Vibrational Spectroscopy in Vascular Disease

Spectroscopy, more specifically Raman spectroscopy, has the ability to give in vivo recordings of chemical compositions of atheromatous plaques. 

The initial work in this field consisted of in vitro work carried out on human vessels. Early work centred on fluorescence spectroscopy. Bartorelli and coworkers (1991) and Richards-Kortum and colleagues (1989) studied the use of spectra in the ultraviolet (UV) light region on diseased arterial tissue. They independently demonstrated the ability of this technique to distinguish between atheromatous and normal tissue. However, recent work has centred on the use of Raman as this has an ability to distinguish different chemical compositions. Raman spectra are unique to compounds (which produce fingerprints as stated above) whereas fluorescence spectra are limited in their differences. 

Their results indicated that non-atherosclerotic tissue, non-calcified atherosclerotic plaque and calcified atherosclerotic plaque all give different Raman spectra, and hence this technique can differentiate these three states of a vessel wall. Microscopic Raman spectra were obtained to study the chief constituents of the vessels under examination elastic laminae, collagen fibres, smooth muscle cells, fat cells, foam cells, necrotic cores, cholesterol crystals, p-carotene containing crystals, and calcium mineralisations. The results indicate different levels of each depending on which arterial sample was being observed. For example, calcified atherosclerotic plaques contained a lot more foci of calcium 

Motz and colleagues (2006) used their Raman probe in vivo approximately two years later. Spectra were taken from 14 femoral bypass and 6 carotid endarterectomy operations. The sites from which spectra were taken were 

The other practical issue is that all lights have to be turned off in theatre to reduce background noise this may not be appropriate or even safe in all circumstances. 

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