Deep removal of trace C2H2 and CO2 from C2H4 by using customized potassium-exchange mordenite.

Adsorptive separation using porous materials is a promising approach for separating alkynes/olefins due to its energy efficiency, while the deep removal of trace amounts of C2H2 and CO2 from C2H4 is still very challenging for a commercial adsorbent. Herein, we report a low-cost inorganic metal cation-mediated mordenite (MOR) zeolite with the specific location and distribution of K+ cations acting as a goalkeeper for accurately controlling diffusion channels, as evidence of the experimental and simulation results. Deep purification of C2H4 from ternary CO2/C2H2/C2H4 mixtures was first realized on K-MOR with exceptional results, achieving a remarkable polymer-grade C2H4 productivity of 1742 L kg-1 for the CO2/C2H2/C2H4 mixture. Our approach which only involves adjusting the equilibrium ions, is both promising and cost-effective, and opens up new possibilities for the use of zeolites in the industrial light hydrocarbon adsorption and purification process.

Corrective effects of maternal extreme flexure and hip abduction combined with contralateral side-lying on persistent foetal occipito-posterior position.

AIMS: To observe the corrective effects of maternal extreme flexure and hip abduction combined with contralateral side-lying on persistent foetal occipito-posterior position. BACKGROUND: Digital rotation and other methods are used for correction of a persistent foetal occipito-posterior position. However, digital rotation readily causes damage to mother and foetus, and the correction rates of other methods are low. DESIGN: In this observational study, pregnant women were randomly divided into 2 groups according to different postures and their outcomes were compared. METHODS: A total of 238 women with persistent foetal occipito-posterior position gave birth in our hospital between January 2015 and June 2017. Of these 238 cases, 12 women declined to participate. The 226 pregnant women were divided into study group (maternal extreme flexure and hip abduction combined with contralateral side-lying, n = 114) and control group (contralateral side-lying alone, n = 112). RESULTS: The correction and spontaneous labour rates were higher in the study group than in the control group (P < .05). The duration between initial and successful correction and birth process were shorter in the study group than in the control group (P < .05). CONCLUSION: Maternal extreme flexure and hip abduction combined with contralateral side-lying has better correction effect on persistent foetal occipito-posterior position.

Detection and size measurements of pulmonary nodules in ultra-low-dose CT with iterative reconstruction compared to low dose CT.

BACKGROUND: In this study, the accuracy of ultra-low-dose computed tomography (CT) with iterative reconstruction (IR) for detection and measurement of pulmonary nodules was evaluated. METHODS: Eighty-four individuals referred for lung cancer screening (mean age: 54.5±10.8 years) underwent low-dose computed tomography (LDCT) and ultra-low-dose CT. CT examinations were performed with attenuation-based tube current modulation. Reference tube voltage and current were set to 120kV/25mÅs for LDCT and 80kV/4mÅs for ultra-low-dose CT. CT images were reconstructed with filtered back projection (FBP) for LDCT, and with FBP and IR for ultra-low-dose CT datasets. A reference standard was established by a consensus panel of 2 different radiologists on LDCT. Volume and diameter of the solid nodules were measured on LDCT with FBP and ultra-low dose CT with FBP and IR. Interobserver and interscan variability were analyzed and compared by the Bland-Altman method. RESULTS: A total of 127 nodules were identified, including 105 solid nodules, 15 part solid nodules, 7 ground glass nodules. On ultra-low-dose CT scans, the effective radiation dose was 0.13±0.11mSv. A total of 113 (88.9%) and 110 (86.6%) true-positive nodules with FBP versus 117 (92.1%) and 118(92.9%) with IR were detected by two observers, respectively. The volume and size of the 105 solid nodules were measured, with mean volume/diameter of 46.5±46.6 mm(3)/5.1±1.6mm. There was no significant difference in nodule volume or diameter measurements between ultra-low-dose CT and LDCT protocols for solid nodules. CONCLUSIONS: Ultra-low-dose CT with iterative reconstruction has high sensitivity for lung nodule detection without significant difference in nodule size and volume measurement compared to LDCT.

