ABSTRACT
Objective To explore the application value of pulmonary artery monitoring program for intracranial and cervical artery angiography with dual-energy CT.Methods Sixty patients performed intracranial and cervical artery angiography with dual-energy CT were divided into two groups according to the random number table.Group A (optimization group,30 patients):the monitoring points were located in the main pulmonary artery,with threshold 150 HU,trigger delay time 8-9 s,pitch 0.9,and the iohexol (350 mg I/ml) 60-65 ml.Group B (conventional group,30 patients):the monitoring points were located in aortic arch,with threshold 100 HU,trigger delay time 5 s,and the iohexol (350 mg I/ml)60-70 ml.Patients with the body weight less than 75 kg were injected with the flow rate of 4.0 ml/s,and those weight greater than 75 kg or with body mass index (BMI) greater than 27 kg/m2 were 4.5 ml/s,following 40 ml saline solution with the same flow rate respectively.All images were transferred to Siemens Syngo workstation for further processing and analysis.The attenuation values were measured on axial images in the common carotid artery,internal and external carotid artery,vertebral and basilar artery,the horizontal segment of the middle cerebral artery,the subclavian vein of injection side,the proximal,middle and distal segment of jugular vein,the straight sinus and the superior sagittal sinus.Two experienced observers blinded independently evaluated the image quality of CTA,the impact of contrast material residues artifacts of subclavian vein of injected side and the affect of venous return factors on arterial image display.Images of volume rendering technique(VR),the maximum intensity projection (MIP),and curved planar reformation (CPR) were reconstructed using dual energy bone removal and Inspace and 3D software.The mean intraluminal attenuation of contrast material (HU),the volume of contrast material and the mean image quality scores were compared with t test between the two groups.Chi-square test was used to compare of image contrast agents residual artifacts,the absence segments of the root of the neck artery,and the degree of the jugular vein return in two groups.Results The mean CT values were 372-414 HU for each segment of artery showing no significant differences between two groups (P ＞ 0.05).In group A,the CT values of the jugular vein in proximal,middle,distal segment of the two sides were (95 ± 36),(95 ± 36),(131 ±58),(133 ± 57),(174 ± 68),and (180 ± 66) HU respectively.In group B,CT values were (135 ± 58),(137 ±59),(170 ±58),(181 ±58),(218 ±62),and (224 ±68) HU.The CT value of jugular venous in group A was significantly lower than that in group B (t =-3.30--2.54,P ＜ 0.05).Case numbers of contrast agent residual artifacts of injection side subclavian vein and the absence segments of root of the neck artery at the beginning in group A (5,11) were less than that in group B (12,24) (x2 =4.02,5.65,P ＜0.05).The degree of the jugular vein return in group A were lesser severely than that in group B (x2 =6.79,6.37,P ＜0.05).Below the level of carotid artery bifurcation:slight 5 patients,severe 1 patient in group A vs.slight 15 patients,severe 9 patients in group B.Above the level of carotid artery bifurcation:slight 9 patients,severe 6 patients in group A vs.slight 12 patients,severe 17 patients in group B.Image quality scores of group A (3.84 ± 0.40) was higher than that of group B (3.64 ± 0.63) (t =4.26,P ＜0.05).Conclusions Pulmonary Artery Monitoring combines with 60-65 ml contrast material optimization scheme for intracranial and cervical artery angiography with dual energy CT can significantly reduce the degree of jugular venous return and contrast material residues artifacts of subclavian vein of injected side.This technique is helpful to improve the work efficiency and image quality.
ABSTRACT
Objective To evaluate the imaging quality and radiation doses of dual-source computed tomography (DSCT) coronary angiography at a low tube voltage in patients with medium and low heart rate.Methods Eighty-five patients[heart rate (HR) ＜ 91 beats per minute (bpm); body mass index (BMI) 17. 51-30. 00 kg/m2]suspected of coronary artery disease received retrospectively ECG-gating coronary angiography with dual-source CT scanner (Somatom Definition, Siemens) at a tube voltage of 100 kVp. For all patients, no beta-blocker was used before CT scan. According to the HR, the patients were divided into three groups: Group A, HR ≤ 59 bpm, n = 27; Group B, HR 60-69 bpm, n = 29; Group C,HR ≥70 bpm, n = 29. All images were transferred to a workstation for postprocessing. The best R-R interval reconstruction images of all groups were evaluated. The value of pitch, CT volume dosage index (CTDIvol), dose length product (DLP)and effective dose (ED)were recorded. The pitch, the score of imaging quality of coronary artery segments and the radiation dose were compared with one-way ANOVA. The influence of HR on image quality and radiation doses of coronary artery was analyzed. Results The value of pitch in Group A, Group B and Group C was 0. 241 ± 0. 025, 0. 286 ± 0. 034 and 0. 335 ± 0. 036,respectively. The mean score of imaging quality of coronary artery segments in Group A, Group B and Group C was 4. 78 ± 0. 26, 4. 66 ± 0. 56 and 4. 70 ± 0. 46, respectively. The value of CTDIvol in Group A,Group B and Group C was (18.06 ±5. 16), (19. 62 ±7. 15) and (17. 50 ±7. 13) mGy, respectively. The value of ED in group A, Group B and Group C was (4.23 ± 1.76), (4.59 ± 1.75) and (4.12 ±1.39) mSv, respectively. There was statistical difference in value of pitch among the three groups (F =60. 00, P= 0. 00). There were no statistical difference in score of imaging quality, CTDIvol and value of ED among the three groups (F = 0. 53, P = 0. 59; F = 0. 83, P = 0. 44 ; F = 0. 86, P = 0. 43). Conclusion Medium and low HR have little influences on image quality of dual-source CT coronary angiography at a low tube voltage. When the auto ECG-gating is selected, there is little influence on radiation dosage as well.