Quantitative and qualitative estimation of atherosclerotic plaque burden in
vivo at 7T MRI using Gadospin F in comparison to en face preparation evaluated
in ApoE KO
Background The aim of the study was to quantify atherosclerotic plaque burden
by volumetric assessment and T1 relaxivity measurement at 7T MRI using
Gadospin F (GDF) in comparison to en face based measurements. Methods and
results 9-weeks old ApoE-/- (n = 5 for each group) and wildtype mice (n = 5)
were set on high fat diet (HFD). Progression group received MRI at 9, 13, 17
and 21 weeks after HFD initiation. Regression group was reswitched to chow
diet (CD) after 13 weeks HFD and monitored with MRI for 12 weeks. MRI was
performed before and two hours after iv injection of GDF (100 μmol/kg) at 7T
(Clinscan, Bruker) acquiring a 3D inversion recovery gradient echo sequence
and T1 Mapping using Saturation Recovery sequences. Subsequently, aortas were
prepared for en face analysis using confocal microscopy. Total plaque volume
(TPV) and T1 relaxivity were estimated using ImageJ (V. 1.44p, NIH, USA). 2D
and 3D en face analysis showed a strong and exponential increase of plaque
burden over time, while plaque burden in regression group was less pronounced.
Correspondent in vivo MRI measurements revealed a more linear increase of TPV
and T1 relaxivity for regression group. A significant correlation was observed
between 2D and 3D en face analysis (r = 0.79; p<0.001) as well as between 2D /
3D en face analysis and MRI (r = 0.79; p<0.001; r = 0.85; p<0.001) and delta
R1 (r = 0.79; p<0.001; r = 0.69; p<0.01). Conclusion GDF-enhanced in vivo MRI
is a powerful non-invasive imaging technique in mice allowing for reliable
estimation of atherosclerotic plaque burden, monitoring of disease progression
and regression in preclinical studies