Low-concentration Contrast Research Articles

The applying of a low tube voltage combined with low dose of iodixanol to renal artery CT imaging in elderly patients

Objective To explore the clinical application of 80 kVp tube voltage combined with low dose and low concentration contrast agent in CT imaging of renal artery (CTA) in elderly patients. Methods 160 elderly patients undergoing CT angiography of renal artery or abdominal aorta in our hospital from August 2016 to June 2017 were randomized to control group (routine-dose CT with 120 kVp at 120 mAs, contrast agent of 70 ml, n=40) and double low group (X-ray tube voltage at 80 kVp and contrast agent of 50 ml), which was re-divided to double low-150 mAs group, double low-180 mAs group, and double low-210 mAs group (n=40, each). The CT value of bilateral renal arteries, their branches, and abdominal aorta at the same height of renal artery, signal to noise ratio (SNR), contrast to noise ratio (CNR), the effective radiation dose, and the incidence of adverse reaction were measured after sinogram-affirmed iterative reconstruction (SAFIRE). And the image quality was evaluated and rated on a scale from 1 to 5 by two independent qualified radiologists. Results The vascular enhancement was significantly higher in the three double low groups than in the control group (all P 0.05), while statistical differences were found in SNR and CNR in the control group versus double low-150 mAs and double low-180 mAs groups (all P<0.05). As compared with the control group, effective radiation dose was decreased in the three double low groups by 63.3% (150 mAs), 56.2% (180 mAs), 48.8% (210 mAs), respectively. All image scores in four groups were over 3 points.Mild adverse effects were observed in four cases from the control group, and no adverse effect occurred in the other three groups. Conclusions 80 kVp tube voltage combined with low dose and low concentration contrast agent can appropriately increase tube current. Combined with SAFIRE, it can not only help maintain image quality, but also decrease the damage of organs by reducing the doses of radiation and contrast agent. Key words: Tomography, computed; Contrast media; Renal artery

The combination of a reduction in contrast agent dose with low tube voltage and an adaptive statistical iterative reconstruction algorithm in CT enterography: Effects on image quality and radiation dose.

To investigate the subjective and quantitative image quality and radiation exposure of CT enterography (CTE) examination performed at low tube voltage and low concentration of contrast agent with adaptive statistical iterative reconstruction (ASIR) algorithm, compared with conventional CTE.One hundred thirty-seven patients with suspected or proved gastrointestinal diseases underwent contrast enhanced CTE in a multidetector computed tomography (MDCT) scanner. All cases were assigned to 2 groups. Group A (n = 79) underwent CT with low tube voltage based on patient body mass index (BMI) (BMI < 23 kg/m2, 80 kVp; BMI ≥ 23 kg/m2, 100 kVp) and low concentration of contrast agent (270 mg I/mL), the images were reconstructed with standard filtered back projection (FBP) algorithm and 50% ASIR algorithm. Group B (n = 58) underwent conventional CTE with 120 kVp and 350 mg I/mL contrast agent, the images were reconstructed with FBP algorithm. The computed tomography dose index volume (CTDIvol), dose length product (DLP), effective dose (ED), and total iodine dosage were calculated and compared. The CT values, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) of the normal bowel wall, gastrointestinal lesions, and mesenteric vessels were assessed and compared. The subjective image quality was assessed independently and blindly by 2 radiologists using a 5-point Likert scale.The differences of values for CTDIvol (8.64 ± 2.72 vs 11.55 ± 3.95, P < .001), ED (6.34 ± 2.24 vs 8.52 ± 3.02, P < .001), and DLP (422.6 ± 149.40 vs 568.30 ± 213.90, P < .001) were significant between group A and group B, with a reduction of 25.2%, 25.7%, and 25.7% in group A, respectively. The total iodine dosage in group A was reduced by 26.1%. The subjective image quality did not differ between the 2 groups (P > .05) and all image quality scores were greater than or equal to 3 (moderate). Fifty percent ASIR-A group images provided lower image noise, but similar or higher quantitative image quality in comparison with FBP-B group images.Compared with the conventional protocol, CTE performed at low tube voltage, low concentration of contrast agent with 50% ASIR algorithm produce a diagnostically acceptable image quality with a mean ED of 6.34 mSv and a total iodine dose reduction of 26.1%.

