Jianfeng Wang

Development of a beveled fiber-optic confocal Raman probe for enhancing in vivo epithelial tissue Raman measurements at endoscopy

We report on the development of a beveled fiber-optic confocal Raman probe coupled with a ball lens for enhancing in vivo epithelial tissue Raman measurements at endoscopy. Our Monte Carlo simulations show that by selecting a proper fiber-ball lens distance and beveled angle of collection fibers, the confocal Raman probe design can be optimized for maximizing shallower tissue Raman measurements in epithelial tissue; in addition, the ratio of epithelium to stromal Raman photons collected using an optimized confocal Raman probe is approximately 19-fold higher than that using a volume-type Raman probe. Further experiments confirm that the confocal Raman endoscopic probe developed is in favor of probing superficial tissue Raman signals from a two-layer tissue phantom as well as esophagus tissue in vivo during endoscopy. This work suggests the great potential of applying the beveled fiber-optic confocal Raman probe for improving in vivo diagnosis of precancer occurring in epithelial tissue at endoscopy.

Characterizing Variability of In Vivo Raman Spectroscopic Properties of Different Anatomical Sites of Normal Colorectal Tissue towards Cancer Diagnosis at Colonoscopy

This study aims to characterize the in vivo Raman spectroscopic properties of normal colorectal tissues and to assess distinctive biomolecular variations of different anatomical locations in the colorectum for cancer diagnosis. We have developed a novel 785 nm excitation fiber-optic Raman endoscope that can simultaneously acquire in vivo fingerprint (FP) spectra (800-1800 cm(-1)) and high-wavenumber (HW) Raman spectra (2800-3600 cm(-1)) from the subsurface of colorectal tissue. We applied the FP/HW Raman endoscope for in vivo tissue Raman measurements of various normal colorectal anatomical locations (i.e., ascending colon (n = 182), transverse colon (n = 249), descending colon (n = 124), sigmoid (n = 212), and rectum (n = 362)) in 50 subjects. Partial least-squares (PLS)-discriminant analysis (DA) was employed to evaluate the interanatomical variability. The normal colorectal tissue showed a subtle interanatomical variability in molecular constituents (i.e., proteins, lipids, and water content) and could be divided into three major clusterings: (1) ascending colon and transverse colon, (2) descending colon, and (3) sigmoid and rectum. The PLS-DA multiclass algorithms were able to identify different tissue sites with varying sensitivities (SE) and specificities (SP) (ascending colon: SE: 1.10%, SP: 91.02; transverse colon: SE: 14.06%, SP: 78.78; descending colon: SE: 40.32%, SP: 81.99; sigmoid: SE: 19.34%, SP: 87.90; rectum: SE: 71.55%, SP: 77.84). The interanatomical molecular variability was orders of magnitude less than neoplastic tissue transformation. Further PLS-DA modeling on in vivo FP/HW tissue Raman spectra yielded a diagnostic accuracy of 88.8% (sensitivity: 93.9% (93/99); specificity 88.3% (997/1129) for colorectal cancer detection. This work discloses that interanatomical Raman spectral variability of normal colorectal tissue is subtle compared to cancer tissue, and the simultaneous FP/HW Raman endoscopic technique has promising potential for real-time, in vivo diagnosis of colorectal cancer at the molecular level.

Simultaneous fingerprint and high-wavenumber fiber-optic Raman spectroscopy enhances real-time in vivo diagnosis of adenomatous polyps during colonoscopy

