Low Radiation and Contrast Medium Dose in 64- Slices Multidtector Ct Angiography of Thoracic Aorta

Abstract

Abstract. The evaluation of chronic aortic diseases, many protocols of low radiation dose and low medium iodine contrast dose are performed. The main aim of this study is to give a preliminary evaluation of dose reduction and iodine dose reduction. In our hospital, from February 2013 to November 2016 we selected 150 patients divided into two groups: 60 for our study and a control group of 90 cases. All CT examinations were performed with a 64-MDCT scan (Optima-CT GE Healtcare). Tube voltage was reduced in our study (80 kVp versus 120 in our standard) with automated current modulation system in both groups. Concerning the iodine dose reduction, in the study groups it was strongly reduced (40 cc of 370 mg/ml versus 90 cc of 370 mg/ml): a mechanical power injector was used to administer the contrast material via catheters (20-gauge) placed in the antecubital vein at a flow rate of 4.5 ml/sec. Two radiologists qualitatively graded the image quality of all cases, defining the walls and the enhancement of the lumen of the aorta. On the basis of the criteria reported in the literature, a five-point subjective scale was used to grade image quality, from excellent (1) to non-diagnostic quality (5). The reasons for the degraded image quality were due to high BMI and consisted especially in low signal/noise ratio, and in two cases it was due to the suboptimal contrast enhancement owing to poor bolus timing. In the cases of low signal/noise ratio, a smooth filter was applied to reduce the noise. The results of this study provide useful information about the reduction of the radiation dose and the medium iodine contrast. The diagnostic quality of the scan performed with a low dose of iodine and radiation overlays with the scans performed with the standard protocol. The study groups revealed a strong reduction dose in terms of DLP, and the quality of images was similar to the control group.