Assessment of pancreatic adenocarcinoma: Use of low-dose whole pancreatic CT perfusion and individualized dual-energy CT scanning.

INTRODUCTION: The objective of this study was to investigate the value of low-dose whole pancreatic computed tomography (CT) perfusion integrated with individualized dual-energy CT (DECT) scanning in the diagnosis of pancreatic adenocarcinoma. METHODS: Twenty patients with pancreatic adenocarcinoma underwent pancreatic CT perfusion as well as individualized dual-phase DECT pancreatic scans. Perfusion characteristics of non-tumourous pancreatic parenchyma and pancreatic adenocarcinoma were analysed. Weighted-average 120 kVp images and the optimal monoenergetic images in dual phase were reconstructed and the contrast noise ratio (CNR) of pancreas-to-tumour were compared. RESULTS: There were significant difference on blood flow as well as blood volume between pancreatic adenocarcinoma and the non-tumourous pancreatic parenchyma (P < 0.05), whereas no difference on permeability (P > 0.05). CNRs of pancreas-to-tumour in individualized pancreatic phase were significantly higher than those in venous phase (P < 0.05), and CNRs of optimal monoenergetic images were higher than those on weighted-average 120 kVp images (P < 0.05) in both phase. Total effective radiation dose of CT examination was around 9.32-13.75 mSv. CONCLUSIONS: Low-dose whole pancreatic CT perfusion can provide functional information, and the individualized pancreatic phase DECT scan is the optimal method for detecting pancreatic adenocarcinomas. The integration of the two techniques has great value in clinical application.

Diagnostic Value of Prospective Electrocardiogram-triggered Dual-source Computed Tomography Angiography for Infants and Children with Interrupted Aortic Arch.

BACKGROUND: Accurate assessment of intra- as well as extra-cardiac malformations and radiation dosage concerns are especially crucial to infants and children with interrupted aortic arch (IAA). The purpose of this study is to investigate the value of prospective electrocardiogram (ECG)-triggered dual-source computed tomography (DSCT) angiography with low-dosage techniques in the diagnosis of IAA. METHODS: Thirteen patients with suspected IAA underwent prospective ECG-triggered DSCT scan and transthoracic echocardiography (TTE). Surgery was performed on all the patients. A five-point scale was used to assess image quality. The diagnostic accuracy of DSCT angiography and TTE was compared with the surgical findings as the reference standard. A nonparametric Chi-square test was used for comparative analysis. P <0.05 was considered as a significant difference. The mean effective radiation dose (ED) was calculated. RESULTS: Diagnostic DSCT images were obtained for all the patients. Thirteen IAA cases with 60 separate cardiovascular anomalies were confirmed by surgical findings. The diagnostic accuracy of TTE and DSCT for total cardiovascular malformations was 93.7% and 97.9% (P > 0.05), and that for extra-cardiac vascular malformations was 92.3% and 99.0% (P < 0.05), respectively. The mean score of image quality was 3.77 ± 0.83. The mean ED was 0.30 ± 0.04 mSv (range from 0.23 mSv to 0.39 mSv). CONCLUSIONS: In infants and children with IAA, prospective ECG-triggered DSCT with low radiation exposure and high diagnostic efficiency has higher accuracy compared to TTE in detection of extra-cardiac vascular anomalies.

Ultralow-radiation-dose chest CT: accuracy for lung densitometry and emphysema detection.