Colorectal cancer can be prevented if detected early (e.g., precancerous polyps-adenoma). Endoscopic differential diagnosis of hyperplastic polyps (that have little or no risk of malignant transformation) and adenomas (that have prominent malignant latency) remains an unambiguous clinical challenge. Raman spectroscopy is an optical vibrational technique capable of probing biomolecular changes of tissue associated with neoplastic transformation. This work aims to apply a fiber-optic simultaneous fingerprint (FP) and high wavenumber (HW) Raman spectroscopy technique for real-time in vivo assessment of adenomatous polyps during clinical colonoscopy. We have developed a fiber-optic Raman endoscopic technique capable of simultaneously acquiring both the FP (i.e., 800-1800 cm(-1)) and HW (i.e., 2800-3600 cm(-1)) Raman spectra from colorectal tissue subsurface (<200 µm) for real-time assessment of colorectal carcinogenesis. In vivo FP/HW Raman spectra were acquired from 50 patients with 17 colorectal polyps during clinical colonoscopy. Prominent Raman spectral differences (p < 0.001) were found between hyperplastic (n = 118 spectra), adenoma (n = 184 spectra) that could be attributed to changes in inter- and intra-cellular proteins, lipids, DNA and water structures and conformations. Simultaneous FP/HW Raman endoscopy provides a diagnostic sensitivity of 90.9% and specificity of 83.3% for differentiating adenoma from hyperplastic polyps, which is superior to either the FP or HW Raman technique alone. This study shows that simultaneous FP/HW Raman spectroscopy technique has the potential to be a clinically powerful tool for improving early diagnosis of adenomatous polyps in vivo during colonoscopic examination.

Simultaneous fingerprint and high-wavenumber fiber-optic Raman spectroscopy improves in vivo diagnosis of esophageal squamous cell carcinoma at endoscopy.

This work aims to evaluate clinical value of a fiber-optic Raman spectroscopy technique developed for in vivo diagnosis of esophageal squamous cell carcinoma (ESCC) during clinical endoscopy. We have developed a rapid fiber-optic Raman endoscopic system capable of simultaneously acquiring both fingerprint (FP)(800–1800 cm−1) and high-wavenumber (HW)(2800–3600 cm−1) Raman spectra from esophageal tissue in vivo. A total of 1172 in vivo FP/HW Raman spectra were acquired from 48 esophageal patients undergoing endoscopic examination. The total Raman dataset was split into two parts: 80% for training; while 20% for testing. Partial least squares-discriminant analysis (PLS-DA) and leave-one patient-out, cross validation (LOPCV) were implemented on training dataset to develop diagnostic algorithms for tissue classification. PLS-DA-LOPCV shows that simultaneous FP/HW Raman spectroscopy on training dataset provides a diagnostic sensitivity of 97.0% and specificity of 97.4% for ESCC classification. Further, the diagnostic algorithm applied to the independent testing dataset based on simultaneous FP/HW Raman technique gives a predictive diagnostic sensitivity of 92.7% and specificity of 93.6% for ESCC identification, which is superior to either FP or HW Raman technique alone. This work demonstrates that the simultaneous FP/HW fiber-optic Raman spectroscopy technique improves real-time in vivo diagnosis of esophageal neoplasia at endoscopy.

Development of a hybrid Raman spectroscopy and optical coherence tomography technique for real-time in vivo tissue measurements.

We report on the development of a unique sideview handheld hybrid Raman spectroscopy (RS) and optical coherence tomography (OCT) technique for real-time in vivo tissue measurements. A sideview handheld RS-OCT optical probe is designed to coalign the optical paths of RS and OCT sampling arms, whereby a compact long-pass dichroic mirror (LPDM) is utilized to transmit the OCT signal through a gradient index rod lens and a reflection mirror, whereas the LPDM deflects the tissue Raman signal by 90°, leading to coaligned RS/OCT optical samplings on the tissue. Further study shows that the hybrid RS and OCT technique developed is capable of simultaneously acquiring both morphological and biochemical information about the oral tissue in vivo, facilitating real-time, in vivo tissue diagnoses and characterizations in the oral cavity.

