ABSTRACT
Objective To investigate the impact of prescribed adaptive statistical iterative reconstruction V (Pre-ASiR-V) on imaging quality and radiation dosage of pure ground glass nodules (pGGN) in chest phantom,in order to obtain the optimal level of Pre-ASiR-V.Methods CT scanning for a chest phantom containing 4 artificial pGGNs was performed with Revolution CT,and the Pre-ASiR-V level was set as 0,20％,40％,60％,80％ and 100％ group,respectively.The mean noise,effective dose (ED) and the subjective scores of pGGN imaging were recorded and compared.Results The mean noise of groups (Pre-ASiR-V 0,20％,40％,60％,80％ and 100％) was (17.93±2.20)HU,(17.30±3.68)HU,(18.20± 3.44)HU,(18.80±0.20)HU,(19.87±2.56)HU and (15.90±4.56)HU,respectively (F=0.568,P=0.723).ED of these groups was 7.40 mSv,5.16 mSv,3.36 mSv,1.97 mSv,0.97 mSv and 0.33 mSv,respectively.Compared with imaging of PreASiR-V 0,the reduction percentage of ED was 30.27％,54.59％,73.38％,86.89％ and 95.54％,respectively.The subjective score of the image quality evaluated by the 2 observers had high agreement (Kappa=0.778,P=0.003),and all the scores were greater than 3.The subjective score of Pre-ASiR-V 80％ and 100％ group was slightly lower than those in other groups.Conclusion Different Pre-ASiR-V level slightly impacts the noise of high-resolution CT images of chest phantom,while reduces radiation dosage significantly.Pre-ASiR-V level of 60％ is the optimal protocol.
ABSTRACT
Objective To discuss the value of 256 spiral CT dynamic volume scanning in the diagnosis of moyamoya disease.Methods Twenty-three patients with moyamoya disease undergoing 256 spiral CT dynamic volume scanning (moyamoya group) were selected,and 18 patients having cerebrovascular disease symptoms,but the brain artery without stenosis (control group) were also selected.The volume reconstruction (VR),maximum intensity projection (MIP) and cerebral CT perfusion imaging was displayed.The cerebral CT perfusion imaging parameters of anterior,middle,posterior cerebral artery were measured and analyzed.Results VR,MIP could well reproduce lesion location,degree of stenosis and skull base abnormal vascular network change.Compared with control group,the cerebral blood volume (CBV) was increased [(8.46 ±0.91) ml/100 g vs.(2.92 ±0.72) ml/100 g],time to peak (TTP) was increased [(30.27 ±5.02) s vs.(24.83 ±4.07) s] in anterior cerebral artery,and there was significant difference (P ＜ 0.01),but there was no significant difference in the cerebral blood flow (CBF),the mean transit time (MTT)(P ＞ 0.05).Compared with control group,CBV was increased [(8.06 ± 1.05) ml/100 g vs.(6.08 ± 0.56) ml/100 g],MTT,TTP was increased [(6.34 ± 1.01) s vs.(3.83 ± 0.83) s,(32.06 ± 2.55) s vs.(25.83 ± 2.34) s] in middle cerebral artery,and there was significant difference (P＜ 0.01),but there was no significant difference in CBF (P ＞ 0.05).Compared with control group,there was no significant difference in the cerebral CT perfusion imaging parameters of posterior cerebral artery (P ＞0.05).Conclusion 256 spiral CT dynamic volume scanning can be combined with morphology and function imagings,and has important guiding significance for diagnosis of moyamoya disease.