OBJECTIVE: The purpose of this study was to determine whether ultralow-radiation-dose chest CT can be used for quantification of lung density and for emphysema detection in participants undergoing lung cancer screening. SUBJECTS AND METHODS: Fifty-two patients were prospectively enrolled and underwent scanning twice with low-dose CT (reference parameters, 120 kV, 50 effective mAs) and ultralow-dose CT (reference parameters, 80 kV, 4-5 effective mAs). Images were reconstructed by filtered back projection (FBP) for low-dose CT and FBP and iterative reconstruction (IR) for ultralow-dose CT. Radiation dose was recorded. Image noise, mean lung attenuation, 15th percentile of lung attenuation, and emphysema index were measured in each image series and compared. Test characteristics of ultralow-dose CT in detecting more than subtle emphysema (emphysema index≥3%) were calculated. RESULTS: The effective dose of low-dose CT was 2.1±0.5 mSv, and that of ultralow-dose CT was 0.13±0.04 mSv. Compared with the findings for low-dose CT, absolute overestimation of emphysema index was 7% on ultralow-dose CT images reconstructed with FBP and 2% on those processed with IR. The 15th percentile of lung attenuation was underestimated by 21.3 HU on ultralow-dose FBP images and by 5.8 HU on IR images. No relevant bias was observed for mean lung attenuation. Four patients (8%) had more than subtle emphysema. The emphysema index measured at ultralow-dose CT with FBP and IR had 100% and 100% sensitivity and 92% and 96% specificity in identifying patients with more than subtle emphysema at a cutoff of greater than 12.1% for FBP and greater than 6.7% for IR. CONCLUSION: Ultralow-dose chest CT performed for lung cancer screening can be used for quantification of lung density and for emphysema detection. IR improves the accuracy of ultralow-dose CT in this setting.

Can virtual non-enhanced CT be used to replace true non-enhanced CT for the detection of palpable cervical lymph nodes? A preliminary study.

PURPOSE: To investigate the potential of virtual non-contrast CT (VNCT) from dual-energy CT to replace true nonenhanced CT (TNCT) for the detection of enlarged cervical lymph nodes. MATERIALS AND METHODS: Thirty-nine patients with 94 histopathologically proven cervical lymph nodes were imaged with the dual-energy CT technique. VNCT images from the arterial [VNCT-A] and venous phases [VNCT-V] were obtained with the liver VNC application. The mean CT number and signal-to-noise ratio (SNR) were compared. Image quality was evaluated with a score scale of 1-5. Effective dose (ED) was calculated and compared. RESULTS: Mean CT numbers of cervical lymph nodes were higher on VNCT than on TNCT (P = 0.034). There was no difference in the SNR among three sets of non-enhanced CT images, but the CNR of VNCT images was higher than that of TNCT images (P < 0.001). Image quality of VNCT from two phases was comparable to that of TNCT (P = 0.070). There was no difference in image quality of three sets of non-enhanced CT images (P > 0.05). ED from dual-phase dual-energy CT was lower than that from tri-phase CT scans (P < 0.001). CONCLUSION: VNCT images from dual-energy CT of the neck had diagnostic image quality; they have the potential to replace TNCT, thus reducing the radiation dose.

Impact of sinogram affirmed iterative reconstruction (SAFIRE) algorithm on image quality with 70 kVp-tube-voltage dual-source CT angiography in children with congenital heart disease.

PURPOSE: To compare the image quality and diagnostic accuracy between sinogram affirmed iterative reconstruction (SAFIRE) algorithm and filtered back projection (FBP) reconstruction algorithm at 70 kVp-tube-voltage DSCT angiography in children with congenital heart disease (CHD). MATERIALS AND METHODS: Twenty-eight patients (mean age: 13 months; range: 2-48 months; male: 16; female: 12; mean weight: 8 kg) with CHD underwent 70 kVp DSCT angiography. Imaging data were reconstructed with both FBP and SAFIRE algorithms. Subjective image quality was evaluated on a five-point scale. The parameters of image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) on the objective image quality were compared for the two reconstruction algorithms. Surgery was performed in 20 patients, whereas conventional cardiac angiography (CCA) was performed in 8 patients. The diagnostic accuracy was evaluated on the surgical and/or CCA findings. The effective radiation doses were calculated. RESULTS: Compared to FBP algorithm, SAFIRE algorithm had significantly higher scores for subjective image quality (P<0.05), and lower image noise (P<0.05) as well as higher SNR & CNR values (P<0.05). There was no significant difference in the diagnostic accuracy between the FBP and SAFIRE algorithm (χ2 = 1.793, P>0.05). The mean effective dose for 70 kVp DSCT angiography was 0.30±0.13 mSv. CONCLUSIONS: The SAFIRE algorithm can significantly reduce image noise and improve the image quality at 70 kVp DSCT angiography for the assessment of CHD in children.