The feasibility of low-concentration contrast and low tube voltage in computed tomography perfusion imaging: an animal study.

Aim: To investigate the feasibility of low-concentration contrast (270 mg/ml) together with low tube voltage (80 kV) and adaptive iterative dose reduction (AIDR)-3D reconstruction in liver computed tomography (CT) perfusion imaging.Method: A total of 15 healthy New Zealand rabbits received two CT scans each. The first scan (control) was acquired at 100 kV and 100 mA with iopromide (370 mg/ml), while the second scan (experimental) was acquired at 80 kV and 100 mA with iodixanol (270 mg/ml) 24 h after the first scan. The obtained images were reconstructed with filtered back projection (FBP) and AIDR-3D in the control and experimental groups respectively. The perfusion parameters (hepatic artery perfusion [HAP], portal vein perfusion [PVP], hepatic perfusion index [HPI], and total liver perfusion [TLP]) and image quality (image quality score, average CT value of abdomen aorta, signal-to-noise ratio [SNR], contrast-to-noise ratio [CNR], and figure of merit [FOM]) were compared using a paired t-test or Mann–Whitney U test between the two groups, when appropriate. The effective radiation dose and iodine intake were also recorded and compared.Results: With the exception of the FOM criteria, the image quality and perfusion parameters were not significantly different between the two groups. The effective radiation dose and iodine intake were 38.79% and 27.03% lower respectively, in the experimental group.Conclusion: Low-concentration contrast (iodixanol, 270 mg/ml) together with low tube voltage (80 kV) and AIDR-3D reconstruction help to reduce radiation dose and iodine intake without compromising perfusion parameters and image quality in liver CT perfusion imaging.

Application of Dual-Energy CT Non-Linear Fusion Technology in Improving CTA Image Quality of Renal Cancer

Objective: To explore the significance of dual-energy CT non-linear fusion technique in improving the quality of CTA image of renal cancer. Methods: The CTA images of 100 patients who had been confirmed by pathology as renal cancer were collected and were randomly divided into experimental group and control group with 50 cases respectively. The two groups of patients were treated with iodine concentration of 300 mg/ml and 350 mg/ml non-ionic contrast agent, with a dosage of 1.5 ml/kg and an injection rate of 4 ml/s. The contrast agent intelligently tracking method was adopted bolus. The control group used the conventional CTA scanning, with a reference tube voltage/tube current of 100 kv/ref150 mas. The experimental group adopted the double energy scanning, with ball tube A and ball tube B. The reference tube voltage/tube current was 100 kv/ref250 mas and sn150 kv/ref125 mas respectively. The images of the experimental group were non-linear fused to obtain the Mono+ 55 kev single-energy images. The CT value, SNR contrast ratio of the abdominal aorta, renal artery and tumor tissue of the experimental group images and the 100 KV images and the Mono+ 55 kev images of the control group were compared. The objective evaluation and subjective evaluation of the image quality of the three groups of images was performed. Results: The results showed that the 100 kV images of the experimental group were statistically different from those of the control group (P05) in CT value, SNR and CNR (P 0.05). The subjective evaluation of image quality showed that there was no significant difference between Mono+ 55 kev images and control group images, and the quality of Mono+ 55 kev images was higher than that of experimental group 100 kV images. Conclusion: The dual-energy CT non-linear fusion technique can improve the quality of CTA image in patients with renal cancer, and it is possible to obtain high quality CTA images with low iodine concentration contrast agent.

Low kV and Low Concentration Contrast Agent with Iterative Reconstruction of Computed Tomography (CT) Coronary Angiography: A Preliminary Study.

