High wavenumber Raman spectroscopy for in vivo detection of cervical dysplasia

Abstract

Raman spectroscopy is a vibrational spectroscopic technique capable of optically probing the biomolecular changes associated with neoplastic transformation. The purpose of this study was to apply near-infrared (NIR) Raman spectroscopy in the high wavenumber (HW) region (2800-3700 cm(-1)) for in vivo detection of cervical dysplasia. A rapid-acquisition NIR Raman spectroscopy system associated with a ball-lens fiber-optic Raman probe was developed for in vivo spectroscopic measurements at 785 nm excitation. A total of 92 in vivo HW Raman spectra (46 normal, 46 dysplasia) were acquired from 46 patients with Pap smear abnormalities of the cervix. Significant difference in Raman intensities of prominent Raman bands at 2850 and 2885 cm(-1) (CH(2) stretching of lipids), 2940 cm(-1) (CH(3) stretching of proteins), and the broad Raman band of water (peaking at 3400 cm(-1) in the 3100-3700 cm(-1) range) were observed in normal and dysplasia cervical tissue. The diagnostic algorithms based on principal components analysis and linear discriminant analysis together with the leave-one-patient-out cross-validation method on in vivo HW Raman spectra yielded a diagnostic sensitivity of 93.5% and specificity of 97.8% for dysplasia tissue identification. This study demonstrates for the first time that HW Raman spectroscopy has the potential for the noninvasive, in vivo diagnosis and detection of precancer of the cervix.