Figure 10. AFM images of COM and Raman spectra (selected spots) adsorbed p-OPN on COM faces.[251] Copyright © 2012 American Chemical Society.
Tumor tissue microcalcifications
Tumor tissue microcalcifications are classified into two types: Type I is calcium oxalate dihydrate, and Type II is hydroxyapatite.[252] Type I microcalcifications are diagnosed as benign, while Type II is considered malignant. The overall biochemical composition of the microcalcifications was used to differentiate the malignancy of the tumor tissue.[136] It is noteworthy that these tumor microcalcifications are usually seen in breast cancer and that more mineral crystals increase with time.[74] Tissue microcalcifications were also found in chondrogenic tumors and human skin pilomatrixoma.[253,254]
Coherent anti-stokes Raman spectroscopy was used to image breast cancer tissue based on differences in microcalcifications types.[134] Hyperspectral stimulated Raman scattering spectroscopy(SRS) was used to enhance the imaging sensitivity and resolution of tumor microcalcifications, which improved the accuracy of benign and malignant tumor classification to 98.21% with the synergy of a support vector machine (SVM) based classification algorithm (Figure 11 ).[66,255] Alternatively, imaging and diagnosis of tumor microcalcifications can be achieved by introducing shell-isolated nanoparticle-enhanced Raman scattering (SHINERS) probes.[256] In addition to the improvement and enhancement of detection methods, the study of classification algorithms, with examples like decision tree classification, k-nearest neighbor (k-NN), SVM analysis, PCA, and LDA, is also crucial.[67,257]