Rapid Fiber-optic Raman Spectroscopy for Real-Time In Vivo Detection of Gastric Intestinal Metaplasia during Clinical Gastroscopy

We report a unique simultaneous fingerprint (FP) and high-wavenumber (HW) Raman spectroscopy technique coupled with a beveled fiber-optic Raman probe for improving in vivo detection of gastric intestinal metaplasia (IM)–precancerous lesions in real-time during clinical gastroscopy. A total of 4,520 high-quality in vivo FP/HW gastric Raman spectra (normal = 4,178; IM = 342) were acquired from 157 gastric patients undergoing endoscopic examination. Multivariate diagnostic algorithms based on principal components analysis and linear discriminant analysis together with the leave-one tissue site-out, cross-validation on in vivo tissue Raman spectra yield the diagnostic sensitivities of 89.3%, 89.3%, and 75.0%; specificities of 92.2%, 84.4%, and 82.0%; positive predictive values of 52.1%, 35.2%, and 28.4%; and negative predictive values of 98.9%, 98.8%, and 97.2%, respectively, by using the integrated FP/HW, FP, and HW Raman techniques for identifying IM from normal gastric tissue. Further, ROC curves generated show that the integrated FP/HW Raman technique gives the integration area under the ROC curve of 0.92 for IM classification, which is superior to either FP (0.89) or HW Raman (0.86) technique alone. This work demonstrates for the first time that the simultaneous FP/HW fiber-optic Raman spectroscopy has great potential to enhance early diagnosis of gastric precancer in vivo during routine endoscopic examination. Cancer Prev Res; 9(6); 476–83. ©2016 AACR.

Integrated Mueller-matrix near-infrared imaging and point-wise spectroscopy improves colonic cancer detection

We report the development and implementation of a unique integrated Mueller-matrix (MM) near-infrared (NIR) imaging and Mueller-matrix point-wise diffuse reflectance (DR) spectroscopy technique for improving colonic cancer detection and diagnosis. Point-wise MM DR spectra can be acquired from any suspicious tissue areas indicated by MM imaging. A total of 30 paired colonic tissue specimens (normal vs. cancer) were measured using the integrated MM imaging and point-wise MM DR spectroscopy system. Polar decomposition algorithms are employed on the acquired images and spectra to derive three polarization metrics including depolarization, diattentuation and retardance for colonic tissue characterization. The decomposition results show that tissue depolarization and retardance are significantly decreased (p<0.001, paired 2-sided Students t-test, n = 30); while the tissue diattentuation is significantly increased (p<0.001, paired 2-sided Students t-test, n = 30) associated with colonic cancer. Further partial least squares discriminant analysis (PLS-DA) and leave-one tissue site-out, cross validation (LOSCV) show that the combination of the three polarization metrics provide the best diagnostic accuracy of 95.0% (sensitivity: 93.3%, and specificity: 96.7%) compared to either of the three polarization metrics (sensitivities of 93.3%, 83.3%, and 80.0%; and specificities of 90.0%, 96.7%, and 80.0%, respectively, for the depolarization, diattentuation and retardance metrics) for colonic cancer detection. This work suggests that the integrated MM NIR imaging and point-wise MM NIR diffuse reflectance spectroscopy has the potential to improve the early detection and diagnosis of malignant lesions in the colon.

Real time near-infrared Raman spectroscopy for the diagnosis of nasopharyngeal cancer