BackgroundThe aim of this study was to evaluate the image quality and radiation dose of CT coronary angiography (CTCA) with low kV, low concentration contrast agent, and iterative reconstruction.Material/MethodsNinety cases were randomly divided into 3 groups according to contrast agent concentration: group A 270 mg/ml (100 kV), group B 350 mg/ml (120 kV), and group C 370 mg/ml (120 kV), with 30 cases per group. Tube current was 200–250 mAs. Collimator width was 128×0.6 mm. Rotation speed was 0.27 s. The CT value of the left and right coronary arteries and the ascending aortic root was measured. The SNR and CNR of the images were calculated to evaluate the image quality objectively. The CTDI, DLP, and contrast injection were recorded.ResultsThere were no significant differences in sex, age, weight, height, and BMI among the 3 groups. There was no statistically significant difference between left and right coronary artery and ascending aortic root CT value, background noise, SNR, and CNR. Compared to B and C, the ED in group A decreased by about 27.58% and 28.21%, respectively. The total amount of iodine in group A was decreased by about 21.27% and 24.83%, respectively compared with groups B and C.ConclusionsLow kV and low concentration contrast agent combined with iterative reconstruction for CTCA imaging produced image quality consistent with that of conventional CTCA and significantly reduced the dosage of the radiation and injected iodine.

Ultra-low-dose CT coronary angiography using 128-slice dual source CT with low concentration contrast agent: initial experience.

To optimize and evaluate an ultra-low-dose (ULD) technique for CT coronary angiography (CTCA). Eighty-two patients were randomly divided into two groups. ULD and routine CTCA were performed in groups A and B. Image quality, radiation dose and contrast agent were evaluated. The effective dose (ED) was 0.20±0.01mSv for the ULD technique, a decrease of 87% (t=-21.182, P<0.001) compared with the control group. The total iodine content was 8.10±0g, a decrease of 62% (t=-73.458, P<0.001) compared with 21.10±1.15g for the control group. The assessment rates for both groups were the same (99.26 vs 99.64%, χ 2 =0.727, P=0.394). The contrast-to-noise ratio was 19.31±7.95 for group A and 20.73±5.07 for group B: the difference was not statistically significant (t=-1.678, P=0.095). Using an ultra-low radiation dose and contrast agent technique, while maintaining an assessable image and improving the safety of the medical examination, was a feasible and reliable method for CTCA.

Low-Dose Scanning Technology Combined with Low-Concentration Contrast Material in Renal Computed Tomography Angiography (CTA): A Preliminary Study.

BackgroundThis study is to investigate the feasibility of low iodine concentration contrast material (CM) combined with low tube voltage and adaptive statistical iterative reconstruction (ASIR) in renal computed tomography angiography (CTA).Material/MethodsA total of 136 patients were enrolled in this prospective trial, and randomly divided into two groups: group A (n=68) and group B (n=68). Group A received 120-kVp and iopromide (370 mg/mL) with filtered back projection (FBP) reconstruction, and group B received 100-kVp and iodixanol (270 mg/mL) with ASIR 40% (ASIR40). An equal iodine dose (300 mg/kg body weight) and the same iodine delivery rate (1,500 mg I/s) were given to all patients. Density, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured, and the image quality and visualization of renal arteries were scored. Dose-length product (DLP) and CT dose index volume (CTDIvol) were recorded, and effective doses (ED) were calculated.ResultsThere was no significant difference in image noise between groups A and B (p>0.05). The vessel attenuation, SNR, and CNR were significantly higher in group B than group A (all p<0.05). The subjective image quality and visualization of renal artery branches were similar in these two groups (p>0.05). Compared with group A, the CTDIvol, DLP, and ED in group B were decreased by 38.58%, 37.24%, and 37.24%, respectively (p=0.000).ConclusionsCompared with 120-kVp with FBP reconstruction, the protocol of 100-kVp with ASIRP40 reconstruction provided high-quality renal CTA results, which allowed for reduced iodine concentration and decreased radiation dose.

