Iodine load reduction in dual-energy spectral CT portal venography with low energy images combined with adaptive statistical iterative reconstruction

Objective: To study the application of using low energy images combined with adaptive statistical iterative reconstruction (ASiR) in dual-energy spectral CT portal venography (CTPV) to reduce iodine load. Methods: 41 patients for CTPV were prospectively and randomly divided into two groups. Group A ( n = 21) used conventional 120 kVp scanning protocol with contrast dose at 0.6 gI/kg while group B ( n = 20) used dual-energy spectral imaging with reduced contrast dose at 0.3 gI/kg. The 120 kVp images in Group A and 50 keV images in Group B were reconstructed with 40% ASiR. The contrast-to-noise ratio of portal vein was calculated. The image quality and the numbers of intrahepatic portal vein branches were evaluated by two experienced radiologists using a 5-point scoring system. Results: Group B reduced iodine load by 52% compared to Group A (17.21 ± 3.30 gI vs 35.80 ± 6.18 gI, p < 0.001). All images in both groups were acceptable for diagnosis. CT values and standard deviations in portal veins of Group B were higher than Group A (all p < 0.05); There were no statistical differences in contrast-to-noise ratio, image quality score and the number of observed portal vein branches between the two groups (all p > 0.05), and the two observers had excellent agreement in image quality assessment (all κ > 0.75). Conclusion: The use of 50 keV images in dual-energy spectral CTPV with ASiR reduces total iodine load by 52% while maintaining good image quality. Advances in knowledge: Spectral CT images combined with ASiR can be used in low contrast dose CTPV portal venography to maintain image quality and reduce contrast dose.

Download Full-text

Reducing contrast medium dose with low photon energy images in renal dual-energy spectral CT angiography and adaptive statistical iterative reconstruction (ASIR)

British Journal of Radiology ◽

10.1259/bjr.20200974 ◽

2021 ◽

pp. 20200974

Author(s):

Xirong Zhang ◽

Jing Chen ◽

Nan Yu ◽

Zhanli Ren ◽

Qian Tian ◽

...

Keyword(s):

Renal Artery ◽

Contrast Medium ◽

Iterative Reconstruction ◽

Dual Energy ◽

Spectral Ct ◽

Adaptive Statistical Iterative Reconstruction ◽

Statistical Iterative Reconstruction ◽

Group A ◽

Group B ◽

Medium Dose

Objective: To evaluate the value of using low energy (keV) images in renal dual-energy spectral CT angiography (CTA) and adaptive statistical iterative reconstruction (ASIR) to reduce contrast medium dose. Methods: 40 patients with renal CTA on a Discovery CT750HD were randomly divided into two groups: 20 cases (Group A) with 600 mgI kg−1 and 20 cases (Group B) with 300 mgI kg−1. The scan protocol for both groups was: dual-energy mode with mA selection for noise index of 10 HU, pitch 1.375:1, rotating speed 0.6 s/r. Images were reconstructed at 0.625 mm thickness with 40%ASIR, Group A used the conventional 70keV monochromatic images, and Group B used monochromatic images from 40 to 70 keV at 5 keV interval for analysis. The CT values and standard deviation (SD) values of the renal artery and erector spine in the plain and arterial phases were measured with the erector spine SD value representing image noise. The enhancement degree of the renal artery (ΔCT = CT(arterial) -CT(plain)), signal-to-noise ratio (SNR=CTrenal-artery/SDrenal-artery) and contrast-to-noise ratio (CNR=(CTrenal-artery-CTerector spine)/SDerector-spine) were calculated. The single factor analysis of variance was used to analyze the difference of ΔCT, SNR and CNR among image groups with p < 0.05 being statistically significant. The subjective image scores of the groups were assessed blindly by two experienced physicians using a 5-point system and the score consistency was compared by the κ test. Results: Contrast medium dose in the 300 mgI kg−1 group was reduced by 50% compared with the 600 mgI kg−1 group, while radiation dose was similar between the two groups. The subjective scores were 4.00 ± 0.65, 4.50 ± 0.60 and 3.70 ± 0.80 for images at 70 keV (600 mgI kg−1 group), 40 keV (300 mgI kg−1 group) and 45 keV (300 mgI kg−1 group), respectively with good consistency between the two reviewers (p > 0.05). The 40 keV images in the 300 mgI kg−1 group had similar ΔCT (469.77 ± 86.95 HU vs 398.54 ± 73.68 HU) and CNR (15.52 ± 3.32 vs 18.78 ± 6.71) values as the 70 keV images in the 600 mgI kg−1) group but higher SNR values (30.19 ± 4.41 vs 16.91 ± 11.12, p < 0,05) Conclusion: Contrast dose may be reduced by 50% while maintaining image quality by using lower energy images combined with ASIR in renal dual-energy CTA. Advances in knowledge: Combined with ASIR and energy spectrum, can reduce the amount of contrast dose in renal CTA.

