Atherosclerotic plaque characterization by NMR spectroscopy

Abstract

Background: High resolution Magnetic Resonance Spectroscopy (MRS) in vitro was used to investigate the correlation between the chemical composition of atheromatous plaques and their stability (vulnerability to rupture) which is of fundamental importance and is a rather controversial point in literature.

Methods: In this study five tissues were collected from ex vivo human abdominal aortas and divided in three groups according to their atherosclerotic lesion using the American Heart Association Committee on Vascular Lesions. Due to the semi-solid nature of the plaques, Magic Angle Spinning (MAS) and heteronuclear Decoupling (DEC) were used to acquire six ¹³C spectra with appreciable high resolution for five samples and the solvent. The ¹H high resolution spectra also were obtained for the same samples.

Results: The most common fatty acids present in the samples were identified and also the relative amounts of polyunsaturated (PUFA), unsaturated (UFA) and saturated fatty acids associated with the progress of the deterioration process of atheromatous plaques.

Conclusions: NMR results show that the lipidic composition of atheromatous plaque evolves from a state with high levels of PUFA and UFA for a subject with lower classification to a new state containing, 6 and 4 times less unsaturated fatty acids respectively than those subjects with more stenotic lesions. In addition, average rate of conversion of PUFA to UFA is approximately two times higher in more stenotic lesions. These results suggest that the lipidic components of atheromatous plaque can be related to its vulnerability to rupture, which clearly demonstrate the importance of the method to study this disease.