Abdominal aortic intimal flap motion characterization in acute aortic dissection: assessed with retrospective ECG-gated thoracoabdominal aorta dual-source CT angiography.

OBJECTIVES: To evaluate the feasibility of dose-modulated retrospective ECG-gated thoracoabdominal aorta CT angiography (CTA) assessing abdominal aortic intimal flap motion and investigate the motion characteristics of intimal flap in acute aortic dissection (AAD). MATERIALS AND METHODS: 49 patients who had thoracoabdominal aorta retrospective ECG-gated CTA scan were enrolled. 20 datasets were reconstructed in 5% steps between 0 and 95% of the R-R interval in each case. The aortic intimal flap motion was assessed by measuring the short axis diameters of the true lumen and false lumen 2 cm above of celiac trunk ostium in different R-R intervals. Intimal flap motion and configuration was assessed by two independent observers. RESULTS: In these 49 patients, 37 had AAD, 7 had intramural hematoma, and 5 had negative result for acute aortic disorder. 620 datasets of 31 patients who showed double lumens in abdominal aorta were enrolled in evaluating intimal flap motion. The maximum and minimum true lumen diameter were 12.2 ± 4.1 mm (range 2.6 ∼ 17.4) and 6.7 ± 4.1 mm (range 0 ∼ 15.3) respectively. The range of intimal flap motion in all patients was 5.5 ± 2.6 mm (range 1.8 ∼ 10.2). The extent of maximum true lumen diameter decreased during a cardiac cycle was 49.5% ± 23.5% (range 12% ∼ 100%). The maximum motion phase of true lumen diameter was in systolic phase (5% ∼ 40% of R-R interval). Maximum and minimum intimal flap motion was at 15% and 75% of the R-R interval respectively. Intimal flap configuration had correlation with the phase of cardiac cycle. CONCLUSIONS: Abdominal intimal flap position and configuration varied greatly during a cardiac cycle. Retrospective ECG-gated thoracoabdominal aorta CTA can reflect the actual status of the true lumen and provide more information about true lumen collapse. This information may be helpful to diagnosis and differential diagnosis of dynamic abstraction.

Low-dose whole organ CT perfusion of the pancreas: preliminary study.

OBJECTIVES: To investigate the feasibility of low-dose whole pancreas CT perfusion in the clinical practice. METHODS: Sixty-one patients suspected pancreatic disease underwent low-dose whole pancreas CT perfusion scan (by body weight, group A: 70 kV, 120 mAs; group B: 80 kV, 100 mAs) and the individualized pancreas scan. Forty-six patients were enrolled. Perfusion characteristics, such as, blood flow, blood volume and permeability, were analyzed. The effective radiation dose of the whole pancreas CT perfusion and the total CT scan protocol were recorded. CT findings were histologically confirmed by surgical intervention or diagnostic puncture. RESULTS: Of the 46 cases, 33 were pancreatic adenocarcinoma, 5 were solid-pseudo-papillary tumors of pancreas, 8 cases of pancreatic endocrine tumors on the perfusion study. There was significant interobserver agreement on the measurement of normal pancreatic CT perfusion parameters of group A (n = 28)and group B (n = 18), respectively (p > 0.05). For the normal pancreas, there was no significant difference on CT perfusion parameters between group A and group B (p > 0.05). There were significant differences on blood flow as well as blood volume between the pancreatic adenocarcinomas and the normal pancreas (p < 0.001), whereas no difference on the permeability (p > 0.05). The time to peak of the normal pancreas is 28.94 ± 4.37 s (range from 24 to 38 s). Different pancreatic tumors had different types of time attenuation curve (TAC). TACs were different between pancreatic adenocarcinomas and normal pancreas. The effective radiation dose of the whole pancreas CT perfusion of Group A and Group B were 3.60 and 4.88 mSv (DLP 246 and 325 mGy cm), respectively, and the total radiation dose was around 8.01-16.22 mSv. CONCLUSIONS: Low-dose whole pancreatic CT perfusion can effectively reduce radiation dose, and provide the best phase for the individualized pancreas scan, which has great value in the clinical practice.

