Application of 70 kVp in abdominal CT angiography to reduce both radiation and contrast dosage and improve patient comfort for children

BACKGROUND: Low-tube voltage scanning improves CT attenuation value of contrast medium (CM). Thus, we hypothesized that 70 kVp in pediatric abdominal CT angiography (CTA) could be used to reduce both radiation and CM dose and improve patient comfort at the same time. OBJECTIVE: To evaluate the feasibility of using 70 kVp in pediatric abdominal CTA to reduce radiation dose and CM dose and improve patient care for children. MATERIALS AND METHODS: Forty-six children needing abdominal CTA were enrolled in the study group using low-dose scanning protocol with 70 kVp and 0.7–1.1 ml/kg contrast dose, and reconstructed with 50%ASIR-V. They were compared with other 46 children in control group with matching body weight and underwent conventional CT scans with 100 kVp, 1.2–1.8 ml/kg contrast dose and reconstructed using 50%ASIR. Image quality of large vessels was evaluated using a 5-point scale. CT value and standard deviation of descending aorta (Ao) was measured, and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Radiation dose, contrast dose, the maximum injection pressure between the two groups were also compared. RESULTS: Score for displaying large vessels by 70 kVp images was 3.91±0.28, lower than that (4.17±0.38) of the control group (p < 0.05), but fully met the diagnostic requirements. CT value of Ao was 390.87±86.79HU in study group, which is higher than 343.93±49.94HU in control group, while there was no difference in SNR and CNR between two groups; the radiation dose, contrast dosage and injection pressure of the study group were 1.23±0.39mGy, 12.67±7.27 ml and 43.83±17.16psi, respectively, which are significantly lower than the 1.95±0.37mGy, 22.67±7.39 ml, and 77.59±19.68psi of control group. CONCLUSION: Use of 70 kVp in pediatric abdominal CTA provides diagnostic quality images while significantly reduce radiation and contrast dose, as well as injection pressure to improve patient comfort for children.

Application of 70kVp in abdominal CT angiography to reduce both radiation and contrast dosage and improve patient comfort for children

Objective To evaluate the application of 70kVp in pediatric abdominal CT angiography (CTA) to reduce radiation and contrast dose and improve patient comfort. Methods Forty-six children needing abdominal CTA were enrolled in the study group using low-dose scanning protocol with 70kVp and 0.7-1.1ml/kg contrast dose, and reconstructed with 50%ASIR-V. They were compared with another 46 children (control group) with matching body weight who underwent conventional CT scans with 100kVp, 1.2-1.8ml/kg contrast dose and reconstructed using 50%ASIR. The image quality of large vessels was evaluated using a 5-point scale, and the number of superior mesenteric artery branches identifiable by CAD was recorded. The CT value and standard deviation of descending aorta (Ao) was measured, and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) calculated. Radiation dose, contrast dose, the maximum injection pressure, correlation between flow rate and injection pressure were compared between the two groups. Results The score for displaying large vessels by 70kVp images was 3.91±0.28, and up to 3 superior mesenteric artery branches could be identified, all of which met the diagnostic requirements. The CT value of Ao was 390.87±86.79HU in the study group, higher than 343.93±49.94HU in the control group, while no difference in SNR and CNR between the two groups; the radiation dose, contrast dosage and injection pressure of the study group were 1.23±0.39mGy, 12.67±7.27ml and 43.83±17.16psi respectively, significantly lower than the 1.95±0.37mGy, 22.67±7.39ml, and 77.59±19.68psi of the control group. The correlation coefficients between flow rate and injection pressure were 0.82 and 0.86 in 70kVp group and 100kVp group. Conclusion 70kVp scanning meets the diagnostic requirements in pediatric abdominal CTA while providing significant radiation dose, contrast dose and injection pressure reduction.

Optimal Monochromatic Energy Levels in Dual-Energy Spectral CT Pulmonary Angiography with Low Contrast Medium Dosage

Background: The contrast medium (CM) in CT pulmonary angiography may induce adverse effects to patients, and higher CM is associated with higher rates of contrast-induced-nephropathy and mortality. Reduction of CM dosage through improvement of examination techniques may help reduce the occurrence of CM-induced adverse effects and healthcare costs. Objectives: To determine the optimal monochromatic energy levels in dual-energy spectral CT pulmonary angiography (CTPA) with low contrast dosage. Patients and Methods: Thirty patients with suspected pulmonary embolism (PE) underwent dual-energy spectral CTPA with low radiation and low contrast doses with scanning protocol of GSI-36 with 260 mA, and 25 mL contrast (350 mgI/mL) with 4.0ml/s injection speed. The monochromatic images from 60 - 80 keV (interval 5 keV) were reconstructed using a 50% adaptive statistical iterative reconstruction (50% ASiR) algorithm at 1.25 mm slice thickness. The CT attenuation and standard deviation (SD) values of the main, right, left, right lower and left lower pulmonary arteries and the back muscle at the same level were measured on 60 – 80 keV images, and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated and analyzed. The subjective image quality was evaluated by two experienced radiologists using a 5-level scoring method independently. Measurements were analyzed using IBM SPSS Statistics for Windows, version 25.0. (Armonk, NY: IBM Corp.). Results: CT attenuation values of the pulmonary arteries decreased with the increase of energy level in five-energy groups, with values greater than 300 HU at 60 keV - 70 keV energies. The 65 keV image had the highest SNR, CNR and lowest SD, with significant differences compared with those of other image sets (P < 0.05). The subjective quality scores for the 65 keV image was judged to be the highest by the two radiologists, but it was not significantly different from 60 keV and 70 keV (all P > 0.05). Conclusion: The 65 keV monochromatic images provided the highest SNR, CNR and subjective scores with the lowest image noise in dual-energy spectral CTPA with low contrast dosage.