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.
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 (FOMCNR), 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 FOMCNR. 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.
['Hou|Ping|P|', 'Feng|Xiangnan|X|', 'Liu|Jie|J|', 'Wang|Xiaopeng|X|', 'Jiang|Yaojun|Y|', 'Dong|Leigang|L|', 'Gao|Jianbo|J|']
D000328:Adult D000368:Aged D001013:Aorta, Thoracic D000072226:Computed Tomography Angiography D003287:Contrast Media D057510:Endovascular Procedures D005240:Feasibility Studies D005260:Female D006801:Humans D007091:Image Processing, Computer-Assisted D008297:Male D008875:Middle Aged D011446:Prospective Studies D011829:Radiation Dosage D000069079:Radiation Exposure D059629:Signal-To-Noise Ratio D016037:Single-Blind Method
iterative model reconstruction follow-up CT angiography Low-tube-voltage