Download Full-text

Dual-Energy Spectral Computed Tomography With Adaptive Statistical Iterative Reconstruction for Improving Image Quality of Portal Venography

Journal of Computer Assisted Tomography ◽

10.1097/rct.0000000000000785 ◽

2018 ◽

Vol 42 (6) ◽

pp. 954-958

Author(s):

Weibing Wang ◽

Jinbai Huang ◽

Ai Wang ◽

Yun Li ◽

Jie Peng ◽

...

Keyword(s):

Computed Tomography ◽

Image Quality ◽

Iterative Reconstruction ◽

Dual Energy ◽

Adaptive Statistical Iterative Reconstruction ◽

Statistical Iterative Reconstruction ◽

Spectral Computed Tomography ◽

Portal Venography

Download Full-text

First experience with combined use of adaptive statistical iterative reconstruction and gemstone spectral imaging in spinal fusion CT images

10.7287/peerj.preprints.1306 ◽

2015 ◽

Author(s):

Fengdan Wang ◽

Yan Zhang ◽

Zhengyu Jin ◽

Richard Zwar

Keyword(s):

Image Quality ◽

Iterative Reconstruction ◽

Dual Energy ◽

Dual Energy Ct ◽

Metal Artifacts ◽

Adaptive Statistical Iterative Reconstruction ◽

Subjective Image Quality ◽

Gemstone Spectral Imaging ◽

Statistical Iterative Reconstruction ◽

Combined Use

Objective. To explore whether the image noises and the metal artifacts could be further managed by the combined use of two technologies, the adaptive statistical iterative reconstruction (ASIR) and the monochromatic imaging generated by gemstone spectral imaging (GSI) dual-energy CT. Materials and Methods. Fifty-one patients with 318 spinal pedicle screws were prospectively scanned with dual energy CT by using fast kV-switching GSI between 80 and 140 kVp. The monochromatic GSI images at 110 keV were reconstructed either without ASIR or with ASIR of various levels (30%, 50%, 70% and 100%). For these five sets of images, both objective and subjective image quality assessments were performed to evaluate the image quality. Results. With objective image quality assessment, the metal artifacts (measured by an artifacts index) significantly decreased when increasing levels of ASIR was utilized (p < 0.001). Moreover, adding ASIR to GSI also decreased the image noise (p < 0.001) and improved the signal-to-noise ratio (SNR, p < 0.001). With subjective image quality analysis, the inter-reader agreements were good, with intra-class correlation coefficients (ICC) of 0.89 to 0.99. Meanwhile, the visualization of the peri-implant soft tissue was improved at higher ASIR levels (p < 0.001). Conclusion. Combined use of ASIR and GSI is shown to decrease the image noise and improve the image quality in post-spinal fusion CT scans. Optimal results were achieved with ASIR levels of over 70%.

Download Full-text