Abstract
The purpose of this study is to prospectively compare image quality and radiation dose using 100- and 120-kVp techniques for carotid CT angiography. Forty consecutive patients were alternated between the 100 kVp group and 120 kVp group while all other scanning parameters were kept constant. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for locations along the carotid artery, vertebral artery and circle of Willis. Three radiologists independently assessed subjective image quality including confidence of visualization using a five-point scale. Effective dose was calculated using the dose length product (DLP). CNR and SNR were either similar or better when using 100 kVp for all vessels. Subjective image quality was similar between techniques. Mean effective dose was 36% lower for the 100 kVp than the 120 kVp technique. This study demonstrated that using 100 kVp technique provides 36% dose reduction with significantly higher objective image quality and nonsignificantly higher subjective image quality compared to the 120 kVp technique.
Highlights
Stroke is the third leading cause of death and is a major source of disability in Canada [1]
Comparison of patient characteristics between both groups did not reveal any significant differences for age, sex, Body mass index (BMI), and neck size and substantiates the validity of our results for subjective and objective measurements (Table 1)
Two right-sided internal carotid artery (ICA) measurements were excluded from the 100 kVp group due to one complete occlusion and one stent
Summary
Stroke is the third leading cause of death and is a major source of disability in Canada [1]. Evaluation of the carotid arteries for occlusive disease is standard amongst patients with ischemic stroke. Carotid computed tomography angiography (CTA) is rapid, non-invasive, and a reliable method of evaluating the carotid arteries with easy accessibility at many Canadian centres. Other non-invasive imaging modalities are available, such as doppler carotid sonography and magnetic resonance angiography (MRA) [2]. Both MRI and ultrasound benefit from having no ionizing radiation, there are limitations compared with CT. Figure 1: 79-year-old women in the 120 kV group demonstrating background noise and muscle SI measurement for the supra-aortic common carotid and vertebral arteries
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