Dual source CT angiography in popliteal artery entrapment syndrome.

AIM: To evaluate the clinical value of dual source computed tomography (DSCT) angiography in the diagnosis and treatment for popliteal artery entrapment syndrome (PAES). MATERIALS AND METHODS: 8 patients with PAES were retrospectively reviewed. 64-slice dual source CT angiography was performed based on the following protocol: 100 mL of Iopamidol (370 mgI/mL) was injected at a rate of 3.5 mL/s and arterial phase images were obtained by using bolus tracking. Axial DSCT images and reconstructed images including multi-planar reconstruction (MPR), maximum intensity projection (MIP), volume rendering (VR) were collected and analysed. All patients underwent Doppler colour ultrasound examinations and surgeries. RESULTS: The popliteal artery and the neighbouring muscular structures were clearly shown on the axial images revealing the cause of the arterial entrapment. Furthermore, the site and length of the segmental occlusion and collateral developments were well demonstrated on reconstructed images. Characterisation and classification based on DSCT angiography were confirmed by surgeries. PAES was accurately diagnosed by DSCT angiography in all enrolled patients. In contrary, only 5 PAES cases were accurately diagnosed by ultrasound examination. CONCLUSION: DSCT angiography is a noninvasive and valuable tool in the diagnosis of PAES and plays an important role in the determination of treatment plans.

Computed tomography coronary angiography with a consistent dose below 2 mSv using double prospectively ECG-triggered high-pitch spiral acquisition in patients with atrial fibrillation: initial experience.

To evaluate the feasibility and imaging quality of double prospectively ECG-triggered high-pitch spiral acquisition mode (double flash mode) for coronary computed tomography angiography (CTCA) in patients with atrial fibrillation (AF). 47 patients (11 women, 36 men; mean age 64.5 ± 12.1 years) were enrolled for CTCA examinations using a dual-source CT with 2 × 128 × 0.6 mm collimation, 0.28 s rotation time and a pitch of 3.4. Double flash mode was prospectively triggered first at 60 % and later at 30 % of the R-R interval within two cardiac cycles. Image quality was evaluated using a four-point scale (1 = excellent, 4 = non-assessable). From 672 coronary artery segments, 77.5 % (521/672) was rated as score of 1, 20.8 % (140/672) as score of 2, 1.2 % (8/672) as score of 3 and 0.4 % (3/672) was rated as 'non-assessable'. The average image quality score was 1.25 ± 0.38 on a per segment basis. Mean dose-length product for CTCA was 92.6 ± 28.2 mGy cm, the effective dose was 1.30 ± 0.39 mSv (0.64-1.97 mSv). In patients with AF, double prospectively ECG-triggered high-pitch spiral acquisition mode could be a feasible and valuable scan mode for CTCA with a consistent dose below 2 mSv as well as diagnostic imaging quality.

Prospectively electrocardiogram-gated high-pitch spiral acquisition mode dual-source CT coronary angiography in patients with high heart rates: comparison with retrospective electrocardiogram-gated spiral acquisition mode.

