diagnostic relationships between neighboring regions are incorporated in the proposed conditional random field model. The validity of our method is examined using clinical data from 48 patients, and its diagnostic potential is demonstrated by a performance comparison with expert colposcopy annotations, using histopathology as the ground truth. The proposed automated diagnostic approach can support or potentially replace conventional colposcopy, allow tissue specimen sampling to be performed in a more objective manner, and lower the number of cervical cancer cases in developing countries by providing a cost effective screening solution in low-resource settings.