Evaluation of a High Concentrated Contrast Media Injection Protocol in Combination with Low Tube Current for Dose Reduction in Coronary Computed Tomography Angiography: A Randomized, Two-center Prospective Study

The study aimed to prospectively evaluate the radiation dose reduction potential and image quality (IQ) of a high-concentration contrast media (HCCM) injection protocol in combination with a low tube current (mAs) in coronary computed tomography angiography. Eighty-one consecutive patients (mean age: 62 years; 34 females; body mass index: 18-31) were included and randomized-assigned into two groups. All computed tomography (CT) examinations were performed in two groups with the same tube voltage (100 kV), flow rate of contrast medium (5.0 mL/s), and iodine dose (22.8 g). An automatic mAs and low concentration contrast medium (300 mgI/mL) were used in group A, whereas effective mAs was reduced by a factor 0.6 along with HCCM (400 mgI/mL) in group B. Radiation dose was assessed (CT dose index [CTDIvol] and dose length product), and vessel-based objective IQ for various regions of interest (enhancement, noise, signal-to-noise ratio, and contrast-to-noise ratio), subjective IQ, noise, and motion artifacts were analyzed overall and vessel-based with a 5-point Likert scale. The CT attenuation of coronary arteries and image noise in group B were significantly higher than those in group A (ranges: 507.5-548.1 Hounsfield units vs 407.5-444.5 Hounsfield units; and 20.3 ± 8.6 vs 17.7 ± 8.0) (P ≤ 0.0166). There was no significant difference between the two groups in signal-to-noise ratio, contrast-to-noise ratio, and subjective IQ of coronary arteries (29.4-31.7, 30.0-37.0, and medium score of 5 in group A vs 29.4-32.4, 27.7-36.3, and medium score of 5 in group B, respectively, P ≥ 0.1859). Both mean CTDIvol and dose length product in group B were 58% of those of group A. HCCM combined with low tube current allows dose reduction in coronary computed tomography angiography and does not compromise IQ.

Feasibility of dual-low scheme combined with iterative reconstruction technique in acute cerebral infarction volume CT whole brain perfusion imaging.

The feasibility of application of low-concentration contrast agent and low tube voltage combined with iterative reconstruction in whole brain computed tomography perfusion (CTP) imaging of patients with acute cerebral infarction was investigated. Fifty-nine patients who underwent whole brain CTP examination and diagnosed with acute cerebral infarction from September 2014 to March 2016 were selected. Patients were randomly divided into groups A and B. There were 28 cases in group A [tube voltage, 100 kV; contrast agent, iohexol (350 mg I/ml), reconstructed by filtered back projection] and 31 cases in group B [tube voltage, 80 kV; contrast agent, iodixanol (270 mg I/ml), reconstructed by algebraic reconstruction technique]. The artery CT value, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), dose length product, effective dose (ED) of radiation and brain iodine intake of both groups were measured and statistically analyzed. Two physicians carried out kappa (κ) analysis on the consistency of image quality evaluation. The difference in subjective image quality evaluation between the groups was tested by χ2. The differences in CT value, SNR, CNR, CTP and CT angiography subjective image quality evaluation between both groups were not statistically significant (P>0.05); the diagnosis rate of the acute infarcts between the two groups was not significantly different; while the ED and iodine intake in group B (dual low-dose group) were lower than group A. In conclusion, combination of low tube voltage and iterative reconstruction technique, and application of low-concentration contrast agent (270 mg I/ml) in whole brain CTP examination reduced ED and iodine intake without compromising image quality, thereby reducing the risk of contrast-induced nephropathy.

Contrast Dose and Radiation Dose Reduction in Abdominal Enhanced Computerized Tomography Scans with Single-phase Dual-energy Spectral Computerized Tomography Mode for Children with Solid Tumors.

