Contrast enhanced magnetic resonance imaging in early assessment of atherosclerotic lesion of abdominal aortic wall and common iliac arteries

Abstract

Highlights. Early atherosclerotic changes in the abdominal aortic wall and common iliac arteries in patients without clinical manifestations of critical atherosclerotic stenosis of the lower extremity arteries were studied using contrast enhanced magnetic resonance imaging. A method for quantitative characterization of the accumulation of paramagnetic contrast in the abdominal aortic wall and common iliac arteries is presented.Aim. To study the pattern of early atherosclerotic lesions of the abdominal aortic wall and common iliac arteries in patients without clinical manifestations of critical atherosclerotic stenosis of the lower extremity arteries using paramagnetic contrast enhancement (CE-) MRI.Methods. The retrospective study included 36 patients (25 men, 11 women) who underwent MRI of the lumbar spine with CE, without signs of atherosclerosis of the lower extremities. Subsequently, 2.5 and 4 years after CE-MRI, two patients developed acute leg ischemia and required vascular surgeries. At the time of the study, both had higher levels of C-reactive protein in the blood (6.3 mg/L and 5.9 mg/L, while the other patients had <4.2 mg/L). MRI included T2 – and T1-weighted spin-echo scans (T2-w and T1-w) in the axial and sagittal planes, before and in 10-15 minutes after contrast injection. The index of enhancement (IE) of T1-w was calculated based on the ratio of mean intensities of the region of arterial wall over aorta and iliac arteries in CE-MRI and pre-contrast MRI: IE = Int.T1–w. CE / Int. T1–w pre-contrast.Results. Depending on the IE of the abdominal aortic wall in CE-MRI, patients were divided into three groups: group 1 (n = 11) with IE ≤1.05; group 2 (n = 16) with 1.05 <IE ≤1.15; group 3 (n = 9) with IE >1.15. The aortic IE in all three groups was 1,03 (1,01;1,03); 1,10 (1,09;1,15); 1,36 (1,16;1,40) respectively (p<0.001). The thickness of the abdominal aortic wall progressively increased moving up the group 1, while statistically significant differences were found only between the groups 1 and 3, and the groups 2 and 3 (p<0.001). There were no differences in the wall thickness of the common iliac arteries and the diameter of all vessels studied between the groups. Two patients from the group 3 later presented with acute limb ischemia.Conclusion. The state of the abdominal aortic wall and common iliac arteries should be evaluated, and IE of T1-w should be calculated when performing CE-MRI examination of the area of the descending aorta to assess pathological neoangiogenesis as the most important component of atherogenesis.