Near-infrared (NIR) Raman spectroscopy has been investigated as a tool to differentiate nasopharyngeal cancer (NPC) from normal nasopharyngeal tissue in an ex-vivo setting. Recently, we have miniaturized the fiber-optic Raman probe to investigate its utility in real time in-vivo surveillance of NPC patients. A posterior probability model using partial linear square (PLS) mathematical technique was constructed to verify the sensitivity and specificity of Raman spectroscopy in diagnosing NPC from post-irradiated and normal tissue using a diagnostic algorithm from three significant latent variables. NIR-Raman signals of 135 sites were measured from 79 patients with either newly diagnosed NPC (N = 12), post irradiated nasopharynx (N = 37) and normal nasopharynx (N = 30). The mean Raman spectra peaks identified differences at several Raman peaks at 853 cm−1, 940 cm−1, 1078 cm−1, 1335 cm−1, 1554 cm−1, 2885 cm−1 and 2940 cm−1 in the three different nasopharyngeal conditions. The sensitivity and specificity of distinguishing Raman signatures among normal nasopharynx versus NPC and post-irradiated nasopharynx versus NPC were 91% and 95%; and 77% and 96% respectively. Real time near-infrared Raman spectroscopy has a high specificity in distinguishing malignant from normal nasopharyngeal tissue in vivo, and may be investigated as a novel non-invasive surveillance tool in patients with nasopharyngeal cancer.

Characterizing biochemical and morphological variations of clinically relevant anatomical locations of oral tissue in vivo with hybrid Raman spectroscopy and optical coherence tomography technique

This study aims to characterize biochemical and morphological variations of the clinically relevant anatomical locations of in vivo oral tissue (ie, alveolar process, lateral tongue and floor of the mouth) by using hybrid Raman spectroscopy (RS) and optical coherence tomography (OCT) technique. A total of 1049 in vivo fingerprint (FP: 800-1800 cm-1 ) and high wavenumber (HW: 2800-3600 cm-1 ) Raman spectra were acquired from different oral tissue (alveolar process = 331, lateral tongue = 339 and floor of mouth = 379) of 26 normal subjects in the oral cavity under the OCT imaging guidance. The total Raman dataset were split into 2 parts: 80% for training and 20% for testing. Tissue optical attenuation coefficients of alveolar process, lateral tongue and the floor of the mouth were derived from OCT images, revealing the inter-anatomical morphological differences; while RS uncovers subtle FP/HW Raman spectral differences among different oral tissues that can be attributed to the differences in inter- and intra-cellular proteins, lipids, DNA and water structures and conformations, enlightening biochemical variability of different oral tissues at the molecular level. Partial least squares-discriminant analysis implemented on the training dataset show that the integrated tissue optical attenuation coefficients and FP/HW Raman spectra provide diagnostic sensitivities of 99.6%, 82.3%, 50.2%, and specificities of 97.0%, 75.1%, 92.1%, respectively, which are superior to using either RS (sensitivities of 90.2%, 77.5%, 48.8%, and specificities of 95.8%, 72.1%, 88.8%) or optical attenuation coefficients derived from OCT (sensitivities of 75.0%, 78.2%, 47.2%, and specificities of 96.2%, 67.7%, 85.0%) for the differentiation among alveolar process, lateral tongue and the floor of the mouth. Furthermore, the diagnostic algorithms applied to the independent testing dataset based on hybrid RS-OCT technique gives predictive diagnostic sensitivities of 100%, 76.5%, 51.3%, and specificities of 95.1%, 77.6%, 89.6%, respectively, for the classifications among alveolar process, lateral tongue and the floor of the mouth, which performs much better than either RS or optical attenuation coefficient derived from OCT imaging. This work suggests that inter-anatomical morphological and biochemical variability are significant which should be considered as an important parameter in the interpretation and rendering of hybrid RS-OCT technique for oral tissue diagnosis and characterization.

Simultaneous fingerprint and high-wavenumber fiber-optic Raman endoscopy for in vivo diagnosis of laryngeal cancer

We report a unique simultaneous fingerprint (FP) and high-wavenumber (HW) fiber-optic confocal Raman spectroscopy for in vivo diagnosis of laryngeal cancer in the head and neck under wide-field endoscopic imaging. The simultaneous FP and HW Raman endoscopy technique was performed on 21 patients and differentiated laryngeal carcinoma from normal tissues with both sensitivity and specificity of ~85%. This study shows the great potential of the FP/HW Raman endoscopic technique developed for in vivo diagnosis of laryngeal carcinoma during routine endoscopic examination.