Low Tube Voltage and Iterative Model Reconstruction in Follow-up CT Angiography After Thoracic Endovascular Aortic Repair: Ultra-low Radiation Exposure and Contrast Medium Dose

Ping Hou; Xiangnan Feng; Jie Liu; Xiaopeng Wang; Yaojun Jiang; Leigang Dong; Jianbo Gao

doi:10.1016/j.acra.2017.11.001

Low Tube Voltage and Iterative Model Reconstruction in Follow-up CT Angiography After Thoracic Endovascular Aortic Repair: Ultra-low Radiation Exposure and Contrast Medium Dose

Acad Radiol. 2018 Apr;25(4):494-501. doi: 10.1016/j.acra.2017.11.001. Epub 2017 Dec 14.

Authors

Ping Hou¹, Xiangnan Feng², Jie Liu¹, Xiaopeng Wang¹, Yaojun Jiang¹, Leigang Dong¹, Jianbo Gao³

Affiliations

¹ Department of Radiology, The First Affiliated Hospital of Zhengzhou University, No. 1, East Jianshe Road, Zhengzhou, Henan Province 450052, China.
² School of Economics and Management, Southwest Jiaotong University, Chengdu, China.
³ Department of Radiology, The First Affiliated Hospital of Zhengzhou University, No. 1, East Jianshe Road, Zhengzhou, Henan Province 450052, China. Electronic address: cjr_gaojianbo@sina.com.

PMID: 29249576
DOI: 10.1016/j.acra.2017.11.001

Abstract

Rationale and objectives: This study aimed to investigate the feasibility of reducing radiation exposure and contrast medium (CM) dose in follow-up computed tomography angiography (CTA) after thoracic endovascular aortic repair (TEVAR) using low tube voltage and knowledge-based iterative model reconstruction (IMR).

Materials and methods: Thirty-six patients that required follow-up CTA after TEVAR were included in this intra-individual study. The conventional protocol with standard tube voltage of 120 kVp and CM volume of 70 mL was applied in the first follow-up CTA of all the patients (control group A). The ultra-low CM dose protocol with low tube voltage of 80 kVp and weight-adapted CM volume of 0.4 mL/kg was utilized in the second follow-up CTA (study group B). Set A.FBP (group A filtered back-projection) contained images for group A that were reconstructed through FBP method. Three sets (B.FBP, B.HIR, and B.IMR) for group B were reconstructed using three methods, FBP, hybrid iterative reconstruction (HIR), and IMR, respectively. Objective measurements including aortic attenuations, image noise, contrast-to-noise ratios (CNRs), and figure of merit of CNR (FOM_CNR), and subjective rating scores of the four image sets were compared.

Results: Compared to the images in set A.FBP, the images in set B.IMR had better quality in terms of equivalent attenuation values, equivalent subjective scores, lower noise, higher or equivalent CNRs, and higher FOM_CNR. The quality of images in sets B.FBP and B.HIR was unacceptable. The radiation exposure and CM dose in group B were 1.94 mGy and 28 ± 5 mL, respectively, representing reductions of 77.6% (P < .001) and 60% (P < .001) as compared to those in group A.

Conclusions: In follow-up examinations after TEVAR, CTA with ultra-low radiation exposure and CM dose is feasible using low tube voltage and IMR for nonobese patients.

Keywords: Low-tube-voltage; follow-up CT angiography; iterative model reconstruction.

MeSH terms

Adult
Aged
Aorta, Thoracic / diagnostic imaging*
Aorta, Thoracic / surgery*
Computed Tomography Angiography / methods*
Contrast Media / administration & dosage
Endovascular Procedures
Feasibility Studies
Female
Humans
Image Processing, Computer-Assisted / methods*
Male
Middle Aged
Prospective Studies
Radiation Dosage
Radiation Exposure
Signal-To-Noise Ratio
Single-Blind Method

Substances

Contrast Media