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. 2015 May 20;16(5):11531-49.
doi: 10.3390/ijms160511531.

Optimal Scanning Protocols for Dual-Energy CT Angiography in Peripheral Arterial Stents: An in Vitro Phantom Study

Abdulrahman Almutairi  1   2 , Zhonghua Sun  3 , Zakariya Al Safran  4 , Abduljaleel Poovathumkadavi  5 , Suha Albader  6 , Husam Ifdailat  7
Affiliations

Optimal Scanning Protocols for Dual-Energy CT Angiography in Peripheral Arterial Stents: An in Vitro Phantom Study

Abdulrahman Almutairi et al. Int J Mol Sci. .

Abstract

Objective: To identify the optimal dual-energy computed tomography (DECT) scanning protocol for peripheral arterial stents while achieving a low radiation dose, while still maintaining diagnostic image quality, as determined by an in vitro phantom study.

Methods: Dual-energy scans in monochromatic spectral imaging mode were performed on a peripheral arterial phantom with use of three gemstone spectral imaging (GSI) protocols, three pitch values, and four kiloelectron volts (keV) ranges. A total of 15 stents of different sizes, materials, and designs were deployed in the phantom. Image noise, the signal-to-noise ratio (SNR), different levels of adaptive statistical iterative reconstruction (ASIR), and the four levels of monochromatic energy for DECT imaging of peripheral arterial stents were measured and compared to determine the optimal protocols.

Results: A total of 36 scans with 180 datasets were reconstructed from a combination of different protocols. There was a significant reduction of image noise with a higher SNR from monochromatic energy images between 65 and 70 keV in all investigated preset GSI protocols (p < 0.05). In addition, significant effects were found from the main effect analysis for these factors: GSI, pitch, and keV (p = 0.001). In contrast, there was significant interaction on the unstented area between GSI and ASIR (p = 0.015) and a very high significant difference between keV and ASIR (p < 0.001). A radiation dose reduction of 50% was achieved.

Conclusions: The optimal scanning protocol and energy level in the phantom study were GSI-48, pitch value 0.984, and 65 keV, which resulted in lower image noise and a lower radiation dose, but with acceptable diagnostic images.

Keywords: dual-energy CT; gemstone spectral imaging; image noise; monochromatic image; peripheral arterial stent.

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Figures

Figure 1
Figure 1
(A–C) show the comparison of Noise Level at different kiloelectron voltage (keV) with the three preset GSI protocols and three pitch values, while Figure (D,E) represent the mean of CT value in unstented area and all stents with these scanning protocols.
Figure 1
Figure 1
(A–C) show the comparison of Noise Level at different kiloelectron voltage (keV) with the three preset GSI protocols and three pitch values, while Figure (D,E) represent the mean of CT value in unstented area and all stents with these scanning protocols.
Figure 2
Figure 2
A total of 13 stents (No. 7 and 14 were not included due to difficulty placing region of interest in the area) with axial and coronal reformatted images were demonstrated with three GSI protocols (A–C: GSI-36, GSI-48, and GSI-51, respectively) and three pitch values at a keV of 65.
Figure 2
Figure 2
A total of 13 stents (No. 7 and 14 were not included due to difficulty placing region of interest in the area) with axial and coronal reformatted images were demonstrated with three GSI protocols (A–C: GSI-36, GSI-48, and GSI-51, respectively) and three pitch values at a keV of 65.
Figure 3
Figure 3
(A–E) A comparison of relationship between noise levels measured with different GSI protocols and pitch values at 65 keV with different diameters of stents; (F) represents the mean of CT values measured in all stents with use of three GSI and pitch protocols.
Figure 3
Figure 3
(A–E) A comparison of relationship between noise levels measured with different GSI protocols and pitch values at 65 keV with different diameters of stents; (F) represents the mean of CT values measured in all stents with use of three GSI and pitch protocols.
Figure 4
Figure 4
(A,B) are graphic representations showing the noise level when ASIR is used within the both unstented and stented areas; while (C,D) represent the means of SNR when ASIR is used.
Figure 4
Figure 4
(A,B) are graphic representations showing the noise level when ASIR is used within the both unstented and stented areas; while (C,D) represent the means of SNR when ASIR is used.
Figure 5
Figure 5
Box plots demonstrate the radiologist’s evaluation of the image quality using a 3-point scale. The red line within the yellow box indicates the median of the values. The red line at the bottom of the box corresponds to the 25th percentile, and the one at the top is the 75th percentile. The range between these two lines (i.e., the length of the box) is the inter Quartile Range (IQR). The lower cross line is 1.5 IQR below the 25th percentile, the upper cross line is 1.5 IQR above the 75th percentile. Individual observations beyond either of these cross line are outliners, shown as green circles.
Figure 6
Figure 6
Photograph of the phantom with stents insertion.
Figure 7
Figure 7
The region of interest was placed in the inner stent lumen for measurement of image noise. The colored circles indicate measurement inside the stent lumen.
See this image and copyright information in PMC

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