Nuclear Magnetic Resonance Microscopy of Atheroma in Human Coronary Arteries

Abstract

The purpose of this study was to use direct nuclear magnetic resonance (NMR) microscopy to quantitate and image accumulations of atheroma lipids in human coronary arteries and to validate the results by comparison with histologic preparations. NMR microscopy was performed on a superconducting experimental NMR imaging system operating at 2 Tesla with a probe designed for short echo time (TE), strong B1 field strength, and small samples. Data acquisition used multiple-offset chemical encoding with offsets based on the thermotropic spectral signature of atheroma lipids within the human arterial vessel wall. Three separate channels of image data yielded color axis display of atheroma within the vessel walls. Atheroma location by histology was identified by rarefaction of stroma, as the lipids are extracted in the process of embedding in paraffin. Perimeters, areas, and a shape index (perimeter2:4 pi area) of lumen, atheroma, and outer wall were determined and compared for NMR vs histology. There was no significant difference in the measurements with the exception of luminal shape indices, which were uniformly larger by histology, attributable to flattening of the vessels during histologic preparation. NMR measurement of atheroma content of coronary artery walls agreed well with histology (r = 0.996). NMR microscopy with color axis display proved able to quantitate and image atheroma in coronary arteries, obviating the distortions and lipid removal associated with fixation, embedding, and sectioning for histology.