| Background Cutaneous squamous cell carcinoma(c SCC)is a malignant tumor of the skin that originates in the epidermal or accessory keratinocytes.Its pathogenesis is still unclear.The early treatment of c SCC has a good prognosis and a low recurrence rate.It is usually difficult to metastasize,and its prognosis is poor once metastasis or disease progression is accelerated.Therefore,early detection and early diagnosis of c SCC are meaningful for prognosis and survival.At present,the diagnosis of c SCC depends on histopathology,but it is accompanied by invasive,painful and affecting aesthetics,and there is the possibility of infection.Therefore,there is a need in the clinic for a technique that can perform noninvasive diagnosis of c SCC with high accuracy.In recent years,dermoscopy,optical coherence tomography(OCT),and reflectance confocal microscope have made some progress in the field of noninvasive diagnosis of skin tumors.However,the above noninvasive diagnostic techniques are based on optical imaging,which has strong scattering properties in biological tissues and thus has limited penetration depth.Acoustic imaging-based,such as high-frequency ultrasound,can provide deeper imaging depths.However,the contrast of the ultrasound signal is due to the difference in acoustic impedance of the biological tissue.Therefore,it is difficult to distinguish between tumor tissues and normal tissues having different chemical properties but similar physical properties.Photoacoustic technology is a new medical diagnostic technology based on photoacoustic effect.It combines structural and functional imaging with noninvasive and nonionizing features.It uses the specific absorption of light by various components in biological tissues to distinguish different components in the tissue,such as hemoglobin,lipids,collagen,and melanin.Photoacoustic physio-chemical spectra analysis(PAPCA)can analyze the structure and composition changes of biological tissues by combining the light sensitivity specificity of different molecules with the acoustic frequency characteristics of different microstructure sizes.At present,the existing skin imaging techniques still cannot meet the needs of early diagnosis of c SCC.PAPCA can simultaneously observe the relative content of various components in biological tissues and the heterogeneity of corresponding structures.This is very meaningful for the diagnosis of c SCC.However,the investigation on PAPCA of c SCC is still lacking now.Objective The aim was to evaluate the value of photoacoustic physio-chemical spectra analysis in the diagnosis of c SCC.Methods In the mouse skin tumor model PAPCA study,SKH-1 mouse c SCC modeling using SS-03 B solar simulator.The multi-spectral photoacoustic signal was collected from the mouse c SCC tissue using the PAPCA detection system.The p Welch function was used to time-frequency convert the photoacoustic data,the power spectrum of the signal was calculated,and the PAPCA of the detected tissue was drawn.The photoacoustic power spectrum at a specific wavelength is selected,linearly fitted in a specific acoustic frequency range,the fitting parameters are extracted,and the tumor and normal tissues are quantitatively analyzed.The tissues were examined for H&E staining,Fontana-Masson melanin staining,Masson collagen staining,CD31 immunohistochemical staining and Nile red fluorescence staining to observe tumor structure,melanin,collagen,blood vessels and lipids.The pathological results were compared with the statistical results of the fitted parameters.Further,PAPCA of 15 human c SCC was performed by the above method.Results PAPCA of mouse and human c SCC were obtained.The results of the mouse model and the ex vivo tissue study show that the analysis of the fitting parameters(slope,intercept)obtained by quantifying the PAPCA can well reflect the microstructure and compositional differences of the tissue.In the mouse model of c SCC,compared with normal skin tissue,the fitting slope of mouse c SCC at 690 nm compared with normal skin tissue(p>0.05),and the intercept was significantly increased(p<0.05).The fitting slope was significantly increased at 750 nm(p<0.05),and the intercept was not statistically different(p>0.05).The fitting slope at 1600 nm was significantly increased(p<0.05)and the intercept was significantly decreased(p<0.05).At 1730 nm,the fitting slope was significantly increased(p<0.01)and the intercept was significantly decreased(p<0.01).The results suggest that the heterogeneity of mouse c SCC is higher,the content of lipid and collagen in tissues is decreased,and the content of hemoglobin is increased,which is consistent with pathological results.The results of human c SCC in vitro showed that there was no significant difference in c SCC photoacoustic fitting slope and intercept at 690 nm compared with normal skin tissue(p>0.05).The fitting slope was significantly increased at 850 nm(p<0.05),and the intercept was not statistically different(p>0.05).The fitting slope was significantly increased at 1370 nm(p<0.01),and the intercept was significantly decreased(p<0.01).The fitting slope was significantly increased at 1400 nm(p<0.01),and the intercept was significantly decreased(p<0.05).The results showed that the heterogeneity of c SCC tissue was higher,the content of lipid and collagen in the tissue decreased,and the content of melanin and hemoglobin did not change significantly,which was consistent with the pathological results and the experimental results of the mouse model.Conclusion This study initially established a photoacoustic detection method for c SCC,and the results showed that PAPCA of c SCC is consistent with histopathology.It provides new ideas for the early diagnosis and evaluation of skin cancer. |
PDF Full Text Request