Caroline Jung, Presenter: Nothing to Disclose

Sabine Christiansen, Abstract Co-Author: Nothing to Disclose

Michael Gerhard Kaul, Abstract Co-Author: Nothing to Disclose

Markus Heine, Abstract Co-Author: Nothing to Disclose

Harald Ittrich MD, Abstract Co-Author: Nothing to Disclose

Gerhard B. Adam MD, Abstract Co-Author: Nothing to Disclose

The aim of this study was to quantify atherosclerotic plaque by volumetric assessment and by determining T1 Relaxivity at 7T MRI using Gadospin F (GDF) in comparison to en face measurements.

Mice (n=5 for each group) were set on high fat diet (HFD) at 9 weeks of age. In-vivo MRI of the aortic vessel wall was performed at 9, 13, 17 and 21 weeks after commencement of the HFD. Therapy group was reswitched to normal rodent diet 13 weeks after starting HFD and monitored by MRI for 12 weeks. ApoE-/- and control mice were imaged before and two hours after i.v. injection of GDF (dosage: 100 µmol/kg) at a small animal MRI at 7T (Clinscan, Bruker). MRI was performed using a 3D Inversion Recovery Gradient echo MR sequence (TR/TE 650/2 ms, TI 250ms; FA 20°; NSA 6, matrix 196 x 196, 64 slices, slice thickness 180µm; TA 9min, eff. voxel resolution (180 µm)3 in transverse orientation covering the thoracic aorta. In same slice orientation T1 Mapping was performed using Saturation Recovery sequences. Subsequently, mice were killed for en face preparation. MR image analyses were performed using ImageJ (V. 1.44p, NIH, USA). Total plaque volume (TPV), total plaque volume relative to the examined area of the aorta (rTPV) and T1 Relaxivity were estimated. Pearson correlation between MRI and en face measurements was analysed.

MRI and en face analyses showed an exponential increase of TPV, rTPV and T1 relaxivity over time, which showed a slower and linear increase for therapy group. A good correlation (r=0.74; p<0.001) for TPV between MRI and en face measurements was observed which was even stronger estimating the rTPV (r=0.89; p<0.001). A correlation of r=0.71 (p<0.001) was achieved between T1 relaxivity and TPV en face measurements, while only a correlation of r=0.57 (p<0.01) was found between rTPV in en face measurements and T1 relaxivity. In control mice no plaque volume was observed. A moderate but not significant correlation was found for body weight and cholesterol and triglyceride level (r>0.7 and r>0.8, respectively).

GDF-enhanced MRI showed a moderate to strong correlation between measured plaque volume and T1 Realxivity in vivo and typical en face measurements ex vivo.

GDF-enhanced in vivo MRI is a powerful noninvasive imaging technique allowing reliable estimation of plaque burden, monitoring of disease progression and evaluation of therapy response in preclinical studies.

Jung, C, Christiansen, S, Kaul, M, Heine, M, Ittrich, H, Adam, G, Quantifying Progression and Regression of Atherosclerosis in ApoE-/- Mice Using Gadospin F at 7T MRI: Comparison of Volumetric Method and T1 Relaxivity to en Face Measurements  .  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14016938.html