| ObjectiveTo explore the influence factors on enhanced effect of contrast material in 64-slice spiral CT coronary angiography: weight, heart rate, BMI, CO and EF. To optimize the contrast material injection scheme, explore feasibility of decreasing contrast material dose and the rate of injection, in order to decrease the harm to patient.Materials and MethodsThree hundred sixty consecutive patients undergoing coronary angiography by 64-slice CT were divided into six groups, namely group A1(included 41 patients), group A2(included 54 patients), group B1(included 75 patients), group B2(included 107 patients), group C1(included 37 patients),group C2(included 46 patients). Patients in group A1 and A2 were less than 60kg, patients in group B1 and B2 were less than 75kg and heavier than 60kg, patients in group C1 and C2 were less than 90kg and heavier than 75kg. A1,B1,C1 are the standard groups and A2,B2,C2 are the optimize strategy groups. Groups A1,B1,C1 were injected 60ml contrast material with speed of 5.0ml/s. Group A2 was injected 42ml contrast material with speed of 3.5ml/s. Group B2 was injected 48ml contrast material with speed of 4.0ml/s. Group C2 was injected 54ml contrast material with speed of 4.5ml/s. Computed tomography densities (Hounsfield units) in ascending aorta, descending aorta, and main pulmonary artery, left main coronary, left ventricle was measured three times and computed the mean enhancement value. Statistical analysis: (1)The body weight, heart rate, BMI, CO, EF and the attenuation of the ascending aorta were analyzed by multiple linear regression analysis. The body weight, CO and the attenuation of ascending aorta were assessed with Pearson correlate analysis. The heart rate and the attenuation of ascending aorta were assessed with Pearson correlate analysis in the group of 60 to 70kg. (2) Compared the contrast material dose, the rate of injection and the enhanced effect in group A1 and A2, group B1 and B2, group C1 and C2. To prove the feasibility of the optimize strategy.Results(1)The result of multiple linear regression analysis was: Mean=829.962-5.324 Weight+5.253BMI-1.648 Heart rate-0.013CO(F=48.253, P=0.000). The influence from high to low was: weight (-0.851), BMI (0.209), heart rate (0.173) and CO (-0.169). A significant negative correlation was found between weight and attenuation (r=-0.665, P<0.01). CO and the attenuation of ascending aorta had low negative correlation(r=-0.355,P<0.01). Similarly, a significant low correlation was found between the heart rate and the attenuation of ascending aorta had significant negative correlation in the group of 60kg to 70kg(r=-0.268,P<0.05). (2)Image quality score statistical analysis: image quality score results had no statistical difference(P>0.05) by Mann-Whitney U-test. The enhancement effect had no differences. The mean CT values statistical analysis: The mean CT values of the ascending aorta, descending aorta, and left main coronary had statistical differences(P<0.05)byχ2-test, there were no differences between standard groups and the optimize strategy groups. The mean CT values of left ventricle in group A1 and A2, group B1 and B2 had no statistical differences(P>0.05) byχ2-test, but in group C1 and C2 had statistical difference(P<0.05)byχ2-test. Group C1 less than group C2 for the enhancement values of left ventricle. The mean CT values of pulmonary artery of two groups had no statistical difference(P>0.05) by t-test.Conclusions(1) Provided the same dosage of contrast material, the critical influence factor on enhanced effect of contrast material is weight, following by BMI, heart rate, and CO. There is a negative correlation between weight and enhanced effect, while no correlation between EF and enhanced effect. (2) Combined with reasonable scan technology, can decrease contrast material dose and the rate of injection according to weight, in CTCA examination, in order to decrease the harm to patient. So the optimize strategy groups are valuable and feasible in 64-slice spiral CT coronary angiography. |
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