Background:Contrast dose and radiation dose reduction in computerized tomography (CT) scan for adult has been explored successfully, but there have been few studies on the application of low-concentration contrast in pediatric abdominal CT examinations. This was a feasibility study on the use of dual-energy spectral imaging and adaptive statistical iterative reconstruction (ASiR) for the reduction of radiation dose and iodine contrast dose in pediatric abdominal CT patients with solid tumors.Methods:Forty-five patients with solid tumors who had initial CT (Group B) and follow-up CT (Group A) after chemotherapy were enrolled. The initial diagnostic CT scan (Group B) was performed using the standard two-phase enhanced CT with 320 mgI/ml concentration contrast, and the follow-up scan (Group A) was performed using a single-phase enhanced CT at 45 s after the beginning of the 270 mgI/ml contrast injection using spectral mode. Forty percent ASiR was used for the images in Group B and monochromatic images with energy levels ≥60 keV in Group A. In addition, filtered back-projection (FBP) reconstruction was used for monochromatic images <60 keV in Group A. The total radiation dose, total iodine load, contrast injection speed, and maximum injection pressure were compared between the two groups. The 40 keV and 60 keV spectral CT images of Group A were compared with the images of Group B to evaluate overall image quality.Results:The total radiation dose, total iodine load, injection speed, and maximum injection pressure for Group A were decreased by 19%, 15%, 34.4%, and 18.3%, respectively. The optimal energy level in spectral CT for displaying the abdominal vessels was 40 keV. At this level, the CT values in the abdominal aorta and its three branches, the portal vein and its two branches, and the inferior vena cava were all greater than 340 hounsfield unit (HU). The abdominal organs of Groups A and B had similar degrees of absolute and relative enhancement (t = 0.36 and −1.716 for liver, −0.153 and −1.546 for pancreas, and 2.427 and 0.866 for renal cortex, all P > 0.05). Signal-to-noise ratio of the abdominal organs was significantly lower in Group A than in Group B (t = −8.11 for liver, −7.83 for pancreas, and −5.38 for renal cortex, all P < 0.05). However, the subjective scores for the 40 keV (FBP) and 60 keV (40% ASiR) spectral CT images determined by two radiologists were all >3, indicating clinically acceptable image quality.Conclusions:Single-phase, dual-energy spectral CT used for children with solid abdominal tumors can reduce contrast dose and radiation dose and can also maintain clinically acceptable image quality.

Overall evaluability of low dose protocol for computed tomography angiography of thoracic aorta using 80kV and iterative reconstruction algorithm using different concentration contrast media.

Multidetector Computed Tomography Angiography (MDCTA) is presently the imaging modality of choice for aortic disease. However, the effective radiation dose and the risk related to the use of contrast agents associated with MDCTA is an issue of concern. Aim of this study was to assess image quality of a low dose ECG-gated MDCTA of thoracic aorta using different concentration contrast media without tailored injection protocol. Two-hundred patients were randomised into four different scan protocols: Group A (Iodixanol 320 and 80 Kvp tube voltage), Group B (Iodixanol 320 and 100Kvp tube voltage), Group C (Iomeprol 400 and 80Kvp tube voltage) and Group D (Iomeprol 400 and 100Kvp tube voltage). Image quality, noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and effective dose (ED) were compared among groups. No significant differences in image noise, SNR and CNR between groups with the same tube voltage. Significant differences in SNR and CNR were found among groups with 80kV versus groups using 100kV but without differences in terms of image quality. ED was significantly lower in groups with 80kV. Multidetector Computed Tomography Angiography protocols using 80kV and low concentration contrast media are feasible without need of tailored injection protocols.

Prospective ECG-triggering cardiac CT for infants with complex congenital heart disease using low-dose contrast medium, low tube voltage, and adaptive statistical iterative reconstruction

