Identification of high-risk atherosclerotic plaques: a survey of spectroscopic methods.

It is likely that some form of spectroscopy—magnetic resonance, Raman, fluorescence, or diffuse reflectance— will occupy a prominent place among the new diagnostic techniques required to identify nonstenotic, high-risk coronary plaques that are prone to disruption. While angiographic imaging has been very useful for decision making in the treatment of patients with coronary artery disease, it is not useful for the identification of vulnerable plaque. Nuclear magnetic resonance (NMR) imaging, intravascular ultrasound (IVUS), and optical coherence tomography are several of the methods being advocated for vulnerable plaque detection. These techniques are based on the concept that visual reconstruction of the microanatomy of the plaque will provide enough information to detect plaque vulnerability for disruption. Other methods like elastography and thermography are advocated to identify surrogates of vulnerability, like the biomechanics properties and the temperature gradient of the plaque. Spectroscopy is based on the analysis of electromagnetic spectra induced by light and provides direct evaluation of plaque composition, which in turn should yield the needed information about vulnerability.