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PURPOSE: To compare image quality, iodine intake, and radiation dose in overweight and obese patients undergoing abdominal computed tomography (CT) enhancement using different scanning modes and contrast medium. METHODS: Ninety overweight and obese patients (25 kg/m2≤body mass index (BMI)< 30 kg/m2 and BMI≥30 kg/m2) who underwent abdominal CT-enhanced examinations were randomized into three groups (A, B, and C) of 30 each and scanned using gemstone spectral imaging (GSI) +320 mgI/ml, 100 kVp + 370 mgI/ml, and 120 kVp + 370 mgI/ml, respectively. Reconstruct monochromatic energy images of group A at 50–70 keV (5 keV interval). The iodine intake and radiation dose of each group were recorded and calculated. The CT values, contrast-to-noise ratios (CNRs), and subjective scores of each subgroup image in group A versus images in groups B and C were by using one-way analysis of variance or Kruskal–Wallis H test, and the optimal keV of group A was selected. RESULTS: The dual-phase CT values and CNRs of each part in group A were higher than or similar to those in groups B and C at 50–60 keV, and similar to or lower than those in groups B and C at 65 keV and 70 keV. The subjective scores of the dual-phase images in group A were lower than those of groups B and C at 50 keV and 55 keV, whereas no significant difference was seen at 60–70 keV. Compared to groups B and C, the iodine intake in group A decreased by 12.5% and 13.3%, respectively. The effective doses in groups A and B were 24.7% and 25.8% lower than those in group C, respectively. CONCLUSION: GSI +320 mgI/ml for abdominal CT-enhanced in overweight patients satisfies image quality while reducing iodine intake and radiation dose, and the optimal keV was 60 keV. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of low tube voltage (100 kV) combined with adaptive statistical iterative reconstruction-V (ASIR-V) on the visualization and image quality of the Adamkiewicz artery (AKA). Methods: One hundred patients were prospectively enrolled and randomly assigned into two groups (both n = 50). Group A (100 kV) was reconstructed with filtered back projection (FBP) and ASIR-V from 10% to 100% with 10% intervals. Group B (120 kV) was only reconstructed with FBP. The objective image quality was evaluated by using CT values of the aorta (CTAorta), background noise, signal-to-noise ratio of the descending aorta (SNRAorta), and contrast-to-noise ratio of the spinal cord (CNRSpinal cord). The subjective image quality and visualization scores of the AKA were assessed on a 5-point scale. Results: CTAorta was significantly higher in Group A than in Group B (p < 0.001). When ASIR-V weights were ≥60%, significant differences were found in the background noise, SNRAorta, and CNRSpinal cord between the two groups (all p < 0.05). In Group A, compared with FBP, the subjective score gradually increased as ASIR-V increased to 80%, which decreased when ASIR-V exceeded 80%. The visualization scores of the AKA (≥60%) and the ability to detect vessel continuity (≥80%) gradually increased as the ASIR-V weights increased (p < 0.05). The effective radiation dose was reduced by about 40.36% in Group A compared to Group B. Conclusions: compared with conventional scanning protocol, using a combination of low tube voltage (100 kV) and 80% ASIR-V protocol could not only increase the visualization of the AKA, but also improve image quality and reduce the radiation doses. [ABSTRACT FROM AUTHOR]

Background: Contrast-induced nephropathy (CIN) is an adverse reaction associated with the use of intravenous contrast media (CM). Purpose: To investigate the impact of low tube voltage settings on single-energy computed tomography (SECT) and rapid kV switching dual-energy CT (DECT) with reduced concentrations of iodinated CM. Material and Methods: A phantom containing four different concentrations of CM (original concentration CM, 20%, 40%, and 60% reductions) was scanned using SECT mode with varying tube voltages (70, 80, 100, and 120 kVp) and DECT mode through reconstructing monoenergetic energy (50 keV and 70 keV) images. ATCM system with different noise index (NI) settings were set, and the images were reconstructed using ASiR-V. Image quality were measured for individual phantom sizes and protocols and compared to a reference protocol for SECT of 120 kVp, NI = 18, threshold contrast enhancement ≥280 HU, and CNR ≥17. Results: Tube voltage settings of 70 kVp together with 40% reduction in the iodinated CM is suitable for small phantom size, those of 80 kVp and 20% reduction is suitable for the medium and large sizes. This allows radiation doses to be reduced by 12%–30%. Values of CNR and contrast for DECT are better than those for SECT with the same NI setting. Conclusion: Diagnostic reference of image quality can be maintained by using SECT with lower tube voltage and DECT with reductions of iodinated CM concentration and radiation dose. Therefore, the NI setting can be increased when DECT is used to achieve a similar image quality. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of low tube voltage (100 kV) combined with adaptive statistical iterative reconstruction-V (ASIR-V) on the visualization and image quality of the Adamkiewicz artery (AKA). Methods: One hundred patients were prospectively enrolled and randomly assigned into two groups (both n = 50). Group A (100 kV) was reconstructed with filtered back projection (FBP) and ASIR-V from 10% to 100% with 10% intervals. Group B (120 kV) was only reconstructed with FBP. The objective image quality was evaluated by using CT values of the aorta (CTAorta), background noise, signal-to-noise ratio of the descending aorta (SNRAorta), and contrast-to-noise ratio of the spinal cord (CNRSpinal cord). The subjective image quality and visualization scores of the AKA were assessed on a 5-point scale. Results: CTAorta was significantly higher in Group A than in Group B (p < 0.001). When ASIR-V weights were ≥60%, significant differences were found in the background noise, SNRAorta, and CNRSpinal cord between the two groups (all p < 0.05). In Group A, compared with FBP, the subjective score gradually increased as ASIR-V increased to 80%, which decreased when ASIR-V exceeded 80%. The visualization scores of the AKA (≥60%) and the ability to detect vessel continuity (≥80%) gradually increased as the ASIR-V weights increased (p < 0.05). The effective radiation dose was reduced by about 40.36% in Group A compared to Group B. Conclusions: compared with conventional scanning protocol, using a combination of low tube voltage (100 kV) and 80% ASIR-V protocol could not only increase the visualization of the AKA, but also improve image quality and reduce the radiation doses.

