Simultaneous Fingerprint and High-Wavenumber Confocal Raman Spectroscopy Enhances Early Detection of Cervical Precancer In Vivo

Abstract

Raman spectroscopy is a vibrational spectroscopic technique capable of nondestructively probing endogenous biomolecules and their changes associated with dysplastic transformation in the tissue. The main objectives of this study are (i) to develop a simultaneous fingerprint (FP) and high-wavenumber (HW) confocal Raman spectroscopy and (ii) to investigate its diagnostic utility for improving in vivo diagnosis of cervical precancer (dysplasia). We have successfully developed an integrated FP/HW confocal Raman diagnostic system with a ball-lens Raman probe for simultaneous acquistion of FP/HW Raman signals of the cervix in vivo within 1 s. A total of 476 in vivo FP/HW Raman spectra (356 normal and 120 precancer) are acquired from 44 patients at clinical colposcopy. The distinctive Raman spectral differences between normal and dysplastic cervical tissue are observed at ~854, 937, 1001, 1095, 1253, 1313, 1445, 1654, 2946, and 3400 cm(-1) mainly related to proteins, lipids, glycogen, nucleic acids and water content in tissue. Multivariate diagnostic algorithms developed based on partial least-squares-discriminant analysis (PLS-DA) together with the leave-one-patient-out, cross-validation yield the diagnostic sensitivities of 84.2%, 76.7%, and 85.0%, respectively; specificities of 78.9%, 73.3%, and 81.7%, respectively; and overall diagnostic accuracies of 80.3%, 74.2%, and 82.6%, respectively, using FP, HW, and integrated FP/HW Raman spectroscopic techniques for in vivo diagnosis of cervical precancer. Receiver operating characteristic (ROC) analysis further confirms the best performance of the integrated FP/HW confocal Raman technique, compared to FP or HW Raman spectroscopy alone. This work demonstrates, for the first time, that the simultaneous FP/HW confocal Raman spectroscopy has the potential to be a clinically powerful tool for improving early diagnosis and detection of cervical precancer in vivo during clinical colposcopic examination.

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

“…The enhanced metabolic rate in colonic cancer [36] contributes to the increased water content as water provides the conversion of mechanical energy developed by contractile proteins into the chemical energy useful in cell process [37]. The increased water for the cancerous colonic tissue has also been observed in other cancer tissues (e.g., esophagus [28], stomach [38], cervix [39][40][41] and brain [42]) by using Raman spectroscopy [4,28,[38][39][40][41][42]. We have also found the decreased DR of hemoglobin band (940 nm) for the colonic cancer, signifying the increased hemoglobin content associated with colonic cancer tissue.…”

Raman spectroscopy for screening and diagnosis of cervical cancer

“…In vivo applications are reliant on the further development of spectroscopic probes, which have already been demonstrated for cervical applications [44][45][46][47][48][49][50]. Raman spectroscopy could be a potential candidate for an adjunct tool for 'screen and treat' approaches for low resource countries.…”

Development of a multiplexing fingerprint and high wavenumber Raman spectroscopy technique for real-timein vivotissue Raman measurements at endoscopy

“…4,6 Recent reports have shown that high wavenumber (HW) (i.e., 2800 to 3700 cm −1 ) Raman spectroscopy also contains valuable biomolecular information that can advantageously be used for diagnostic purposes. [1][2][3][4]8,9 The use of HW Raman spectroscopy is appealing due to the relatively intense tissue Raman signals generated (CH 2 and CH 3 moiety stretching vibrations of protein and lipids, OH stretching vibrations of water), as well as the considerably reduced fused silica fiber interferences and tissue autofluorescence that may allow a better assessment of the genuine tissue Raman signals. 2,9 Our study has established that the integrated FP and HW Raman technique offers complimentary diagnostic information for increasing the accuracy and robustness of detecting precancer in cervical tissue.…”

“…2,9 Our study has established that the integrated FP and HW Raman technique offers complimentary diagnostic information for increasing the accuracy and robustness of detecting precancer in cervical tissue. 8 To date, only a very limited clinical work has been reported on the tissue Raman measurements covering both the FP and HW regions. The tissue Raman signals are measured either by successively switching the different laser excitation frequencies or by rotating the gratings for each spectral region, 1,8 which are not suitable for rapid in vivo measurements in clinical endoscopic settings.…”

“…8 To date, only a very limited clinical work has been reported on the tissue Raman measurements covering both the FP and HW regions. The tissue Raman signals are measured either by successively switching the different laser excitation frequencies or by rotating the gratings for each spectral region, 1,8 which are not suitable for rapid in vivo measurements in clinical endoscopic settings. In this letter, we report on the development of a novel multiplexing Raman spectroscopic technique that can simultaneously acquire both FP and HW in vivo tissue Raman spectra with high spectral resolution during endoscopy.…”