ABSTRACT
Objective To investigate the Adamkiewicz artery visualization using gemstone spectral CT angiography (CTA) with optimal monochromatic technique.Methods The prospective study was approved by the local institutional review board,and written informed consents were obtained for all the examinations.The successive 58 patients with suspected aortic aneurysm or dissection underwent aortic gemstone spectral CTA.They were divided into two groups based on the different reconstruction protocols:A,optimal monochromatic reconstruction;B,polychromatic reconstruction.Visualization rate of Adamkiewicz artery in two groups were recorded.Objective(measure CT value of the descending aorta and calculate signal-to-noise ratio [CNR]) and subjective (score of Adamkiewicz artery visualization) were evaluated.Paired samples t,Chi-square and Mann-Whitney U test were used for statistical analysis.Results CT value of descending aorta and CNR of group A [(568.4 ± 57.5)HU and (52.3 ± 8.1)] were significantly higher than group B[(346.2 ± 48.6)HU and (26.7 ± 3.7)] (t=12.70 and 15.20,P＜0.01).The visualization rate of Adamkiewicz artery in group A (94.8％,55/58) was higher than B (82.8％,48/58;x2=4.20,P=0.04).The score of group A (55 cases,3.9±0.8) was significantly higher than the group B (48 cases,3.4±1.0)(Z=-2.40,P=0.02).Conelusion Gemstone spectral CTA with optimal monochromatic reconstruction can improve the visualization efficiency and quality of the Adamkiewicz artery compared with routine polychromatic reconstruction protocol.
ABSTRACT
Purpose To implement lower artery angiography in patients with peripheral arterial occlusive disease, and to investigate the feasibility of lower extremity gemstone spectral CT angiography in improving image quality.Materials and Methods Forty-eight patients suspected with lower extremity arterial occlusive diseases were randomly divided into research group and control group. Research group (24 cases) were carried out gemstone spectral CT angiography (CTA) scan and control group (24 cases) were scanned with multi-slice spiral CT (CTA). The CT value of the common iliac artery, popliteal artery and its branches was measured and contrast to noise ratio (CNR) were calculated in both groups. The images were evaluated independently by 2 senior physicians based on a 5-level evaluation standard.Results The CT value of common iliac artery, popliteal artery, anterior tibial artery and the CNR in research group were all higher than those in control group (t=8.7, 7.9, 12.6 and 17.2,P<0.01), but the background noise was lower than that in control group (t=1.5,P<0.01). The scores of two image quality accessed by physician 1 and 2 were 110:90 and 111:93 respectively with statistical difference (Z=-7.6 and-8.0, P<0.01).Conclusion The image obtained by gemstone spectral CT optimal single energy image technique is much better than that by conventional multi-slice spiral CT in lower extremity angiography.
ABSTRACT
Objective To evaluate the differences in image quality and radiation dose in the neck CTA between low tube voltage scanning method combined with exact calculation of contrast dosage and conventional scanning methods.Methods Ninety patients who had undergone neck CTA examination from October 2012 to June 2013 were prospectively selected to perform study.Patients were randomly divided into Group A,B and C,each with 30 cases.Tube voltage and contrast amount were,respectively,120 kV and 70-80 ml for Group A (conventional group),100 kV and exact calculation for Group B,80 kV and exact calculation for Group C.Using ANOVA test,radiation dose,contrast amount,CNR were statistically analyzed among three groups.Subjective evaluations were made of image quality by two experienced radiologists based on a 5-point system.Results The effective doses in Group B and C were (4.5 ± 0.7) mSv and (2.1 ± 0.4) mSv,respectively,significantly lower than (6.6 ± 0.9) mSv in Group A,with statistically significant difference(F =72.4,P ＜ 0.05).The amounts of contrast were significantly lower in Group B and C than that in Group A,which respectively were (73.2 ± 8.2) ml for Group A and (48.2 ± 5.1) for Group B and (48.6 ± 5.4) ml for Group C,with statistically significant difference (F =56.8,P ＜ 0.05).CNRs increased respectively by 42.2％ in Group B and by 42.2％ in Group C compared with Group A,with statistically significant difference (F =72.6,P ＜ 0.05).Venous artifact images were found in 10 patients of Group A,having different effects on image quality,whereas in Group B and C,there were not vein artifacts to found.Conclusions The low tube voltage (80 kV) scanning method combined with exact calculation of contrast features not only significantly lower radiation dose and lower contrast amount used,but also improved image quality in comparison with conventional method.