Copyright of Imaging Science & Photochemistry is the property of Imaging Science & Photochemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: The low-tube-voltage scan generally needs a higher tube current than the conventional 120 kVp to maintain the image noise. In addition, the low-tube-voltage scan increases the photoelectric effect, which increases the radiation absorption in organs. Purpose: To compare the organ radiation dose caused by iodine contrast medium between low tube voltage with low contrast medium and that of conventional 120-kVp protocol with standard contrast medium. Material and Methods: After the propensity-matching analysis, 66 patients were enrolled including 33 patients with 120 kVp and 600 mgI/kg and 33 patients with 80 kVp and 300 mgI/kg (50% iodine reduction). The pre- and post-contrast phases were assessed in all patients. The Monte Carlo simulation tool was used to simulate the radiation dose. The computed tomography (CT) numbers for 10 organs and the organ doses were measured. The organ doses were normalized by the volume CT dose index, and the 120-kVp protocol was compared with the 80-kVp protocol. Results: On contrast-enhanced CT, there were no significant differences in the mean CT numbers of the organs between 80-kVp and 120-kVp protocols except for the pancreas, kidneys, and small intestine. The normalized organ doses at 80 kVp were significantly lower than those of 120 kVp in all organs (e.g. liver, 1.6 vs. 1.9; pancreas, 1.5 vs. 1.8; spleen, 1.7 vs. 2.0) on contrast-enhanced CT. Conclusion: The low tube voltage with low-contrast-medium protocol significantly reduces organ doses at the same volume CT dose index setting compared with conventional 120-kVp protocol with standard contrast medium on contrast-enhanced CT. [ABSTRACT FROM AUTHOR]

Objective To investigate the feasibility of 80 kV tube voltage with adaptive statistical iterative :reconstruction Veo (ASIR -V) algorithm for .reducing the dosage of radiation exposure and amount of contrast agent in computed tomography portal venography (CTPV). Methods Sixty patients undergoing CTPV were randomly divided .into two groups using 120 kV tube voltage, 450 mg I/kg contrast agent, and filtered hack projection (FBP) reconstruction in group A; 80 kV tube voltage, 350 mg I/kg contrast agent, and 40% ASIR-V reconstruction in group B. The CT values and standard deviation (SD) of the main portal vein (MPV), left branch of portal vein (LPV), right branch of portal vein (RPV) were measured to calculate the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The image quality was subjectively scored by two experienced radiologists using a 5-point system. The effective dose (ED) was calculated. Measurements were statistically compared using the independent sample t test and Mann-Whitney l) test. Results There was no significant difference in the general data between the two groups (P>0.05). Group B had significantly (P<0.001) lower radiation dose (2.14±0.21) mSv and amount of contrast agent (22.14±2.59) g[ than that of group A (5.54±l.15) mSv, (28.19±4.04) gl with 61 % reduction in El) and 21.5% reduction in amount of contrast agent. 'Ibe CT values of MPV, LPV and RPV in group B were significantly higher than those in group A (P<0.05). The SD values of portal veins in group B were significantly lower (P<0.001) whereas the SNR and CNR values were significantly higher than those in group A (P<0.001 ). The image quality scores of two radiologists had excellent agreement (Kappa>0.80, P<0.001) with significantly higher scores in group B (4.20±0.71 and 4.23±0.68) than those of group A (3.37±0.49 and 3.43±0.50), and no significant difference between the scores by two radiologists (P<0.05). Conclusion ASIR-V with 80 kV low tube voltage significantly reduces radiation dose and amount of contrast a.gent with better image quality in CTPV. [ABSTRACT FROM AUTHOR]

To compare the radiation dose, diagnostic accuracy, and the resultant ablation procedures using 80 and 120-kVp cardiac computed tomography angiography (CCTA) protocols with the same contrast-to-noise ratio in patients scheduled for atrial fibrillation (AF) ablation. This retrospective study was performed following institutional review board approval. We divided 140 consecutive patients who had undergone CCTA using a 64-MDCT scanner into two equal groups. Standard deviation (SD) of the CT number was set at 25 Hounsfield units (HU) for the 120-kVp protocol. To facilitate a reduction in radiation dose it was set at 40 HU for the 80 kVp protocol. We compared the two protocols with respect to the radiation dose, the diagnostic accuracy for detecting left atrial appendage (LAA) thrombi, matching for surface registration, and the resultant ablation procedures. At 120 kVp, the dose length product (DLP) was 2.2 times that at 80 kVp (1269.0 vs 559.0 mGy cm, p < 0.01). The diagnostic accuracy for thrombus detection was 100% using both protocols. There was no difference between the two protocols with respect to matching for surface registration. The protocols did not differ with respect to the subsequent time required for the ablation procedures and the ablation fluoroscopy time, and the radiation dose (p = 0.54, 0.33, and 0.32, respectively). For the same CNR, the DLP at 80 kVp (559.0 mGy cm) was 56% of that delivered at 120 kVp (1269.0 mGy cm). There was no reduction in diagnostic accuracy. Maintaining CNR allows for a reduction in the radiation dose without reducing the image quality. [ABSTRACT FROM AUTHOR]

This study's primary goal is to assess the image quality and radiation dose of the low-dose 80kV computed tomography pulmonary angiogram (CTPA) protocol compared to the standard 100kV CTPA protocol for the assessment of pulmonary embolism (PE). The study consisted of 100 patients who had clinically suspected pulmonary embolism and required a CTPA. Patients underwent imaging with a 320-row multi-detector Toshiba Aquilion One Genesis Edition in the absence of the proprietary radiation reduction software known as forward projected model-based Iterative Reconstruction Solution (commercial acronym 'FIRST'). Participants were divided into two groups: A and B. Group A was composed of 50 patients who were allocated to standard CT protocol using a 100 kV exposure setting and all other settings set as a standard by the manufacturer. Group B was composed of 50 patients who were allocated to a CTPA with a low-dose 80kV protocol, standard deviation level 8, an effective mAs of 258, reconstruction algorithm-kernel FC 51 within the lung window, and tube current modulation. A considerable decrease in radiation dose was observed with the low-dose CTPA protocol. The mean radiation dose was also decreased by 66% while using the 80kV protocol than when utilising a standard 100kV technique; this was achieved without compromising this study's diagnostic value. Furthermore, the contrast enhancement was considerably more significant, up to 40% higher when using 80kV. The study found that a low tube voltage of 80kV CTPA protocol resulted in a considerable decrease in radiation dose and improved contrast enhancement without sacrificing the examinations' diagnostic utility.

Purpose: To compare the image quality of multiphasic (arterial, portal, and equilibrium phases) dynamic computed tomography (CT) of the abdomen obtained by a low tube voltage (70kVp) in combination with a half-dose iodine load using low-concentration contrast agent in high tube output dual-source CT with a standard tube voltage (120kVp) and full-dose iodine load using the same group of adult patients. Methods: Fifty-five patients who underwent both low-tube-voltage (70kVp) abdominal CT with a half-dose iodine load and standard-tube-voltage (120kVp) CT with a full-dose iodine load were analyzed. The mean CT values and signal-to-noise ratio (SNR) of the liver, aorta and portal veins were quantitatively assessed. In addition, the contrast enhancement of the abdominal organs and overall image quality were qualitatively evaluated. Results: The mean CT values and SNR of the liver parenchyma were significantly higher in 70-kVp protocol than in 120-kVp protocol in all 3 phases (p = 0.018 ~ < 0.001). Regarding the qualitative analysis, the overall image quality in the 70-kVp protocol was significantly better than in the 120-kVp protocol in all 3 phases (p < 0.001). In addition, the contrast enhancement scores of the liver parenchyma and hepatic vein in the equilibrium phase were also significantly higher in the 70-kVp protocol than in the 120-kVp protocol (p < 0.001). Conclusion: A low tube voltage (70kVp) in combination with a half-dose iodine load using a low-concentration contrast agent and an iterative reconstruction algorithm in high tube output dual-source CT may improve the contrast enhancement and image quality in multiphasic dynamic CT of the abdomen in patients under 71 kg of body weight. [ABSTRACT FROM AUTHOR]