To demonstrate the clinical value of prospective electrocardiography (ECG)-triggered cardiac computed tomography (CT) with low concentration contrast medium, low tube voltage, and adaptive statistic iterative reconstruction (ASIR) to reduce both radiation and contrast dose in examining infants with complex congenital heart disease (CHD). Forty-four consecutive infants (19 male, 25 female, age: 8.06±4.33 months, weight: 7.31±1.36kg) with complex CHD underwent prospective ECG-triggered low-dose cardiac CT using 80 kVp and 120mA. The contrast agent was iodixanol (270mg iodine/ml, Visipaque, GE Healthcare, Co. Cork, Ireland). Cardiac CT images were reconstructed with 70% ASIR. The quantitative CT image quality was assessed by image noise in adipose tissue and contrast-to-noise ratio (CNR) in the aorta. The qualitative image analysis was performed on a five-point grading scale by two independent reviewers and interobserver variability was calculated. The results of 32 CT examinations were also compared with the available surgical results for diagnostic accuracy evaluation. The effective dose was 0.55±0.10mSv for the patient population. The iodine load was 3.95±0.73g iodine. Image noise in adipose tissue was 16.24±1.42 HU and CNR in aorta was 21.90±7.10. All images were acceptable for diagnosis with an average score of 4.52±0.38 and good agreement between reviewers (kappa=0.75). Compared to the surgery results in 32 cases, CT was 97% and 88% accurate diagnosing extracardiac and intracardiac defects, respectively. Prospective ECG-triggered cardiac CT using 80 kVp, low-concentration iodinated contrast agent (270mg iodine/ml) and 70% ASIR reconstruction provides excellent image quality and accurate diagnosis for complex congenital heart disease in infants with reduced contrast medium dose and low radiation dose.

Application of low concentration contrast medium in spectral CT imaging for CT portal venography.

To investigate the effect of low-concentration contrast medium on spectral computed tomography (CT) image quality for portal venography CT. 150 patients with suspected portal diseases were divided into three groups and had spectral CT examination using aGE Discovery CT 750 HD scanner. The patients in three groups were injected with different concentrations of iodine (350 mgI/mL, 315 mgI/mL and 280 mgI/mL) at an injection rate of 4.0-5.0 mL/s with 1.2 mL/kg (body weight) of contrast medium, respectively. During the portal vein imaging phase, 0.625 mm-slice-thickness monochromatic images and optimal monochromatic images were obtained. Optimal keV mono-energy was achieved using the optimal contrast-to-noise ratio (CNR) in the portal vein relative to the erector spinae muscle. Volume rendering and maximum intensity projection methods were applied to generate portal venography. The CT values and standard deviations were measured at the portal vein, the erector spinae muscle, and the abdomen fat, respectively. These values were used to calculate the signal-to-noise ratio (SNR); while CNR was calculated using CT values of the portal vein and erector spinae muscle. The overall imaging quality was evaluated on afive-point scale by two radiologists with at least five years' experience. Comparisons among the three groups were performed using One-Way ANOVA test. Monochromatic images at 50-53 keV demonstrated the best CNR for both the portal vein and erector spinae muscle. SNR and CNR of images with different contrast medium concentrations were similar (P > 0.05). The five-point scores were also similar (P > 0.05) for the three groups. The total iodine intake at 280 mgI/mL was 25.4% lower than that at 350 mgI/mL. Spectral CT with monochromatic images at 50-53 keV allows significant reduction in iodine load while improving portal vein signal intensity and maintaining image quality.

Use of low tube voltage and low contrast agent concentration yields good image quality for aortic CT angiography

To evaluate the impact of a "double-low" imaging protocol (low tube voltage and low contrast agent concentration) on image quality and radiation dose for aortic computed tomography (CT) angiography (CTA). This was a prospective study of 72 patients undergoing aortic CTA. They were randomised to the double-low and conventional CT (control) groups (n=36/group). Axial imaging was performed in the study group, and control patients were scanned with the conventional protocol. Double-low parameters were: 80-100kV, 200mAs, 128×0.625 collimation, 1-mm section thickness, 0.5-mm increments, 300mm field of view (FOV), iohexol (300mg iodine/ml, 1-1.5ml/kg, injected at 4-5ml/s). Control CT parameters were: 120kV, 200-300mAs, iopamidol (370mg iodine/ml; 1-1.5ml/kg, injected at 4-5ml/s); the remaining parameters were the same as in the double-low group. Image noise and quality scores of the double-low and control groups were 15.05±1.53 versus 14.67±1.53 and 3.52±0.51 versus 3.44±0.5 (both p>0.05), respectively. Radiation dose was 56% lower in the double-low group compared to control patients (6.76±1.08 versus 15.48±1.01mSv, p<0.001). Iodine intake per-capita in the double-low group was 18% lower compared to the control group (300.25±7.2 versus 367.86±5.54 mgI/kg, p<0.001). The "double-low" technique for aortic CTA significantly reduced the doses of radiation and iodine contrast agent, while maintaining good image quality.