OBJECTIVE: To assess the image quality and effective radiation dose of prospectively electrocardiogram (ECG)-gated high-pitch spiral acquisition mode (flash mode) of dual-source CT (DSCT) coronary angiography (CTCA) in patients with high heart rates (HRs) as compared with retrospectively ECG-gated spiral acquisition mode. MATERIALS AND METHODS: Two hundred and sixty-eight consecutive patients (132 female, mean age: 55 ± 11 years) with mean HR > 65 beats per minute (bpm) were prospectively included in this study. The patients were divided into two groups. Collection was performed in group A CTCA using flash mode setting at 20-30% of the R-R interval, and retrospectively ECG-gated spiral acquisition mode in group B. The image noise, contrast-to-noise ratio (CNR), image quality scores, effective radiation dose and influencing factors on image quality between the two groups were assessed. RESULTS: There were no significant differences in image quality scores and proportions of non-diagnostic coronary artery segments between two groups (image quality scores: 1.064 ± 0.306 [group A] vs. 1.084 ± 0.327 [group B], p = 0.063; proportion of non-diagnostic coronary artery segments: segment-based analysis 1.52% (group A) vs. 1.74% (group B), p = 0.345; patient-based analysis 7.5% (group A) vs. 6.7% (group B), p = 0.812). The estimated radiation dose was 1.0 ± 0.16 mSv in group A and 7.1 ± 1.05 mSv in group B (p = 0.001). CONCLUSION: In conclusion, in patients with HRs > 65 bpm without cardiac arrhythmia, the prospectively high-pitch spiral-acquisition mode with image-acquired timing set at 20-30% of the R-R interval provides a similar image quality and low rate of non-diagnostic coronary segments to the retrospectively ECG-gated low-pitch spiral acquisition mode, with significant reduction of radiation exposure.

Accuracy, image quality and radiation dose comparison of high-pitch spiral and sequential acquisition on 128-slice dual-source CT angiography in children with congenital heart disease.

OBJECTIVES: To compare accuracy, image quality and radiation dose between high-pitch spiral and sequential modes on 128-slice dual-source computed tomographic (DSCT) angiography in children with congenital heart disease (CHD). METHODS: Forty patients suspected with CHD underwent 128-slice DSCT angiography with high-pitch mode and sequential mode respectively. All the anomalies were confirmed by the surgical and/or the conventional cardiac angiography (CCA) findings. The diagnostic accuracy, the subjective and objective image quality and effective radiation doses were compared. RESULTS: There was no significant difference in diagnostic accuracy (χ ( 2 ) = 0.963, P > 0.05), the objective parameters for image quality (P > 0.05) and the image quality of great vessels (u = 167.500, P > 0.05) between the two groups. The image quality of intracardiac structures and coronary arteries was significantly better in the sequential mode group than that in the high-pitch group (u = 112.500 and 100.000, P < 0.05). The mean effective dose in high-pitch group (0.17 ± 0.05 mSv) was significantly lower (t = 5.287, P < 0.05) than that in the sequential mode group (0.29 ± 0.09 mSv). CONCLUSIONS: Both the high-pitch and the sequential modes for 128-slice DSCT angiography provide high accuracy for the assessment of CHD in children, while the high-pitch mode, even with some image quality decrease, further significantly lowers the radiation dose. KEY POINTS: • Modern CT provides excellent anatomical detail of congenital heart disease. • Dual source CT systems offer high-pitch spiral and sequential modes. • The high-pitch mode provides high accuracy for the assessment of CHD. • A few images using the high-pitch mode were occasionally slightly degraded. • But the high-pitch mode significantly lowers the radiation dose.

The value of MDCT in diagnosis of hyaline-vascular Castleman's disease.