Background: Low peak kilovoltage (kVp) computed tomography (CT) may be used to reduce contrast medium doses in patients at risk of contrast medium-induced acute kidney injury if image noise can be controlled by increasing X-ray tube loading (mAs). Purpose: To evaluate objective and subjective image quality in 80-kVp CT with reduced contrast medium dose and compensated mAs for unchanged image noise in patients with estimated glomerular filtration rate <45 mL/min compared with the standard 120-kVp protocol. Material and Methods: 80-kVp CT with 300 mg I/kg in 40 patients (body mass index 18–32 kg/m2, glomerular filtration rate <45 mL/min) and 120-kVp CT with 500 mg I/kg in 40 patients (body mass index = 17–30 kg/m2, glomerular filtration rate ≥45 mL/min) was compared on mean hepatic attenuation, image noise, contrast medium enhancement, signal-to-noise ratio, contrast-to-noise ratio, effective radiation dose, and subjective image quality. Results: There were no significant differences regarding median hepatic post-contrast attenuation, image noise, contrast medium enhancement, signal-to-noise ratio, contrast-to-noise ratio, or effective dose between the 80-kVp and 120-kVp cohorts: 114/110 HU; 14/14 HU; 57/53 HU; 8.0/7.4; 3.8/3.5; and 5.3/5.9 mSv, respectively. However, subjective image visual grading showed statistically significantly inferior scores for 80 kVp for six of eight items. After exclusion of seven inferior examinations not caused by the chosen kVp technique, only three items showed inferior scores for 80 kVp. Only 5% of gradings regarding overall image quality were <3 of 5 points. Conclusion: Despite lower subjective image quality, objective data indicate that 80-kVp CT with reduced contrast medium doses and compensated mAs may have the potential to provide satisfactory diagnostic quality in patients with body mass index <30 kg/m2, which could benefit patients at risk of contrast medium-induced acute kidney injury. [ABSTRACT FROM AUTHOR]

Background: Hepatic computed tomography (CT) with decreased peak kilovoltage (kVp) may be used to reduce contrast medium doses in patients at risk of contrast-induced acute kidney injury (CI-AKI); however, it increases image noise. To preserve image quality, noise has been controlled by X-ray tube loading (mAs) compensation (TLC), i.e. increased mAs. Another option to control image noise would be to use iterative reconstructions (IR) algorithms without TLC (No-TLC). It is unclear whether this may preserve image quality or only reduce image noise. Purpose: To evaluate image quality of 80 kVp hepatic CT with TLC and filtered back projection (FBP) compared with 80 kVp with No-TLC and IR algorithms (SAFIRE 3 and 5) in patients with eGFR <45 mL/min. Material and Methods: Forty patients (BMI 18–32 kg/m2) were examined with both protocols following injection of 300 mg I/kg. Hepatic attenuation, image noise, enhancement, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and subjective image quality were evaluated for each patient. Results: Comparing TLC/FBP with No-TLC/IR-S5, there were no significant differences regarding hepatic attenuation, image noise, enhancement, SNR and CNR: 114 vs. 115 HU, 14 vs. 14 HU, 55 vs. 57 HU, 8.0 vs. 8.4, and 3.8 vs. 4.0 in median, respectively. No-TLC/IR-S3 resulted in higher image noise and lower SNR and CNR than TLC/FBP. Subjective image quality scoring with visual grading showed statistically significantly inferior scores for IR-S5 images. Conclusion: CT of 80 kVp to reduce contrast medium dose in patients at risk of CI-AKI combined with IR algorithms with unchanged tube loading to control image noise does not provide sufficient diagnostic quality. [ABSTRACT FROM AUTHOR]

Copyright of CT Theory & Applications is the property of Editorial Department of CT Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: The use of weight-adapted pediatric computed tomography (CT) tube voltage protocols has been suggested, but a consensus standard has not been established and clinical available studies are not sufficient. Purpose: To determine the best tube voltage for low dose abdominal CT imaging in children. Material and Methods: Eighty-seven cases who needed three CT exams in a 1–3-month interval between scans were enrolled (mean age = 4.69 ± 3.20 years). The three scans were performed with three different tube voltages at 80 kV, 100 kV, and 120 kV, keeping the same radiation dose and same contrast injection protocol. Patients were divided into five groups for analysis based on their body weight. The subjective image quality of the three exams were evaluated using a 4-point scale (4 being the best) for image noise and image quality. The objective evaluation in terms of CT values and standard deviation in aorta, liver, spleen, pancreas, and kidney were measured to calculate the degree of enhancement and contrast-to-noise ratio (CNR) of organs. One-way ANOVA was used to compare the subjective and objective image quality with respect to different tube voltages and different patient weights. Result: The 80-kV tube voltage provided the highest overall enhancement and CNR for the entire patient population and the best objective image quality for the 6.1–28.0 kg subgroup. Conclusion: Patient weight-dependent tube voltage selection maximizes image quality for abdominal enhanced CT in children. The optimal tube voltage for children with weight <28 kg is 80 kV; higher voltages should be selected for children weighing 28.1–50.0 kg. [ABSTRACT FROM AUTHOR]

Objective To explore the feasibility of low-voltage combined with fast iterative reconstruction technique in CT virtual colonoscopy. Methods 60 patients were randomly divided into two groups of conventional 120 kV tube voltage (30) and 100 kV tube voltage combined with fast iterative reconstruction algorithm (30). Enhanced scanning was performed on all the data collected for iDose algorithm level 1 -6 reconstruction and standard algorithm reconstruction. Image quality score, noise (SD), SNR, CNR, CTDIvol, DLP, and ED were compared for image quality and radiation dose evaluation. Results The image quality score using 100 kV was not significantly lower than that of 120 kV tube voltage (P > 0.05) whereas the quantitative parameters were significantly better with 100 kV (P<0.05). Conclusion 100 kV tube voltage combined with fast iterative reconstruction algorithm is feasible for CT virtual colonoscopy with adequate image quality and lower radiation dose. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the image quality of a double-low protocol (low tube voltage and low iodine concentration) for abdominal CT in children. Materials and methods: The double-low protocol was compared to the conventional protocol in pediatric patients weighing less than 40 kg from May 2016 to December 2016. Double-low protocol (Group A, n = 18): tube voltage, 70 kVp; and iodine concentration,: 250 mgI/mL versus Conventional protocol (Group B, n = 13): tube voltage, 80–100 kVp; and iodine concentration, 350 mgI/mL. Mean attenuation, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were compared between the two groups. Image contrast, noise, beam-hardening artifacts, and overall image quality were subjectively scored. Reader performance for correctly differentiating two groups by visual assessment was evaluated. Radiation dose and total iodine load were recorded. Results: The mean attenuations of the portal vein and liver and the mean image noise in Group A were higher than in Group B (p = 0.04, 0.03, 0.004, respectively). The mean SNR and CNR of the main portal vein and liver were lower in Group A without any statistically significant difference. There were no statistically significant differences between the two groups in qualitative analysis (image contrast, image noise, and overall image quality) with substantial agreement between the reviewers (weighted kappa values; 0.59–0.76). Significantly diminished radiation dose and iodine load were observed in Group A compared with Group B (25.0%, 36.8% reduction; p = 0.007, 0.006, respectively). Conclusion: The double-low protocol was feasible for pediatric abdominal CT and reduced both radiation dose and iodine load, while maintaining image quality. [ABSTRACT FROM AUTHOR]

