Purpose: To assess the potential role of intravascular magnetic resonance (MR) imaging with receiver coils mounted to an inflatable balloon in characterizing atherosclerotic plaque.
Materials and methods: Twelve human harvested segmental femoral arteries with atherosclerotic changes were studied with a 5-F imaging balloon catheter equipped with a single-loop wire receiver coil. Imaging was performed with an open-configuration 0.5-T (n = 6) or a 1.5-T (n = 6) MR system, with T1- and T2-weighted sequences. Histologic analysis was the reference standard, and MR images were analyzed with regard to vessel wall thickness, plaque area, and components.
Results: Images acquired at 1.5 T were characterized by better in-plane resolution (117 x 104 microm). Resolution at 0.5 T (234 x 178 microm) was sufficient to discriminate the wall layers. On T2-weighted images, adventitia, media, and thickened intima could be discriminated. T1-weighted images did not permit differentiation between wall layers. There was good correlation between MR and histologic measurements of wall thickness (r = .97) and plaque area (r = .98). Plaque characterization was possible on T2-weighted images. Calcified plaque was identified as areas of low signal intensity (134 +/- 98) and could be differentiated from fibrous structures containing collagen (1,968 +/- 680) or fatty components (762 +/- 394).
Conclusion: Intravascular MR imaging on the basis of the balloon catheter design enables differentiation of wall layers and plaque components.