ABSTRACT
Objective To probe the feasibility of gemstone spectral CT in imaging pulmonary angiography with low dose contrast medium.Methods A prospective study with multi-slice spiral CT pulmonary angiography was performed in consecutive 48 patients suspected with pulmonary embolism.Two groups (n=24 respectively)were divided at random including Group A used Gemstone spectral CT with 35 mL of contrast medium and Group B using 64-slice CT with conventional 80~90 mL of contrast medium.The CT values of the pulmonary trunk,lobe artery,pulmonary vein and ascending aorta were measured.The contrast to noise ratio of the pulmonary artery was also calculated.In addition,the image quality of CTA was evaluated independently by two experienced ra-diologists.Results The CT values of the pulmonary trunk and the subsegmental branches,and the CNR in Group A were signifi-cantly higher than those in group B,exhibiting statistical differences (t=8.6,P <0.001;t=12.2,P <0.001;t=1 1.3,P <0.001 respectively).However,the CT value of aorta in Group A was significantly lower than that in Group B (t=-7.6,P <0.001).The evaluation results of the CTA images by two radiologists showed that the image quality in Group A was better than that in Group B (Z =-8.6,P <0.001;Z =-9.0,P <0.001 ).Conclusion The image quality of pulmonary angiography with gemstone spectral CT using low contrast medium dose can be improved compared with the conventional spiral CT.
ABSTRACT
Objective To evaluate the feasibility of a low-dose contrast medium protocol for 64-slice CT angiography (CTA) of head using a low-tube-voltage setting.Methods ① Phantom study:64-slice spiral CT respectively sets 80,100,120,140 kV and 100,200,300,400,500 and 600 mA as scanning parameter lines.Analysis of the best Signal-to-noise ratios (SNR) and contrast to noise ratios (CNR).②Clinical study:to prospectively continuous select sixty-six patients with suspected intracranial aneurysm and arteriovenous malformation and so on from April to October of 2012 to perform hand CTA inspection.The random number table method for A,B two groups,33 patients in each group.Group A (conventional group)scanning parameters:120 kV,400 mA and amount of contrast agent:1 ml/kg; Group B(test group) scanning parameters:80 kV,600 mA,amount of contrast agent 0.5 ml/kg.Using independent samples t test for each group radiation dose,SNR,CNR were statistically analyzed.By two experienced radiologists to 5 points on two groups of image quality subjective evaluation.Mann-Whitney U test was used for statistical analysis of subjective evaluation.Results Group A and B group CTDIvol respectively is 59.1,27.5 mGy.Group B than in group A,CTDIvol decreased by 53.5％.A,B groups of the SNR,CNR were 71.5 ± 10.7,92.0 ± 7.4; 58.5 ± 10.5,79.6 ± 7.7,Group B than in group A SNR,CNR were enhanced by 22.3％,26.4％,differences were statistics significance (t =584.0,388.6,P ＜ 0.01).The subjective image evaluation of group B was bigher than group A (Z =31.2,23.4,P ＜ 0.05),differences were statistics significance.Two physicians on CTA images to assess the consistency of uniform height(Kappa =0.904,P ＜0.05).Conclusion In the head CTA examination,use of low tube voltage combined with low contrast dose not only can improve the image quality but also radiation dose were significantly lower.
ABSTRACT
Objective To investigate the radiation dose differences of DTS,DR and CT in diagnostic imaging of the skeletal system and analyze the sensitivity and specificity of each modality in skeletal disease diagnosis.Methods 100 relevant patients with skeletal diseases were randomly selected,who were performed with DR,DTS and CT from Feb 2010 to Mar 2012.They were divided into three groups,respectively as the DR group,the DTS group and the CT group.The complete information including DR,DTS,CT data and the final clinical diagnosis were collected and the statistical analysis after comparing radiation dose of DR,DTS and CT examination.Two experienced experts evaluated the image of three examinations and made judgments.ROC curves of reader A and B were made by using the final clinical diagnosis as gold standard.Results The average absorbed dose and effective dose of DR,DTS,CT group were [(1.9±1.8)mGy,(0.03±0.03) mSv)],[(3.5±1.5)mGy,(0.05±0.02) mSv)],[(397.7 ± 106.0) mGy· cm、(5.60 ± 1.50) mSy] respectively.The difference among the three groups was analyzed by one-way ANOVA test(F =1377,P ＜ 0.05) and had statistically significant(P ＜ 0.05).ROC curve was drawn through analyzing lesion detection credibility of three groups.The Az values of reader A and B was (0.870 ± 0.035,0.966 ± 0.018,0.974 ± 0.015) and (0.852 ± 0.038,0.951 ± 0.021,0.959 ±0.019)respectively.Do the Z-test to these examinations' area under ROC curve of lesion detection credibility.Between DR and DTS or DR and CT,there was statistically significant(P ＜ 0.05).While for CT and DTS,there was not statistically significant.The two readers' sensitivity and specificity in diagnosing skeletal lesion with DR,DTS and CT were investigated using the x2 test:CT and DTS were no statistical significance,CT and DR were statistically significant (x2 =4.833,P ＜ 0.05).Conclusions Radiation dose of DTS only accounts for about 1％ of CT examination.While its sensitivity and specificity can meet the requirements for clinical diagnosis as CT.If the DR diagnosis is unclear or suspected,DTS should be the first recommended modality used for skeletal diagnosis with lower radiation dose.