To explore the feasibility of low tube voltage, small dose and low concentration of contrast media combined iDose in head and neck CTA, 60 cases undergone head and neck CTA were randomly and equally divided into experimental group and control group. 100 kV lube voltage and 50mL contrast agent with 270 mgI/mL concentration combined with rapid iterative reconstruction algorithm were used in the experimental group, while 120 kV tube voltage and 50mL contrast agent with 370 mgI/mL concentration were used in the control group. The CT value, noise (SD) , CNR, SNR, image quality score, CTDIvol and DTP of the two groups were compared, and the image quality and radiation dose were evaluated. The results showed that the CT value of the cervical vessels in the experimental group was slightly lower than that of the control group, and the CT value of the intracranial vessels was slightly higher than that of the control group. The image quality of the two groups met the clinical diagnostic needs. The noise (SD) of the experimental group combined with iDose technique was lower than that of the control group, while the SNR and CNR were higher than those of the control group. The radiation dose of 理 the experimental group was significantly lower than that of the control group, and the CTDIvol and DPP decreased by about 51% and 56%, respectively. Therefore, low tube voltage, small contrast media dose and low concentration combined with rapid iterative reconstruction (iDose) for head and neck CTA examination is feasible. The image quality can fully meet the clinical diagnostic needs, and the radiation dose is significantly reduced. [ABSTRACT FROM AUTHOR]

Background: Using a low volume of contrast medium and tube voltage may enhance the opacification of pulmonary arteries and thrombus detection without decreasing the image quality. In addition, this protocol can also ensure that exposure of the patient to the contrast medium and radiation dose may be significantly reduced. Objectives: The purpose of this study was to investigate the efficiency of low tube voltage and low dose iodine-based contrast medium in computed tomography pulmonary angiography (CTPA) and optimize its use in the diagnosis of pulmonary thromboembolism (PTE). Patients and Methods: We included a total of 100 patients undergoing CTPA with an initial diagnosis of PTE into two groups: group A (n = 50) was given a contrast medium (CM) dose of 0.5 mL/kg at 80 kV while group B (n = 50) was given a CM dose of 1 mL/kg at 100 kV. Bolus tracking technique was used. Attenuation values were measured from the center of different pulmonary arterial segments. Values over 350 Hounsfield unit (HU) were accepted as significant. Image qualities of all pulmonary arterial segments were sufficient for diagnosis. The mean and effective doses of radiation received by patients in the two groups were compared. Results: PTE was detected in twenty-one patients (21%) in both groups. Total mean attenuation values for pulmonary arteries were significantly higher in group A than in group B (532.7±243 HUvs. 380.6±232 HU respectively, P < 0.001). Total dose length product (DLP) (76.5±17.3 mGy.cm vs. 162.1±31.3 mGy.cm, P < 0.001) and effective dose values (1.2±0.2 mSv vs. 2.4±0.2 mSv, P < 0.001) were significantly lower in group A compared to group B. Conclusion: CTPA maybe obtained using an imaging protocol with low kV and reduced volume of contrast medium in the diagnosis of PTE. [ABSTRACT FROM AUTHOR]

Objective To evaluate the clinical value of low kVp with iterative reconstruction in multislice spiral computed tomography of lumber vertebrae in young soldiers. Methods Sixty young soldiers who suffered from lumbar diseases were randomly divided into a control group (120 kVp) and a test group (100 kVp), who underwent CT examination with 120 kVp tube voltage in the control group and 100 kVp tube voltage in the test group. The control group went through filtered back projection (FBP) for image reconstruction. The test group applied FBP or sinogram-affirmed iterative reconstruction (SAFIRE) based on image reconstruction requirements, and then were divided into FBP test group and SAFIRE test group. The noise and SNR (signal to noise ratio) of the images were measured in each group. Meanwhile two experienced radiologists evaluated the quality of images. CT DIvol, DLP and ED were used to measure the scan dose in each group. Mean tube current was recorded by CARE Dose 4D. The data were analyzed with SPSS. Results There were no significant difference between the objective and subjective image evaluations in SAFIRE test group and the control group (P>0.05), while there were statistical differences between FBP test group and the control group or between the two test groups (P<0.05). The radiation doses in the test groups were both lower significantly than that in the control group, and the ED values in the test groups were decreased by 43% when compared with the control group. The test groups had the tube voltages not obviously different from that in the control group (P >0.05). Conclusion The radiation dose in the lumbar multislice spiral CT examination of young soldiers is decreased significantly when the tube voltage falls to 100 kVp, the same image quality as that by conventional 120 kVp tube voltage can be obtained by combining iterative reconstruction. [ABSTRACT FROM AUTHOR]

To compare the radiation dose and image noise of nonenhanced CT scans performed at 80, 100, and 120 kVp with tube current modulation ( TCM) we used anthropomorphic phantoms of newborn, 1-year-old, and 5-year-old children. The noise index was set at 12. The image noise in the center of the phantoms at the level of the chest and abdomen was measured within a circumscribed region of interest. We measured the doses in individual tissues or organs with radio-photoluminescence glass dosimeters for each phantom. Various tissues or organs were assigned and the radiation dose was calculated based on the international commission on radiological protection definition. With TCM the respective radiation dose at tube voltages of 80, 100, and 120 was 29.71, 31.60, and 33.79 mGy for the newborn, 32.00, 36.79, and 39.48 mGy for the 1-year-old, and 32.78, 38.11, and 40.85 mGy for the 5-year-old phantom. There were no significant differences in the radiation dose among the tube voltages and phantoms ( P > 0.05). Our comparison of the radiation dose using anthropomorphic phantoms of young children showed that the radiation dose of nonenhanced CT performed at different tube voltages with TCM was not significantly different. [ABSTRACT FROM AUTHOR]