PURPOSE: Castleman's disease (CD) is an uncommon entity characterized by a massive growth of lymphoid tissue. There are two types: the hyaline-vascular (HV) type and the plasma cell (PC) type. The purpose of this study was to evaluate the clinical value of multiple detector computed tomography (MDCT) in the diagnosis and planning of treatment for hyaline-vascular CD. MATERIALS AND METHODS: Fifty-two cases of confirmed hyaline-vascular CD were retrospectively reviewed. Unenhanced and contrast-enhanced MDCT scans had been performed in all patients, followed by surgery and pathological analysis of the lesion. Original MDCT transverse and reconstructed images were used for image interpretation. Features of the lesion and its adjacent structures were identified. RESULTS: The lesion was present in the thorax of 24 patients and the abdomen in 28. Obvious features of hyaline-vascular CD (especially feeding vessels and draining veins) and its adjacent structures were demonstrated on 52 patients. CONCLUSION: On MDCT imaging, original MDCT transverse and reconstructed images provide an excellent tool for diagnosis of hyaline-vascular CD and have high value in the determination of a treatment plan.

Assessment of thoracic aortic elasticity: a preliminary study using electrocardiographically gated dual-source CT.

OBJECTIVES: To gain a new insight into the elastic properties of the thoracic aorta in patients without aortic diseases using electrocardiographically (ECG)-gated dual-source (DS) CT. METHODS: 56 subjects with no cardiovascular disease, selected from 2,700 people undergoing ECG-gated DSCT examination, were divided into three groups according to their age. CT data were reconstructed in 5% step throughout the RR interval. Diameter and area were measured at the curve of the ascending aorta (AA) and at the same level of the descending aorta (DA). The pulsation and elasticity of the aorta were evaluated. RESULTS: Aortic diameter changes were noted throughout the cardiac cycle. The maximum average diameter was seen at an RR interval of 24.02 ± 4.99% for the AA and 25.63 ± 4.77% for the DA. The minimum was at 93.5 ± 4.04% for the AA and 96.6 ± 4.58% for the DA. There was an age-dependent decrease in elasticity, while different correlation coefficients were found between various age groups and different elastic parameters. CONCLUSION: The properties of aortic pulsation and wall elasticity could be well shown by ECG-gated DSCT. The new findings regarding segment difference and age relevance were significant and should be taken into account in clinical trials and treatments for the elasticity related cardiovascular diseases.

Low-dose prospective ECG-triggering dual-source CT angiography in infants and children with complex congenital heart disease: first experience.

OBJECTIVE: To explore the clinical value of low-dose prospective ECG-triggering dual-source CT (DSCT) angiography in infants and children with complex congenital heart disease (CHD) compared with transthoracic echocardiography (TTE). METHODS: Thirty-five patients (mean age: 16 months, range: 2 months to 6 years; male 15; mean weight: 12 kg) underwent low-dose prospective ECG-triggering DSCT angiography and TTE. Surgeries were performed in 29 patients, and conventional cardiac angiography (CCA) was performed in 8 patients. The accuracy was calculated based on the surgical and/or CCA findings. The overall imaging quality was evaluated on a five-point scale. RESULTS: A total of 146 separate cardiovascular deformities were confirmed. DSCT missed three atrial septal defects and a patent ductus arteriosus. The accuracy of DSCT angiography and TTE was 97.3% (142/146) and 92.5% (135/146), respectively. Overall test parameters for DSCT angiography and TTE were similar (sensitivity, 97.3% vs 92.5%; specificity, 99.8% vs 99.8%). The average subjective image quality score was 4.3 ± 0.7. The mean effective dose was 0.38 ± 0.09 mSv. CONCLUSIONS: Prospective ECG-triggering DSCT angiography with a very low effective radiation dose allows the accurate diagnosis of anomalies in infants and children with complex CHD compared with TTE. It has great promise to become a commonly used second-line technique for complex CHD.

Myocardial bridging on dual-source computed tomography: degree of systolic compression of mural coronary artery correlating with length and depth of the myocardial bridge.

