The Feasibility Of Double Low Dose Technology In Multi-slice Head And Neck CT Angiography Without Iterative Reconstruction

Objectives By exploring the the feasibility of double low dose technology in multislice head and neck CT angiography to realize the reduction in the amount of contrast agent on the base of reduction of radiation.Methods 110 cases were divided into conventional and double low group. The scanning parameter of conventional group is 120 k V, 350 m A, 1.0ml/kg iodinated contrast agent and the double low group is 100 k V, 300 m A, 0.7ml/kg. The image quality such as CT number and noise were measured and signal-to-noise ratio and contrast-to-noise ratio were computed in aortic arch, common carotid artery, internal carotid artery and middle cerebral artery. Independent t test and rank-sum test were used to analyze the difference of object image quality and subjective image quality between two groups. Kappa test was used to analyze the consistency of two images practitioner for the evaluation of subjective image quality score.Results 1 There was no statistically significant difference between conventional and double low group for the distribution of gender, age and body mass index(?2=0.99; t=-0.38, 0.68; P>0.05). 2 The CT number of all the arteries in head and neck were significant lower in conventional group than double low group(t=- 5.87~-2.71; P<0.05).3 The noise of all the arteries in head and neck were significant lower in conventional group than double low group(t=-3.82~-2.72; P<0.05). 4 The signal-to-noise ratio of aortic arch in conventional group and double low group were(19.97±8.17) and(20.74±8.25) respectively(t=-0.49; P>0.05); The signal-to-noise ratio of the left common carotid artery were(49.20 ± 18.18) and(49.59 ± 20.02) respectively(t=-0.10; P>0.05); The signal-to-noise ratio of the right common carotid artery were(48.66±14.10) and(51.75± 22.68) respectively(t=-0.86; P>0.05); The signal-to-noise ratio of the left internal carotid artery were(45.44±12.15) and(47.44±13.97) respectively(t=-0.80; P>0.05);The signal-to-noise ratio of the right internal carotid artery were(47.69 ± 13.63) and(48.16±16.84) respectively(t=-0.16; P>0.05); The signal-to-noise ratio of left middle cerebral artery were(36.33±9.62) and(38.22±13.33) respectively(t=-0.85; P>0.05);The signal-to-noise ratio of right middle cerebral artery were(36.62±11.05) and(37.21±11.33) respectively(t=-0.28; P>0.05). 5 The contrast-to-noise ratio of aortic arch in conventional group and double low group were(17.59 ± 7.57) and(18.85 ± 7.96) respectively(t=-0.85; P>0.05); The contrast-to-noise ratio of the left common carotid artery were(41.89 ± 16.92) and(43.22 ± 18.86) respectively(t=-0.39; P>0.05); The contrast-to-noise ratio of the right common carotid artery were(42.22±13.01) and(45.26± 21.62) respectively(t=-0.89; P>0.05); The contrast-to-noise ratio of the left internal carotid artery were(38.59±10.97) and(40.67±13.79) respectively(t=-0.87; P>0.05);The contrast-to-noise ratio of the right internal carotid artery were(40.35±12.06) and(41.19±16.13) respectively(t=-0.31; P>0.05); The contrast-to-noise ratio of left middle cerebral artery were(32.75±9.30) and(34.57±12.82) respectively(t=-0.85; P>0.05);The contrast-to-noise ratio of right middle cerebral artery were(33.00 ± 10.47) and(33.69± 11.08) respectively(t=-0.33; P>0.05). 6 There was no statistically significant difference between conventional group and double low group for the subjective image quality score(Z=-0.21; P>0.05). 7 The volume CT dose index, dose length product and effective dose of conventional group were 33.86 m Gy, 1342.03 m Gy·cm and 7.25 m Sv;the volume CT dose index, dose length product and effective dose of double low group were 18.00 m Gy ? 713.19 m Gy · cm and 3.85 m Sv; The Iodine load of conventional group and double low group were 320 mg I/kg and 224 mg I/kg.Conclusions On the base of meeting the diagnostic demand, double low dose technology in multi-slice head and neck CT angiography without iterative reconstruction is feasible.