Purpose: The aims of this study were twofold. First, we investigated the extent of changes in arterial peak enhancement and changes in the duration of a diagnostic arterial enhancement when small amounts of CA volumes (≤30mL) were administered at varying tube voltages. Second, we investigated how to optimize CA injection protocols for CT-angiography with long scan times at various tube voltages to achieve optimal vascular enhancement at the lowest reasonable CA dose.Materials and Methods: Measurements were performed with a custom-made dynamic flow phantom. For CTA protocols with a short scan time, we investigated the effect of various tube voltages (70-120kVp) on the arterial enhancement profile with very small CA volumes (20 and 30mL of Iobitridol 350mg I/mL) at a flow rate of 5mL/s. For CTA protocols with a long scan time, we utilized an optimized multi-bolus technique switching rapidly between 13 "micro-boli" of CA (total, 60mL) and saline (total, 24mL) at a flow rate of 4mL/s. The peak arterial enhancement (PAE) and the time period of diagnostic aortic enhancement ≥200 HU (T200) were analyzed.Results: For the short scan time protocols, a diagnostic peak enhancement was achieved using 20mL of CA at 70 and 80kVp (PAE: 327±10 and 255±15 HU, respectively) or 30mL of CA at 70, 80 and 100kVp (PAE 451±10, 367±9, and 253±15 HU). For the long scan time, the optimized multi-bolus injection protocol extended T200 at 100kVp by 6s (40%) compared to a linear injection protocol (21±1s and 15±1s, respectively; p<0.001).Conclusion: Optimized CTA protocols comprising alternations of tube voltage and the CA injection protocol can save radiation doses and CA volumes at the same time. [ABSTRACT FROM AUTHOR]

Abstract: To compare the noise reduction and image quality of different iDosc construction grade in low tube voltage computed tomography angiography (CTA) in head and neck artery angiography, 30 patients underwent head and neck CTA with 50mL 300mgI/ML contrast media at lOOkV tube voltage were selected. All the images were reconstructed from iDosc-1 to iDosc-6. The CT values of the left middle cerebral artery (Ml), left temporal lobe, standard deviation (SD) were recorded. The contrast to noise ratio (CNR) and signal-to-noisc ratio (SNR) were calculated. The results showed that there were no significant statistic differences (P>0.05) in subjectively evaluating image quality of CTA in head and neck artery angiography among the construction from iDosc-1 to iDosc-6, and the score of image quality was the highest in iDosc-4 grade construction. Moreover, there were no significant statistic differences (P>0.05) in the CT value of left middle cerebral artery (Ml) and the left temporal lobe. Besides, the value of SD was reduced with the increase of iDosc grade, while the values of SNR and CNR were on the contrary. The SD value of the iDosc-5 reconstruction reached the lowest and the SNR and CNR values reached the highest, and the quality of image were the best. It is concluded that iDosc can reduce the noise effectively and improve the quality of image in the head and neck artery angiography at low tube voltage, and the image quality of iDosc-5 were the best. [ABSTRACT FROM AUTHOR]

Purpose: To investigate image quality, radiation dose, and diagnostic efficiency of prospectively ECG-triggered high-pitch coronary CT angiography (CCTA) at 70 kVp with 30mL contrast agent intra-individually compared with routine CCTA protocol.Materials and Methods: One hundred and thirty eight patients with suspected coronary artery disease, body mass index (BMI)≤25kg/m2 and heart rate (HR)≤70 beats per minute (bpm) underwent prospectively ECG-triggered high-pitch CCTA at 70 kVp and 30mL contrast agent (protocol A) and prospectively ECG-triggered sequential scanning at 120 kVp and 60mL contrast medium (protocol B). Objective and subjective image quality, radiation doses, and diagnostic accuracy were evaluated and compared between the two protocols.Results: Higher CT attenuation, higher noise, lower signal-to-noise ratios (SNRs) and lower contrast-to-noise ratios (CNRs) were found in protocol A than in protocol B (P<0.001). However, image quality of protocol A were diagnostic. In patients with BMI<23kg/m2 or HR<60bpm, subjective image quality scores of some coronary arteries in protocol A were not significantly different from protocol B (P>0.05). Effective dose in protocol A has reduced by 96.7% compared with protocol B (P<0.001). No significant differences were found for diagnostic accuracy between the two protocols on a per-segment (P=0.513), per-vessel (P=0.317) and per-patient (P=0.125) basis.Conclusions: Prospectively ECG-triggered high-pitch CCTA at 70kVp with 30mL contrast agent can reduce radiation dose but maintain image quality and high diagnostic accuracy in a selected, non-obese population. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the radiation dose and image quality of cerebral CT angiography (CTA) at 70kVp with 30mL iodinated contrast agent.Methods: One hundred patients were prospectively classified into two groups: Group A (n=50), 120kVp cerebral CTA with 60mL iodinated contrast agent reconstructed by filtered back projection (FBP) and Group B (n=50), 70kVp with 30mL iodinated contrast agent reconstructed by sinogram-affirmed iterative reconstruction (SAFIRE). CT values, noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the internal carotid artery (ICA) and middle cerebral artery (MCA) were measured. Subjective image quality was evaluated. Effective dose (ED) was calculated.Results: The mean CT values of the ICA and MCA of Group B were higher than those of Group A (all P<0.001). The mean noise of Group A was lower than that of Group B (P<0.001). SNRICA, SNRMCA and CNRICA, CNRMCA of Group A were higher than Group B (all P<0.001). There was no difference in vessel sharpness, noise, and overall quality between the two groups (all P>0.05). ED of Group B (0.2±0.0mSv) was lower than Group A (1.3±0.1 mSv) (p<0.001).Conclusion: Cerebral CTA with iterative reconstruction at 70kVp and 30mL iodinated contrast agent is feasible, allowing for substantial dose reduction compared with conventional cerebral CTA protocol. [ABSTRACT FROM AUTHOR]

