Optical spectroscopy for the detection of dysplasia in Barrett's esophagus

Clinical translational application of Raman spectroscopy to advance Benchside biochemical characterization to bedside diagnosis of esophageal diseases

Esophageal diseases result in significant mortality, morbidity, and health care costs worldwide. Current approaches to detect and monitor esophageal diseases have severe limitations. Advanced imaging technologies are being developed to complement current approaches to improve diagnostic, therapeutic and surveillance protocols in order to advance the field. Raman spectroscopy-based technologies hold promise to increase the sensitivity for detection of diseased and high-risk lesions in vitro and in vivo in real time. This technique allows for the investigation of microstructural changes and also facilitates the discovery of disease-specific biochemical alterations with the potential to provide novel insights into the pathobiology of these conditions. Raman spectroscopy has been increasingly applied in precancerous and cancerous esophageal conditions. However, its application in benign esophageal diseases is still in the early stages. Continuing its application in cancerous and precancerous conditions and expanding its use to benign esophageal disorders could lay a foundation for integration of this technology in clinical practice and diagnostic paradigms and development of an accurate and cost-effective tool for use in a clinical setting. Furthermore, Raman spectroscopy can also be used as an innovative technique to advance our understanding of the biochemical transformations associated with esophageal diseases and answer a myriad of fundamental questions in the field. In this review, we described the principles of Raman spectroscopy and instrumentation while providing an overview of current applications, challenges, and future directions in the context of esophageal diseases with an emphasis on its clinical translational application.

The color of cancer: Margin guidance for oral cancer resection using elastic scattering spectroscopy

OBJECTIVES/HYPOTHESIS

To evaluate the usefulness of elastic scattering spectroscopy (ESS) as a diagnostic adjunct to frozen section analysis in patients with diagnosed squamous cell carcinoma of the oral cavity.

STUDY DESIGN

Prospective analytic study.

METHODS

Subjects for this single institution, institutional review board-approved study were recruited from among patients undergoing surgical resection for squamous cell cancer of the oral cavity. A portable ESS device with a contact fiberoptic probe was used to obtain spectral signals. Four to 10 spectral readings were obtained on each subject from various sites including gross tumor and normal-appearing mucosa in the surgical margin. Each reading was correlated with the histopathologic findings of biopsies taken from the exact location of the spectral readings. A diagnostic algorithm based on multidimensional pattern recognition/machine learning was developed. Sensitivity and specificity, error rate, and area under the curve were used as performance metrics for tests involving classification between disease and nondisease classes.

RESULTS

Thirty-four (34) subjects were enrolled in the study. One hundred seventy-six spectral data point/biopsy specimen pairs were available for analysis. ESS distinguished normal from abnormal tissue, with a sensitivity ranging from 84% to 100% and specificity ranging from 71% to 89%, depending on how the cutoff between normal and abnormal tissue was defined (i.e., mild, moderate, or severe dysplasia). There were statistically significant differences in malignancy scores between histologically normal tissue and invasive cancer and between noninflamed tissue and inflamed tissue.

CONCLUSIONS

This is the first study to evaluate the effectiveness of ESS in guiding mucosal resection margins in oral cavity cancer. ESS provides fast, real-time assessment of tissue without the need for pathology expertise. ESS appears to be effective in distinguishing between normal mucosa and invasive cancer and between "normal" tissue (histologically normal and mild dysplasia) and "abnormal" tissue (severe dysplasia and carcinoma in situ) that might require further margin resection. Further studies, however, are needed with a larger sample size to validate these findings and to determine the effectiveness of ESS in distinguishing visibly and histologically normal tissue from visibly normal but histologically abnormal tissue.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:S1-S9, 2017.

Preoperative discrimination of benign from malignant disease in thyroid nodules with indeterminate cytology using elastic light-scattering spectroscopy

Thyroid nodules are common and often require fine needle aspiration biopsy (FNAB) to determine the presence of malignancy to direct therapy. Unfortunately, approximately 15-30% of thyroid nodules evaluated by FNAB are not clearly benign or malignant by cytology alone. These patients require surgery for the purpose of diagnosis alone; most of these nodules ultimately prove to be benign. Elastic light scattering spectroscopy (ESS) that measures the spectral differences between benign and malignant thyroid nodules has shown promise in improving preoperative determination of benign status of thyroid nodules. We describe the results of a large, prospective, blinded study validating the ESS algorithm in patients with thyroid nodules. An ESS system was used to acquire spectra from human thyroid tissue. Spectroscopic results were compared to the histopathology of the biopsy samples. Sensitivity and specificity of the ESS system in the differentiation of benign from malignant thyroid nodules are 74% and 90% respectively, with a negative predictive value of 97%. These data suggest that ESS has the potential for use in real time diagnosis of thyroid nodules as an adjunct to FNAB cytology.

Affinity peptide developed by phage display selection for targeting gastric cancer

AIM: To develop an affinity peptide that binds to gastric cancer used for the detection of early gastric cancer.

METHODS: A peptide screen was performed by biopanning the PhD-12 phage display library, clearing non-specific binders against tumor-adjacent normal appearing gastric mucosa and obtaining selective binding against freshly harvested gastric cancer tissues. Tumor-targeted binding of selected peptides was confirmed by bound phage counts, enzyme-linked immunosorbent assay, competitive inhibition, fluorescence microscopy and semi-quantitative analysis on immunohistochemistry using different types of cancer tissues.

