Abstract
ObjectiveOne of the main drawbacks associated with Dual Energy Computed Tomography Angiography (DECTA) is the risk of developing contrast medium-induced nephropathy (CIN). The aim of the present study was firstly, to design an optimal CT imaging protocol by determining the feasibility of using a reduced contrast medium volume in peripheral arterial DECTA, and secondly, to compare the results with those obtained from using routine contrast medium volume.MethodsThirty four patients underwent DECTA for the diagnosis of peripheral arterial disease. They were randomly divided into two groups: Group 1 (routine contrast volume group) with n = 17, injection rate 4–5 ml/s, and 1.5 ml/kg of contrast medium, and Group 2 ((low contrast volume group), with n = 17, injection rate 4–5ml/s, and contrast medium volume 0.75 ml/kg. A fast kilovoltage—switching 64-slice CT scanner in the dual-energy mode was employed for the study. A total of 6 datasets of monochromatic images at 50, 55, 60, 65, 70 and 75 keV levels were reconstructed with adaptive statistical iterative reconstruction (ASIR) at 50%. A 4-point scale was the tool for qualitative analysis of results. The two groups were compared and assessed quantitatively for image quality on the basis of signal-to-noise ratio (SNR) and contrast-to-noise-ratio (CNR). Radiation and contrast medium doses were also compared.ResultsThe overall mean CT attenuation and mean noise for all lower extremity body parts was significantly lower for the low volume contrast group (p<0.001), and varied significantly between groups (p = 0.001), body parts (p<0.001) and keVs (p<0.001). The interaction between group body parts was significant with CT attenuation and CNR (p = 0.002 and 0.003 respectively), and marginally significant with SNR (p = 0.047), with minimal changes noticed between the two groups. Group 2 (low contrast volume group) displayed the lowest image noise between 65 and 70 keV, recorded the highest SNR and CNR at 65 keV, and produced significantly lower results with respect to contrast medium volume and duration of contrast injection (p<0.001). The effect of radiation dose was not statistically significant between the two groups.ConclusionsDECTA images created at 65 keV and 50% ASIR with low contrast medium volume protocol, yielded results that were comparable to routine contrast medium volume, with acceptable diagnostic images produced during the evaluation of peripheral arteries.
Highlights
Computed tomography angiography (CTA) has, over the last decade, become the preferred choice for diagnosing and evaluating peripheral arterial disease (PAD) in a manner comparable to invasive angiography [1]
The interaction between group body parts was significant with CT attenuation and Contrast-to-Noise Ratio (CNR) (p = 0.002 and 0.003 respectively), and marginally significant with Signal-toNoise Ratio (SNR) (p = 0.047), with minimal changes
Dual Energy CT Angiography of Peripheral Arterial Disease noticed between the two groups
Summary
Computed tomography angiography (CTA) has, over the last decade, become the preferred choice for diagnosing and evaluating peripheral arterial disease (PAD) in a manner comparable to invasive angiography [1]. Patients diagnosed with PAD are usually evaluated with CTA, which requires administration of iodinated contrast medium. With the onset of the 64-slice and post 64-slice CT era, scanning of the lower extremities could be achieved routinely in less than 10 seconds. The fast scan speed may outrun the contrast bolus, and large quantities of contrast volume are not essential for vascular studies [5]. Low kilovoltage (kVp) levels have been shown to improve contrast enhancement in CTA [6, 7]. The disadvantages of this procedure lie in the beam hardening artefacts and the increase of image noise
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