Background: GE Healthcare's new generation of deep-learning image reconstruction (DLIR), the Revolution Apex CT is the first CT image reconstruction engine based on a deep neural network to be approved by the US Food and Drug Administration (FDA). It can generate high-quality CT images that restore the true texture with a low radiation dose. The aim of the present study was to assess the image quality of coronary CT angiography (CCTA) at 70 kVp with the DLIR algorithm as compared to the adaptive statistical iterative reconstruction-Veo (ASiR-V) algorithm in patients of different weight., Methods: The study group comprised 96 patients who underwent CCTA examination at 70 kVp and were subdivided by body mass index (BMI) into normal-weight patients [48] and overweight patients [48]. ASiR-V40%, ASiR-V80%, DLIR-low, DLIR-medium, and DLIR-high images were obtained. The objective image quality, radiation dose, and subjective score of the two groups of images with different reconstruction algorithms were compared and statistically analyzed., Results: In the overweight group, the noise of the DLIR image was lower than that of the routinely used ASiR-40%, and the contrast-to-noise ratio (CNR) of DLIR (H: 19.15±4.31; M: 12.68±2.91; L: 10.59±2.32) was higher than that of the ASiR-40% reconstructed image (8.39±1.46), with statistically significant differences (all P values <0.05). The subjective image quality evaluation of DLIR was significantly higher than that of ASiR-V reconstructed images (all P values <0.05), with the DLIR-H being the best. In a comparison of the normal-weight and overweight groups, the objective score of the ASiR-V-reconstructed image increased with increasing strength, but the subjective image evaluation decreased, and both differences (i.e., objective and subjective) were statistically significant (P<0.05). In general, the objective score of the DLIR reconstruction image between the two groups increased with increased noise reduction, and the DLIR-L image was the best. The difference between the two groups was statistically significant (P<0.05), but there was no significant difference in subjective image evaluation between the two groups. The effective dose (ED) of the normal-weight group and the overweight group was 1.36±0.42 and 1.59±0.46 mSv, respectively, and was significantly higher in the overweight group (P<0.05)., Conclusions: As the strength of the ASiR-V reconstruction algorithm increased, the objective image quality increased accordingly, but the high-strength ASiR-V changed the noise texture of the image, resulting in a decrease in the subjective score, which affected disease diagnosis. Compared with the ASiR-V reconstruction algorithm, the DLIR reconstruction algorithm improved the image quality and diagnostic reliability for CCTA in patients with different weights, especially in heavier patients., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-22-1141/coif). XS and YS are employees of GE (China) CT Imaging Research Center. The other authors have no conflicts of interest to declare., (2023 Quantitative Imaging in Medicine and Surgery. All rights reserved.)

Purpose: To evaluate image quality and diagnostic accuracy for acute infarct detection and radiation dose of 70 kVp whole brain CT perfusion (CTP) and CT angiography (CTA) reconstructed from CTP source data.Methods: Patients were divided into three groups (n = 50 each): group A, 80 kVp, 21 scanning time points; groups B, 70 kVp, 21 scanning time points; group C, 70 kVp, 17 scanning time points. Objective and subjective image quality of CTP and CTA were compared. Diagnostic accuracy for detecting acute infarct and cerebral artery stenosis ≥ 50 % was calculated for CTP and CTA with diffusion weighted imaging and digital subtraction angiography as reference standards. Effective radiation dose was compared.Results: There were no differences in any perfusion parameter value between three groups (P > 0.05). No difference was found in subjective image quality between three groups (P > 0.05). Diagnostic accuracy for detecting acute infarct and vascular stenosis showed no difference between three groups (P > 0.05). Compared with group A, radiation doses of groups B and C were decreased by 28 % and 37 % (both P < 0.001), respectively.Conclusion: Compared with 80 kVp protocol, 70 kVp brain CTP allows comparable vascular and perfusion assessment and lower radiation dose while maintaining high diagnostic accuracy in detecting acute infarct.Key Points: • 70 kVp whole brain CTP can provide diagnostic image quality. • 70 kVp CTP diagnostic accuracy was maintained vs. 80 kVp protocol. • 70 kVp CTP radiation doses were lower than 80 kVp protocol. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: The study aimed to compare image quality of filtered back projection (FBP) and iterative reconstruction (advanced modeled iterative reconstruction, ADMIRE) in contrast-enhanced computed tomography (CT) of the abdomen, and to assess the differences of reconstructions according to these methods. It also aimed to investigate the potential for noise reduction of ADMIRE for different reconstructed slice thicknesses.Materials and Methods: CT data of the abdomen and pelvis were acquired using a 128-slice single-source CT system using automated kV selection and tube current adaption based on patients' anatomy. Raw data sets from patients scanned at 100 kV were selected, and images were reconstructed with slice thicknesses of 1 mm, 3 mm, and 5 mm, both with FBP and ADMIRE. Filter strength F1, F3, and F5 of the ADMIRE algorithm and the corresponding reconstruction kernels were used. In total, 58 raw data sets from 17 patients were used to reconstruct from the same raw data FBP and ADMIRE images, representing identical body regions. Identical regions of interest were placed at the same position of up to four images and image noise was measured. Differences of reconstructed images and detail preservation were tested using an image subtraction technique, and subjective image quality was assessed using a 5-point Likert scale.Results: On average, for 1-mm slice thickness, noise reduction was 9.15% ± 2.4% with filter strength level F1, 30.2% ± 3.4% with F3, and 54.4% ± 7.0% with F5 as compared to FBP. For a slice thickness of 3 mm, noise reduction was 8.5% ± 3.7% with F1, 28.6% ± 3.9% with F3, and 52.2% ± 9.1% with F5. For 5 mm, the corresponding values are 8.9% ± 2.7%, 31.4% ± 2.8%, and 52.7% ± 7.7%. On subtraction images, edge information of tissue classes with a high attenuation gradient was found, but structures with small differences in attenuation were not detectable on subtraction images, confirming that no relevant details were lost in the iterative reconstruction process.Conclusions: ADMIRE is able to reduce image noise considerably (up to 50%) without any obvious negative impact on lesion depiction as assessed visually. Noise reduction of ADMIRE seems to be independent of slice thickness. [ABSTRACT FROM AUTHOR]

Background: Low kilovoltage (kVp) computed tomography (CT) may be used to reduce contrast medium dose in patients at risk of contrast nephropathy, at the cost of increased image noise.Purpose: To evaluate: (i) the impact of iterative reconstructions (Siemens SAFIRE) on low-contrast object detection to compensate for increased noise instead of increased tube loading when decreasing tube potential; and (ii) the change in iodine attenuation in simulated abdominal CT.Material and Methods: A phantom was scanned at 70, 80, 100, and 120 kVp at fixed effective tube loading (170 mAsEFF) and fixed radiation dose (CTDIVOL 10 mGy). Images were reconstructed with filtered back-projection (FBP) and SAFIRE strengths S1-S5. Iodine attenuation, objective image noise, contrast-to-noise ratio (CNR), noise power spectrum (NPS), spatial resolution, and subjective detectability of low-contrast objects were evaluated.Results: Compared with 120 kVp iodine attenuation increased by a factor 1.6 and 2.0, and image noise increased by a factor 1.9 and 2.5 at 80 and 70 kVp, respectively. Compared with FBP, SAFIRE showed objective reduction in image noise and increased CNR without loss of spatial resolution or any significant NPS alteration, with general tendency to improve subjective detectability of low-contrast objects. At 170 mAsEFF the number of discernible 1.0% contrast objects at 70 kVp/S5 and 80 kVp/S5 was similar to that at 120 kVp/FBP.Conclusion: With the SAFIRE algorithm image noise, CNR and detectability of low-contrast objects may be kept unchanged without increased tube loading when using low kVp settings to reduce contrast medium dose in azotemic patients. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: The purpose of this study was to assess the effect of a low-tube-voltage technique and iterative reconstruction (IR) on the radiation dose and image quality of computed tomography colonography (CTC). Materials and Methods: We studied 30 patients (14 women and 16 men; mean age, 64.5 ± 13.1 years; range, 39-90 years) with colorectal cancer referred for surgical treatment. All underwent CTC with fecal tagging under a standard 120-kVp protocol in the supine position and a 100-kVp protocol in the prone position. The 120-kVp images were reconstructed with filtered back projection (FBP). The 100-kVp images were postprocessed using FBP and a hybrid type of IR (adaptive iterative dose reduction 3D). The effective radiation dose (ED), image noise, and contrast-to-noise ratio (CNR) were compared among the three protocols. The visual image quality was scored on a four-point scale. Results: The mean ED was significantly lower under the 100-kVp protocol than the 120-kVp protocol, resulting in a 27% radiation dose decrease (3.5 ± 2.0 vs 2.5 ± 1.5 mSv; P < .01). Image noise decreased by 48%, and the mean attenuation of tagged fluid increased from 452 to 558 HU on images acquired at 100 kVp with IR compared to that in the 120-kVp protocol; these differences were significant. The mean CNR was significantly higher under the 100 kVp with IR than the other two protocols. We found no significant differences in the visual scores for diagnostic utility between the 100 kVp with IR and the 120 kVp with FBP protocol (P = .10). Conclusions: Low-tube-voltage CTC reduced the radiation dose by approximately 27% while maintaining the image quality. [ABSTRACT FROM AUTHOR]

