Spectral region optimization for Raman-based optical biopsy of inflammatory lesions.
OBJECTIVE
The biochemical alterations between inflammatory fibrous hyperplasia (IFH) and normal tissues of buccal mucosa were probed by using the FT-Raman spectroscopy technique. The aim was to find the minimal set of Raman bands that would furnish the best discrimination.


BACKGROUND
Raman-based optical biopsy is a widely recognized potential technique for noninvasive real-time diagnosis. However, few studies had been devoted to the discrimination of very common subtle or early pathologic states as inflammatory processes that are always present on, for example, cancer lesion borders.


METHODS
Seventy spectra of IFH from 14 patients were compared with 30 spectra of normal tissues from six patients. The statistical analysis was performed with principal components analysis and soft independent modeling class analogy cross-validated, leave-one-out methods.


RESULTS
Bands close to 574, 1,100, 1,250 to 1,350, and 1,500 cm(-1) (mainly amino acids and collagen bands) showed the main intragroup variations that are due to the acanthosis process in the IFH epithelium. The 1,200 (C-C aromatic/DNA), 1,350 (CH(2) bending/collagen 1), and 1,730 cm(-1) (collagen III) regions presented the main intergroup variations. This finding was interpreted as originating in an extracellular matrix-degeneration process occurring in the inflammatory tissues. The statistical analysis results indicated that the best discrimination capability (sensitivity of 95% and specificity of 100%) was found by using the 530-580 cm(-1) spectral region.


CONCLUSIONS
The existence of this narrow spectral window enabling normal and inflammatory diagnosis also had useful implications for an in vivo dispersive Raman setup for clinical applications.
de Carvalho
Luis Felipe das Chagas E Silva
LF
Departamento de Biociências e Diagnóstico Bucal, Faculdade de Odontologia de São José dos Campos-FOSJC, Brazil.
Bitar
Renata Andrade
RA
Arisawa
Emília Angela Loschiavo
EA
Brandão
Adriana Aigotti Haberbeck
AA
Honório
Kathia Maria
KM
Cabral
Luiz Antônio Guimarães
LA
Martin
Airton Abrahão
AA
Martinho
Herculano da Silva
Hda S
Almeida
Janete Dias
JD
D002610:Cheek / Q000473:pathology; D007249:Inflammation / Q000473:pathology*; D009061:Mouth Mucosa / Q000737:chemistry / Q000166:cytology / Q000473:pathology*; D010363:Pattern Recognition, Automated; D025341:Principal Component Analysis; D012680:Sensitivity and Specificity; D013059:Spectrum Analysis, Raman / Q000379:methods; D014732:Vibration