Lipid-rich atherosclerotic plaques detected by gadofluorine-enhanced in vivo magnetic resonance Imaging

Background - MRI of specific components in atherosclerotic plaque may provide information on plaque stability and its potential to rupture. We evaluated gadofluorine in atherosclerotic rabbits using a new MR sequence that allows plaque detection within 1 hour after injection and assessed enhancement in lipid-rich and non - lipid-rich plaques. Methods and Results - Twelve rabbits with aortic plaque and 6 controls underwent MRI before and up to 24 hours after gadofluorine injection (50 mumol/kg). Two T1-weighted, segmented gradient-echo sequences (TFL) were compared to enhance vessel wall delineation after injection: ( 1) an inversion-recovery prepulse (IR-TFL) or ( 2) a combination of inversion-recovery and diffusion-based flow suppression prepulses (IR-DIFF-TFL). With the use of IR-TFL at 1 hour after injection, the vessel wall was not delineated because of poor flow suppression; at 24 hours after injection, the enhancement was 37% ( P < 0.01). IR-DIFF-TFL showed significant enhancement after versus before contrast ( 1 hour: 164% [ P < 0.005]; 24 hours: 207% [ P < 0.001]). At 1 hour and 24 hours after injection, the contrast-to-noise ratio was higher with the use of IR-DIFF-TFL than with IR-TFL ( 1 hour: 13.0 +/- 7.7 versus - 19.8 +/- 10.3 [ P < 0.001]; 24 hours: 15.2 +/- 5.9 versus 11.4 +/- 8.9, respectively [ P = 0.052]). There was no enhancement in the vessel wall after gadofluorine injection in the control group. A strong correlation was found (r(2) = 0.87; P < 0.001) between the lipid-rich areas in histological sections and signal intensity in corresponding MR images. This suggests a high affinity of gadofluorine for lipid-rich plaques. Conclusions - Gadofluorine-enhanced MRI improves atherosclerotic plaque detection. The IR-DIFF-TFL method allows early detection of atherosclerotic plaque within 1 hour after gadofluorine injection.