Purpose We used pediatric and adult anthropomorphic phantoms to compare the radiation dose of low- and standard tube voltage chest and abdominal non-contrast-enhanced computed tomography (CT) scans. We also discuss the optimal low tube voltage for non-contrast-enhanced CT. Methods Using a female adult- and three differently-sized pediatric anthropomorphic phantoms we acquired chest and abdominal non-contrast-enhanced scans on a 320-multidetector CT volume scanner. The tube voltage was set at 80-, 100-, and 120 kVp. The tube current was automatically assigned on the CT scanner in response to the set image noise level. On each phantom and at each tube voltage we measured the surface and center dose using high-sensitivity metal-oxide-semiconductor field-effect transistor detectors. Results The mean surface dose of chest and abdominal CT scans in 5-year olds was 4.4 and 5.3 mGy at 80 kVp, 4.5 and 5.4 mGy at 100 kV, and 4.0 and 5.0 mGy at 120 kVp, respectively. These values were similar in our 3-pediatric phantoms (p > 0.05). The mean surface dose in the adult phantom increased from 14.7 to 19.4 mGy for chest- and from 18.7 to 24.8 mGy for abdominal CT as the tube voltage decreased from 120 to 80 kVp (p < 0.01). Conclusion Compared to adults, the surface and center dose for pediatric patients is almost the same despite a decrease in the tube voltage and the low tube voltage technique can be used for non-contrast-enhanced chest- and abdominal scanning. [ABSTRACT FROM AUTHOR]

We evaluated the feasibility of sub-millisievert (mSv) coronary CT angiography (CCTA) using low tube voltage, prospective ECG gating, and a knowledge-based iterative model reconstruction algorithm. Twenty-four non-obese healthy subjects (M:F 13:11; mean age 50.2 ± 7.8 years) were enrolled. Three sets of CT images were reconstructed using three different reconstruction methods: filtered back projection (FBP), iterative reconstruction (IR), and knowledge-based iterative model reconstruction (IMR). The scanning parameters were as follows: step-and-shoot axial scanning, 80 kVp, and 200 mAs. On the three sets of CT images, the attenuation and image noise values were measured at the aortic root. The signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) were calculated at the proximal right coronary artery and the left main coronary artery. The qualitative image quality of the CCTA with IMR was assessed using a 4-point grading scale (grade 1, poor; grade 4, excellent). The mean radiation dose of the CCTA was 0.89 ± 0.09 mSv. The attenuation values with IMR were not different from those of other reconstruction methods. The image noise with IMR was significantly lower than with IR and FBP. Compared to FBP, the noise reduction rate of IMR was 69 %. The SNR and CNR of CCTA with IMR were significantly higher than with FBP or IR. On the qualitative analysis with IMR, all included segments were diagnostic (grades 2, 3, and 4), and the mean image quality score was 3.6 ± 0.6. In conclusion, CCTA with low tube voltage, prospective ECG gating, and an IMR algorithm might be a feasible method that allows for sub-millisievert radiation doses and good image quality when used with non-obese subjects. [ABSTRACT FROM AUTHOR]

Introduction: To investigate low-tube-voltage 80-kVp computed tomography (CT) of head and neck primary and recurrent squamous cell carcinoma (SCC) regarding objective and subjective image quality. Methods: We retrospectively evaluated 65 patients (47 male, 18 female; mean age: 62.1 years) who underwent head and neck dual-energy CT (DECT) due to biopsy-proven primary ( n = 50) or recurrent ( n = 15) SCC. Eighty peak kilovoltage and standard blended 120-kVp images were compared. Attenuation and noise of malignancy and various soft tissue structures were measured. Tumor signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was rated by three reviewers using 5-point grading scales regarding overall image quality, lesion delineation, image sharpness, and image noise. Radiation dose was assessed as CT dose index volume (CTDI). Interobserver agreement was calculated using intraclass correlation coefficient (ICC). Results: Mean tumor attenuation (153.8 Hounsfield unit (HU) vs. 97.1 HU), SNR (10.7 vs. 8.3), CNR (8.1 vs. 4.8), and subjective tumor delineation (score, 4.46 vs. 4.13) were significantly increased (all P < 0.001) with 80-kVp acquisition compared to standard blended 120-kVp images. Noise of all measured structures was increased in 80-kVp acquisition ( P < 0.001). Overall interobserver agreement was good (ICC, 0.86; 95 % confidence intervals: 0.82-0.89). CTDI was reduced by 48.7 % with 80-kVp acquisition compared to standard DECT (4.85 ± 0.51 vs. 9.94 ± 0.81 mGy cm, P < 0.001). Conclusions: Head and neck CT with low-tube-voltage 80-kVp acquisition provides increased tumor delineation, SNR, and CNR for CT imaging of primary and recurrent SCC compared to standard 120-kVp acquisition with an accompanying significant reduction of radiation exposure. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate radiation dose, image quality, and optimal level of sinogram-affirmed iterative reconstruction (SAFIRE) of cerebral CT angiography (CTA) at 70 kVp. Methods: One hundred patients were prospectively classified into two groups: Group A (n = 50), 70 kVp cerebral CTA with 5 levels of SAFIRE reconstruction (S1-S5); and Group B (n = 50), 120 kVp with filtered back projection (FBP) reconstruction. CT attenuation values, noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the internal carotid artery (ICA) and middle cerebral artery (MCA) were measured. Subjective image quality was evaluated. Effective dose (ED) was estimated. Results: CT attenuation and noise of the ICA and MCA in Group A were higher than those of Group B (all P < 0.001) while the SNR, SNR, CNR, and CNR of Group A at S4-5 were comparable to ( P > 0.05) or higher than in Group B ( P < 0.05). There was no difference in overall image quality between Group A S3-5 and Group B ( P > 0.05). ED was 0.2 ± 0.0 mSv for Group A with 85 % ED reduction in comparison to Group B (1.3 ± 0.2 mSv). Conclusion: Cerebral CTA at 70 kVp is feasible, allowing for substantial radiation dose reduction. SAFIRE S4 level is recommended for obtaining optimal image quality. Key points: • 70 kVp cerebral CTA is feasible and provides diagnostic image quality. • 70 kVp cerebral CTA resulted in 85 % effective dose reduction. • S4 level of SAFIRE is recommended for 70 kVp cerebral CTA. [ABSTRACT FROM AUTHOR]

