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KMID : 1149020170190020097
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Journal of Korean Society of Computed Tomographic Technology
2017 Volume.19 No. 2 p.97 ~ p.106
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Comparison of Multi Detector and Dual-Layer Spectral Detector CT in Angiography of the Aorta; Contrast Protocol
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Chung Yong-Hwan
Lee Jae-Hyun
Lee Jong-Min
Kim Tae-Eun
Kang Seung-Won
Gwon Sun-Ahn
Min Kwan-Hong
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Abstract
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Purpose : To evaluate the usefulness of the spectral technique of Dual-Layer Spectral Detector CT using low flow-rate and volume of contrast agent for CT angio Aorta.
Materials and Methods : From October to December 2016, We performed this study on 64 patients who visited CT Angio Aorta. The equipment used is Brilliance iCT, 256-Slice Multi Detector CT and IQON, 128-Slice Dual-Layer Spectral Detector CT. MDCT was tested at 100kVp, 250mAs. The arterial phase was obtained 15 seconds after the CT number reached 150 HU by setting the ROI to the ascending aorta of the carina level. The flow rate of the contrast agent was 3.5 cc/sec, and the amount was fixed at 130 cc regardless of body weight. In addition, 30 cc of normal saline was injected. Image reconstruction was reconstructed using FBP, a conventional technique. SDCT was tested at 120kVp, 120mAs. The arterial phase was obtained 15 seconds after the CT number reached 90 HU by setting the ROI to the ascending aorta of the carina level. The flow rate of the contrast agent was 1.5 cc/sec, and the amount was fixed to 50 cc regardless of body weight. Image reconstruction was performed with the spectral technique MonoE 60keV using SpDS. The radiation doses were compared using the DLP values shown in the Exam information provided by PACS. In the quantitative image evaluation, CNR was calculated and compared using the average value measured by three radiological technologist with a career of 5 years or more, The measurement sites were the carina level Descending aorta, SMA, and right common femoral artery. CT numbers and standard deviations were measured. The qualitative image evaluation was evaluated by a radiologist and a resident majoring radiology using 4 point scale method Brachiocephalic artery, Celiac artery, SMA, and renal artery were evaluated for aortic enhancement.
Results : Results of radiation dose comparison, The DLP values were 664~1090mGy * cm in MDCT and 716~1167mGy * cm in SDCT. There was no statistically significant difference between the two methods.(P = 0.2748) Results of quantitative evaluation, The CT number and noise value are given in the Descending aorta The mean MDCT was 450 ± 10 and 15.47±2, the mean SDCT was 281±45 and 10.7±1.6, in SMA The mean MDCT was 458±7 and 18.7±1.88, the mean MDCT was 280±44 and 13.88±2.13, in Right Common femoral artery The mean of MDCT was 432±13 and 15.49 ± 3.87, and the mean of SDCT was 253±3 and 11.35±2.72. CNR was 93±11 for MDCT and 108±14 for SDCT in Descending aorta, In SMA, mean MDCT was 76±7, mean SDCT was 86±13, In the right common femoral artery, the mean MDCT was 95±2 and the mean SDCT was 103±19. As a result of the qualitative evaluation, there was no statistically significant difference between the two methods. (P > 0.05)
Conclusion : Spectral reconstruction using SDCT for CT angio aorta can reduce the amount of contrast agent by 62.5% and decrease injection rate per second to 1.5cc / sec without degradation of image quality.
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KEYWORD
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CT Angiography, Dual-Layer Spectral Detector CT, CT number, Noise, CNR, Contrast agent
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