Application of 80-kVp tube voltage, low-concentration contrast agent and iterative reconstruction in coronary CT angiography: evaluation of image quality and radiation dose

To evaluate image quality and radiation dosage in coronary CT angiography using 80-kVp tube voltage combined with low-concentration contrast media (CM) and iterative reconstruction (IR) for coronary CT angiography (CCTA) and employing dual-source CT without heart-rate control. 154 patients were randomly assigned to Group A (Control Group, 120-kVp tube voltage, high-concentration CM and filtered back projection reconstruction) and Group B (Low-Dose Group, 80kVp, low-concentration CM and iterative construction). Two experienced radiologists double-blindly evaluated the following parameters: CT attenuation, signal-noise ratio (SNR), contrast-noise ratio (CNR), radiation dose, size-specific dose estimates (SSDE) and total iodine intake. Pearson correlation analysis was used to assess the relationship between SSDE and BMI. 98.1% vessel segments in Group A and 97.6% in Group B passed diagnostics, indicating no significant differences; the average aorta scores and CT attenuation values showed no significant differences between groups. Similar SNR and CNR results were obtained for the two groups, although values were slightly lower in Group A compared with Group B. The Effective Dose in Group B was 63% lower than that in Group A (P<.001). SSDE results were significantly different between the two groups (P<.001) but did not correlate with BMI. Finally, the total iodine intake in Group B was 22.9% lower than that in Group A. Coronary CTA conducted with a low tube voltage of 80kVp, a low-concentration CM and IR without heart rate control can achieve images of similar quality to those obtained using standard procedures, significantly reducing the associated radiation dose and iodine intake.

Application of low dose radiation and low concentration contrast media in enhanced CT scans in children with congenital heart disease.

The aim of this study was to explore the feasibility of using low dose radiation and low concentration contrast media in enhanced CT examinations in children with congenital heart disease. Ninety patients with congenital heart disease were randomly divided into three groups of 30 patients each who underwent contrast-enhanced cardiac scans on a Discovery CT750 HD scanner. Group A received 270mgI/mL iodixanol, and group B received 320mgI/mL iodixanol contrast media and was scanned with prospective ECG triggering mode. Group C received 320mgI/mL iodixanol and was scanned with conventional retrospective ECG gating mode. The same weight-based contrast injection protocol was used for all three groups. Images were reconstructed using a 30% adaptive statistical iterative reconstruction (ASIR) algorithm and a 50% ASIR in groups A and B and a 30% ASIR in group C. The subjective and objective image quality evaluations, diagnostic accuracies, radiation doses and amounts of contrast media in the three groups were measured and compared. All images in the three groups met the diagnostic requirements, with the same diagnostic accuracy and image quality scores greater than 3 in a 4-point scoring system. However, ventricular enhancement and the objective noise, signal-to-noise ratio, contrast-to-noise ratio and subjective image quality scores in group C were better than those in groups A and B (all P<.001). The effective radiation dose in groups A and B was 84% lower than that in group C (P<.001); group A received the lowest contrast dose (14% lower than that of groups B and C). Enhanced CT scan images with low dose radiation and low concentration contrast media can meet the diagnostic requirements for examining children with congenital heart disease while reducing the potential risk of radiation damage and contrast-induced nephropathy.