Background Among CT scanners, 320-row instruments feature decreased photon energy and yield strong contrast enhancement. Consequently, the contrast medium (CM) dose can be reduced. The results of low-tube-voltage coronary CT angiography (CCTA) performed on 320-row scanners have not been adequately assessed. Objective We evaluated the effects of a low-contrast-dose protocol on the image quality of CCTA using 80 kVp tube voltage, iterative reconstruction (IR), and a 320-row scanner. Methods We randomly assigned 90 patients (mean body weight, 56.5 ± 11.0 kg) to 1 of 3 CCTA protocols. Under protocol A, 30 were scanned using a conventional 120-kVp protocol and a standard CM dose (280 mg iodine/kg body weight [mgI/kg]). Another 30 underwent scanning at 80 kVp with a 25% CM dose reduction (210 mgI/kg; protocol B). Under protocol C, the remaining 30 patients were scanned at 80 kVp with a 50% CM dose reduction (140 mgI/kg). The 120 and 80 kVp images were processed with IR. Images obtained under the 3 protocols were subjected to quantitative and qualitative analysis. Results The amount of CM used in protocol A, B, and C was 43.6 ± 10.1, 30.3 ± 4.4, and 21.0 ± 4.0 mL, respectively. Mean CT attenuation of the coronary arteries tended to be higher under protocol B than the other 2 protocols. The contrast-to-noise ratio was significantly higher under protocol B. The mean visual scores were significantly higher for protocols A and B than protocol C. The mean effective radiation dose was significantly lower under the 80-kVp protocol. Conclusion With a 320-row scanner and our refined CM injection and timing protocol, it is technically feasible to obtain sufficient vascular enhancement with a reduction in the CM and/or radiation dose at 80-kVp CCTA with IR. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the image quality, radiation dose and diagnostic accuracy of 80kVp, high-pitch CT pulmonary angiography (CTPA) with iterative reconstruction using 20 ml of contrast agent. Methods: One hundred patients with suspected pulmonary embolism (PE) were randomly divided into two groups ( n = 50 each; group A, 100 kVp, 1.2 pitch, 60 ml of contrast medium and filtered back projection algorithm; group B, 80 kVp, 2.2 pitch, 20 ml of contrast medium and sinogram affirmed iterative reconstruction). Image quality, diagnostic accuracy and radiation dose were evaluated and compared. Results: Mean CT numbers of pulmonary arteries in group B were higher than those in group A (all P < 0.001). Contrast-to-noise ratio and signal-to-noise ratio of group B were higher than those of group A (both P < 0.001). There was no significant difference in subjective image quality scores between two groups ( P = 0.807). The interobserver agreement was excellent (k = 0.836). There was no significant difference in diagnostic accuracy between the two groups ( P > 0.05). Compared with group A, radiation dose of group B was reduced by 50.3 % ( P < 0.001). Conclusions: High-pitch CTPA at 80 kVp can obtain sufficient image quality in normal-weight individuals with 20 ml of contrast agent and half the radiation dose of a conventional CTPA protocol. Key Points: • CTPA is feasible at 80 kVp using only 20 ml of contrast agent. • High-pitch CTPA at 80 kVp has an effective dose under 1 mSv. • This CTPA protocol can obtain sufficient image quality in normal-weight individuals. [ABSTRACT FROM AUTHOR]

Objectives To determine the impact of hybrid iterative reconstruction (HIR) on image quality in 80 kV CT pulmonary angiography (CTPA) in comparison to filtered-back-projection (FBP). Methods Fifty patients (body weight <80 kg) with suspected pulmonary embolism (PE) underwent CTPA at 80 kV (mean CTDIvol, 2.3 mGy; effective dose, 1.2 mSv). The raw data were reconstructed using FBP and three increasing HIR levels. Two radiologists assessed image quality and image noise. Conspicuity of PE was assessed in central, segmental, and subsegmental arteries. CT attenuation of pulmonary arteries, objective image noise (OIN) and contrast-to-noise ratios (CNR) were assessed. Results With each HIR level, a significant decrease in subjective and objective image noise was achieved with a reduction of OIN up to 46% in comparison with FBP. CNR significantly increased with the application of HIR compared to FBP. Image quality was rated significantly higher at HIR reconstructions in comparison with FBP. Diagnosis of PE was feasible with each data set; however, conspicuity of central and segmental PE significantly improved with the use of HIR. Conclusions Eighty kilovoltage CTPA with HIR provides improved image quality and conspicuity of pulmonary embolism enabling low dose CTPA protocols close to 1 mSv in patients weighing less than 80 kg. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the effects of a new model-based type of iterative reconstruction (M-IR) technique, the iterative model reconstruction, on image quality of prospectively gated coronary CT angiography (CTA) acquired at low-tube-voltage. Methods: Thirty patients (16 men, 14 women; mean age 52.2±13.2 years) underwent coronary CTA at 100-kVp on a 256-slice CT. Paired image sets were created using 3 types of reconstruction, i.e. filtered back projection (FBP), a hybrid type of iterative reconstruction (H-IR), and M-IR. Quantitative parameters including CT-attenuation, image noise, and contrast-to-noise ratio (CNR) were measured. The visual image quality, i.e. graininess, beam-hardening, vessel sharpness, and overall image quality, was scored on a 5-point scale. Lastly, coronary artery segments were evaluated using a 4-point scale to investigate the assessability of each segment. Results: There was no significant difference in coronary arterial CT attenuation among the 3 reconstruction methods. The mean image noise of FBP, H-IR, and M-IR images was 29.3±9.6, 19.3±6.9, and 12.9±3.3HU, respectively, there were significant differences for all comparison combinations among the 3 methods (p <0.01). The CNR of M-IR was significantly better than of FBP and H-IR images (13.5±5.0 [FBP], 20.9±8.9 [H-IR] and 39.3±13.9 [M-IR]; p <0.01). The visual scores were significantly higher for M-IR than the other images (p <0.01), and 95.3% of the coronary segments imaged with M-IR were of assessable quality compared with 76.7% of FBP- and 86.9% of H-IR images. Conclusions: M-IR can provide significantly improved qualitative and quantitative image quality in prospectively gated coronary CTA using a low-tube-voltage. [ABSTRACT FROM AUTHOR]