RESULTS: Approximately 92.8% of the non-specific phage clones were subtracted from the original phage library after two rounds of biopanning against normal- appearing gastric mucosa. After the third round of positive screening, the peptide sequence AADNAKTKSFPV (AAD) appeared in 25% (12/48) of the analyzed phages. For the control peptide, these values were 6.8 ± 2.3, 5.1 ± 1.7, 3.5 ± 2.1, 4.6 ± 1.9 and 1.1 ± 0.5, respectively. The values for AAD peptide were statistically significant (P < 0.01) for gastric cancer as compared with other histological classifications and control peptide.

CONCLUSION: A novel peptide is discovered to have a specific binding activity to gastric cancer, and can be used to distinguish neoplastic from normal gastric mucosa, demonstrating the potential for early cancer detection on endoscopy.

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.

Computer-assisted analysis of abrasive transepithelial brush biopsies increases the effectiveness of esophageal screening: a multicenter prospective clinical trial by the EndoCDx Collaborative Group

BACKGROUND

The sensitivity of screening for Barrett's esophagus (BE) and esophageal dysplasia (ED) is hampered by the limited amount of tissue that can be sampled by forceps biopsy (FB).

AIM

The aim of this study was to evaluate computer assisted analysis of an abrasive, transepithelial brush biopsy as an adjunct to FB to increase detection of BE and ED.

METHODS

This was a multicenter prospective trial of patients being screened for BE and ED. Each patient had two brush biopsies (BB) and then random four-quadrant FB every 1-2 cm of the esophagus. All BB were examined with computer assistance by pathologists at CDx Laboratories (Suffern, NY), and all FB were examined by the investigators' local pathologists.

RESULTS

Of 1,266 patients enrolled, 363 were diagnosed with BE by FB alone and 146 additional cases of BE were identified by adding BB. The addition of BB to FB increased the overall detection of BE by 39.8% (95% CI 32-48%). This added detection of BE in 11.5% of all patients tested with the BB (146/1266) resulted in a number of patients needed to test (NNT) to obtain each additional positive finding of Barrett's esophagus of 8.7. Among a subset of 848 patients with gastroesophageal reflux disease and no prior history of BE, the addition of BB to FB identified an additional 105 patients with BE increasing the overall detection of BE by 70.5% (95% CI 54-90%). Dysplasia was diagnosed in 16 patients by FB alone, with an additional 14 cases detected by adding BB. The addition of BB to FB thus increased the detection of ED by 87.5%.

CONCLUSION

These results suggest that adjunctive computer-assisted analysis of an abrasive brush biopsy has the potential to substantially improve the detection of Barrett's esophagus and dysplasia in screening populations.

Elastic light-scattering spectroscopy for discrimination of benign from malignant disease in thyroid nodules

BACKGROUND

Thyroid cancer is the most common endocrine malignancy. The current standard of diagnosis, fine-needle aspiration biopsy, yields approximately 10-25% of indeterminate results leading to twice as many thyroidectomies for further diagnosis. Elastic scattering spectroscopy (ESS) is a new, minimally invasive optical-biopsy technique mediated by fiber-optic probes that is sensitive to cellular and subcellular morphological features. We assessed the diagnostic potential of ESS in the thyroid to differentiate benign from malignant thyroid nodules as determined by histology.

METHODS

Under an IRB approved protocol, 36 surgical patients (n = 21 benign thyroid nodules, n = 15 malignant tumors) had collection of ESS data from their fresh ex vivo thyroidectomy specimens. Using surgical pathology as our gold standard, spectral analyses were performed using a training set; these data were used to assess the ESS diagnostic potential using the leave-one-out technique.

RESULTS

Our test set was 75% sensitive and 95% specific in differentiating benign from malignant thyroid lesions, with a positive predictive value (PPV) of 0.92 and a negative predictive value (NPV) of 0.83.

CONCLUSIONS

The ESS can accurately distinguish benign vs malignant thyroid lesions with high PPV and NPV. With further validation ESS could potentially be used as an in situ real-time diagnostic tool or as an adjunct to conventional cytology.

Endoscopic imaging for the detection of esophageal dysplasia and carcinoma

Numerous endoscopic imaging modalities have been developed and introduced into clinical practice to enhance diagnostic capabilities. In the past, detection of dysplasia and carcinoma of the esophagus has been dependent on biopsies taken during standard white-light endoscopy. Recent important developments in biophonotics have improved visualization of these subtle lesions sufficiently for cellular details to be seen in vivo during endoscopy. These improvements allow diagnosis to be made in gastrointestinal endoscopy units, thereby avoiding the cost, risk, and time delay involved in tissue biopsy and resection. Chromoendoscopy, narrow-band imaging, high-yield white-light endoscopy, Fujinon intelligent color enhancement, and point enhancement such as confocal laser endomicroscopy are examples of enhanced imaging technologies that are being used in daily practice. This article reviews endoscopic-based imaging techniques for the detection of esophageal dysplasia and carcinoma from the perspective of routine clinical practice.