OBJECTIVE: To investigate the correlation between the degree of systolic compression of mural coronary artery (MCA) and the length and depth of myocardial bridging (MB) with dual-source computed tomography (DSCT). METHODS: The length and depth of MB were measured from diastolic phase. All datasets were reconstructed in 5% steps of R-R interval. The optimum phases were chosen where the maximal and minimal diameters were shown. The degree of systolic compression of MCA was calculated. The correlation between length and depth of MB and the degree of systolic compression of MCA were analyzed by Pearson test. RESULTS: The minimal diameters were found in 27 sites (90.0%) from 30% to 35% R-R interval, and the maximal diameters were found in 27 sites (90.0%) from 70% to 80% R-R interval. The correlation between systolic compression of MCA and length of MB was not significant (r=0.096, P=.613); however, the correlation between systolic compression of MCA and the depth of MB was significant (r=0.675, P<.01). CONCLUSION: The minimal and maximal diameters of MCA are usually demonstrated in 30-35% and 70-80% R-R reconstruction interval, respectively. The degree of systolic compression of MCA correlates well with the depth of MB.

Effect of nonlinear three-dimensional optimized reconstruction algorithm filter on image quality and radiation dose: validation on phantoms.

A new technique called the nonlinear three-dimensional optimized reconstruction algorithm filter (3D ORA filter) is currently used to improve CT image quality and reduce radiation dose. This technical note describes the comparison of image noise, slice sensitivity profile (SSP), contrast-to-noise ratio, and modulation transfer function (MTF) on phantom images processed with and without the 3D ORA filter, and the effect of the 3D ORA filter on CT images at a reduced dose. For CT head scans the noise reduction was up to 54% with typical bone reconstruction algorithms (H70) and a 0.6 mm slice thickness; for liver CT scans the noise reduction was up to 30% with typical high-resolution reconstruction algorithms (B70) and a 0.6 mm slice thickness. MTF and SSP did not change significantly with the application of 3D ORA filtering (P > 0.05), whereas noise was reduced (P < 0.05). The low contrast detectability and MTF of images obtained at a reduced dose and filtered by the 3D ORA were equivalent to those of standard dose CT images; there was no significant difference in image noise of scans taken at a reduced dose, filtered using 3D ORA and standard dose CT (P > 0.05). The 3D ORA filter shows good potential for reducing image noise without affecting image quality attributes such as sharpness. By applying this approach, the same image quality can be achieved whilst gaining a marked dose reduction.

Dose performance and image quality: dual source CT versus single source CT in cardiac CT angiography.

OBJECTIVE: To evaluate dose performance and image quality of 64-slice dual source CT (DSCT) in comparison to 64-slice single source CT (SSCT) in cardiac CT angiography (CTA). METHODS: 100 patients examined by DSCT and 60 patients scanned by SSCT were included in this study. Objective indices such as image noise, contrast-to-noise ratio and signal-to-noise ratio were analyzed. Subjective image quality was assessed by two cardiovascular radiologists in consensus using a four-point scale (1=excellent to 4=not acceptable). Estimation of effective dose was performed on the basis of dose length product (DLP). RESULTS: At low heart rates (<70 bpm), image quality of SSCT was equivalent to that of DSCT (P>0.05), but, at high heart rates (>70 bpm), DSCT provided robust image quality (P<0.05). The average effective dose of SSCT was 9.3+/-0.9 mSv at low heart rates (<70 bpm) while, the average estimated effective doses of DSCT were 9.1+/-1.3 mSv, 8.3+/-1.1 mSv, 7.9+/-1.1 mSv, 6.9+/-0.7 mSv, and 5.9+/-1.3 mSv, corresponding to heart rates of 50-59 bpm, 60-69 bpm, 70-79 bpm, 80-89 bpm, and 90-100 bpm. CONCLUSION: For cardiac CTA, both DSCT and SSCT can get good image quality at low heart rates (<70 bpm) with a similar radiation dose, but, at high heart rates (>70 bpm), DSCT is able to provide robust diagnostic image quality at doses far below that of SSCT.