Measurement Of Aortic Root In Normal Han Chinese With 3.0T Cardiac Magnetic Resonance By The Steady-State Free Precession Sequence: Feasibility,Reference Values And Influencing Factors

Objective: To measure the aortic root dimensions by 3.0T cardiac magnetic resonance(CMR)with the steady-state free precession(SSFP)sequence in normal Han Chinese people,evaluate its feasibility,provide the corresponding reference values and analyze the potential factors that may affect the aortic root dimensions.Methods: One hundred healthy Han Chinese volunteers were enrolled with 10 volunteers of each gender placed in each decile between 20 and 70 years.With the use of 3.0T CMR system both oblique sagittal and coronal Left ventricular outflow tract(LVOT)cine acquisition were scanned in these volunteers with the steady-state free precession sequence.Measurements were performed in the oblique sagittal and coronal LVOT planes.In the sagittal and coronal LVOT planes,maximum systolic and end diastolic measurements were made at the following three levels: at the aortic annulus,at the maximum diameter across the sinuses and at sinotubular junction.Thereafter,the difference between the measurements were compared.Results: From 106 volunteers scanned only 100 were enrolled in the end and the mean age of the 100 volunteers were 44.36 ± 13.82 years.The reference values in systolic and diastolic measurements of different ages and each genders were obtained.There was a difference between the systolic and diastolic diameters of the aortic root(systolic vs.diastolic),for example,the sagittal aortic root dimensions at the level of aortic annulus in systolic were larger than the corresponding values in diastole for men and women(22.11±1.65 mm vs.21.37±1.84 mm,20.87±1.45 mm vs.20.04±1.36 mm,P<0.05).There was a difference between the men's and women's measurements of the aortic root(male vs.female),for example,the sagittal aortic root dimensions at the level of aortic annulus in men were larger than the corresponding values in women both in systolic and diastole(22.11±1.65 mm vs.20.87±1.45 mm,21.37±1.84 mm vs.20.04±1.36 mm,P<0.05).There was a difference between the coronal and sagittal diameters of the aortic root(coronal vs.sagittal),for example,the aortic root dimensions at the level of aortic annulus in coronal were larger than the corresponding values in sagittal for men both in systolic and diastole(23.14±1.72 mm vs.22.11±1.65 mm,22.34±1.94 mm vs.21.37±1.84 mm,P<0.05).There was a difference among the measured values of the aortic root diameters at different ages(20-29 years vs.30-39 years vs.40-49 years vs.50-59 years vs.60-69 years),for example,the sagittal aortic root dimensions at the level of aortic annulus in the aged volunteers were larger than the corresponding values in the younger volunteers in systolic for men(21.24±1.28 mm vs.21.98±1.55 mm vs.22.11±1.44 mm vs.22.59±1.48 mm vs.22.61±1.33 mm,P<0.05).There was a difference among the different levels of the aortic root(aortic annulus vs.sinotubular junction vs.aortic sinus),for example,the sagittal aortic root dimensions were larger at the level of sinotubular junction than at the level of aortic annulus(24.24±1.75 mm vs.22.11±1.65 mm,P<0.05),and the aortic root dimensions were greater at the level of the maximum diameter across the sinuses than at the level of sinotubular junction(30.81±1.94 mm vs.24.24±1.75 mm,P<0.05)for men.The same was true for the normalized measurements of height and body surface area(P<0.05).There was a positive correlation between the dimensions of aortic root and age,as the age increased,so did the dimensions of aortic root(P<0.05).Body surface area gave a higher R2 than age for male volunteers of the aortic root dimensions in diastole(P<0.05).Conclusion:1.Measurement of aortic root in normal Han Chinese with 3.0T cardiac magnetic resonance by the steady-state free precession sequence can be feasible in the clinical practice.2.While assessing the morphological characteristics of the aortic root,we may need to make a comprehensive consideration of many potential influencing factors such as gender,age,height,body surface area,the movement of the heart,level of measurements and imaging planes which may have an effect on the measurements of the the aortic root.