A program of work has been established to explore the possibility of sampling Raman information from material deeply
buried within tissues. Time-gating, spatial offsetting of source and collection (spatially offset Raman spectroscopy) and
transmission approaches have been explored. This invited contribution will outline these and the limitations of each
technique will be discussed. Time-gating allows well defined depth selection, but with low penetrations of the order of
2mm; whereas SORS has allowed some depth selection and an order of magnitude greater depth range; the use of
transmission Raman spectroscopy has permitted greater depths of penetration, but depth selection is not possible in this
configuration. To date transmission Raman has demonstrated recovery of compositional information through 27mm of
mammalian tissue. Furthermore, a first demonstration of Kerr-gated Raman spectroscopy for fluorescence suppression in
resonance Raman measurements of liver and kidney is also outlined.
Microalcifications can be found in both benign and malignant breast lesions and their composition can indicate the
disease state. Type I microcalcifications are composed of calcium oxalate dihydrate (COD) and are associated mainly
with benign tissue, whereas hydroxyapatite (HAP) can be present in both tissue types. As current practices such as
mammography and histopathology examine the morphology of the specimen, they can not reliably distinguish between
the two types of calcification, which frequently are the only mammographic features that indicate the presence of a
Analysis of tissue by Fourier transform infrared microspectroscopy (FTIR) allows biochemical information to be
achieved from the sample. Spectral maps have been carried out on paraffinized sections of breast tissue from 9 patients
of different pathology types containing calcification. The chemical composition of the calcifications and surrounding
tissue has been analysed and correlated with tissue pathology. This preliminary study has demonstrated the ability to
conduct FTIR in paraffinized sections of breast tissue, and initial observations show a correlation between HAP
carbonate substitution and tissue pathology.
It is hoped that this and further studies will give insight into how the calcifications are linked to the disease process and
will give an increased understanding of the significance of calcifications in breast tissue. If type II microcalcifications
can be differentiated in benign and malignant tissue by spectroscopic techniques, this may have positive implications in
early diagnosis if the techniques can be applied in vivo and spectroscopy of paraffin sections enables biochemical
information to accompany histopathology of the sample.
Breast calcifications can be found in both benign and malignant lesions and the composition of these calcifications can indicate the possible disease state. Calcium oxalate dihydrate (COD) is found to be associated with benign lesions, however calcium hydroxyapatite (HAP) is found mainly in malignant tissue. As current practices such as mammography and histopathology examine the morphology of the specimen, they can not reliably distinguish between the two types of calcification, which frequently are the only features that indicate the presence of a cancerous lesion. Therefore this information can be used to make a simplistic diagnostic decision, if the biochemistry of the calcifications can be probed. Studies have been performed utilising the synchrotron mid-IR beamline at Daresbury (UK) to probe the local tissue biochemistry around breast calcifications. Raman and FTIR spectroscopic analysis of the same specimen have also been performed and spectral maps have been collected of areas in and around calcifications. Principal component analysis was used to identify the major differences in the spectra across each map. FTIR and Raman spectroscopic techniques provide complementary biochemical information and demonstrate great potential for determining biochemical changes in calcified breast tissue. Further studies will be carried out using these techniques to investigate the formation mechanisms and effects of hydroxyapatite on breast tissue and to correlate the type of hydroxyapatite present to the tumour grade.