Coronary CT angiography with 80 kV tube voltage and low iodine concentration contrast agent in patients with low body weight

BackgroundCoronary CT angiography (CTA) is gaining widespread acceptance for the non-invasive evaluation of coronary arteries. However, radiation exposure and administration of iodinated contrast agents are still reasons of some concern. The 80 kV tube voltage increases the attenuation of iodine, allowing to use lower iodine concentration contrast agents for coronary CTA. ObjectiveWe evaluated the diagnostic accuracy of coronary CTA performed with 64-slice scanner, 80 kV tube voltage, iterative reconstruction algorithm and ultra-low concentration contrast medium to reduce iodine load and radiation dose. MethodsWe enrolled 45 patients with low body weight and indication for elective invasive coronary angiography (ICA). All patients received an 80 ml bolus of Iodixanol-270 at an infusion rate of 5 mL/s and underwent coronary CTA (80 kV and 500–550 mA) with prospective ECG-triggering. Image quality score, type of artifacts, coronary CTA evaluability, diagnostic accuracy and radiation exposure were assessed. ResultsPre-test probability of CAD was low-to-intermediate (48%). Accordingly, the prevalence of obstructive CAD was 47% (21 out of 45 patients). Most (93%) of the patients were pre-treated with intravenous metoprolol before scanning and achieved a heart rate suitable for prospective ECG-triggering coronary CTA (53 ± 3 bpm). The mean effective dose and iodine load were 1.1 ± 0.4 mSv and 21.6 gI, respectively. We rated 443 out of 720 coronary segments as being of excellent image quality. In a segment-based model, coronary evaluability (number of coronary segments evaluable/total number of coronary segments), was 97% (699/720 segments). In a segment-based analysis, sensitivity, specificity, positive predictive value, negative predictive value and accuracy for >50% coronary stenosis identification vs. ICA were 89%, 99%, 89%, 99% and 99%, respectively. In a patient-based analysis, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 94%, 89%, 83%, 96% and 91%, respectively. ConclusionsIn patients with low body weight, image quality and diagnostic accuracy of ultra-low radiation dose and low-iodine load coronary CTA are good and similar to values reported in the literature for standard tube voltage and iodine load protocols.

Large-aperture X-ray refractive lens

An X-ray refractive lens with an enlarged aperture (multilens) is developed and a procedure for obtaining images using this lens and methods of their processing are proposed. The multilens is compared with conventional X-ray refractive lenses, and the method of processing is compared to known techniques. It is shown that the proposed multilens can receive X-ray images with an aperture ratio of two to three orders of magnitude greater than a conventional X-ray refractive lens. Possible applications of the multilens are considered. Most attractive is use of the proposed multilens for imaging biological objects with a very low concentration of contrast agent. Quantitative estimates show that images of such objects can be obtained using modern synchrotron-radiation sources with a resolution of approximately 1 μm in hundreds of seconds.

Evaluation of the Low Tube Voltage in the Computed Tomography Scan Technique using a Low Concentration Contrast Agent

Evaluation of the Low Tube Voltage in the Computed Tomography Scan Technique using a Low Concentration Contrast Agent

Coronary Computed Tomographic Angiography at Low Concentration of Contrast Agent and Low Tube Voltage in Patients with Obesity:: A Feasibility Study

Using lower tube voltage can reduce the exposure to radiation and the dose of contrast agent. However, lower tube voltage is often linked to more noise and poor image quality, which create a need for more effective technology to resolve this problem. To explore the feasibility of coronary computed tomographic angiography (CCTA) in patients with obesity at low tube voltage (100 kV) and low contrast agent concentration (270 mg/mL) using iterative reconstruction. A total of 48 patients with body mass index greater than 30 kg/m(2) were included and randomly divided into two groups. Group A received a traditional protocol (iopromide 370 mg/mL + 120 kV); group B received a protocol with low tube voltage (100 kV), low contrast agent concentration (270 mg/mL), and iterative reconstruction. The effective dose (ED), average attenuation values, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), the figure of merit (FOM), image quality scores, and the total iodine intake were compared. No significant differences in average CT attenuations, SNR, CNR, and subjective scores were noticed between the two groups (P > 0.05), whereas the FOM of group B was significantly higher than that of group A. Effective radiation dose, total iodine, and iodine injection rate in group B were lower than those of group A (P <0.01). In patients with obesity, isotonic contrast agent with low iodine concentration and low-dose CCTA were feasible. Substantial reduction in radiation dose and the iodine intake could be achieved without compromising the image quality.