Andrew Sher MD, Abstract Co-Author: Research Grant, Koninklijke Philips NV

Abed Ghandour MD, Abstract Co-Author: Nothing to Disclose

Robert C. Gilkeson MD, Abstract Co-Author: Research Consultant, Riverain Technologies, LLC Research support, Koninklijke Philips NV Research support, Siemens AG

Hiram Bezerra, Abstract Co-Author: Nothing to Disclose

David L. Wilson PhD, Abstract Co-Author: Co-owner, BioInVision Inc Research Grant, Koninklijke Philips NV

Prabhakar Rajiah MD, FRCR, Presenter: Institutional Research Grant, Koninklijke Philips NV

To identify the optimal monoenergetic level for evaluation of coronary arteries using a novel spectral detector CT (SDCT). 

16 patients had coronary CTAs with a SDCT scanner (Philips Healthcare), with standard clinical protocol. Monoenergetic images were generated and analyzed in 10 keV increments from 40 to 180 keV. Attenuation, noise, SNR & CNR from separate coronary artery segments (LM, LAD, LCX, RCA) were measured in identical ROIs on the monoenergetic and polychromatic (120 kVp) image sets. Images were viewed at a set window width(600) and level (200) and a five-point scale was used to evaluate enhancement (1=Non-diagnostic,5=Excellent), image noise (1=Major noise, non-diagnostic, 5 = No noise) and overall image quality (1=Non-diagnostic, 5=Excellent, no artifact).  

The mean attenuation & noise were highest at 40 keV (1293.1 HU ± 519.5; 131.4 ± 77.4 (p <.001), respectively). Attenuation and noise decreased as energy increased. The SNR was not statistically different between the 40, 50, and 60 keV studies (range 13.2-13.7) and were all significantly higher than the polychromatic 120 kVp images. Peak SNR occurred at 50 keV (13.7 ± 9.4 vs. polychromatic SNR 9.7 ± 5.3, P<.05). Peak CNR occurred at 50 keV and was slightly higher than on the polychromatic images (20.7 ± 11.5 vs. 18.2 ± 8.6, P <. 05). At the optimal SNR energy level of 50 keV, images showed 134% higher mean attenuation and 89% higher image noise versus routine polychromatic images. At the 50 and 60 keV monoenergy level, overall image quality significantly lower in the monoenergetic images. At 70 keV, monoenergetic images were approximately 7.5% higher in attenuation (350.1 ± 135.4 vs. 325.8 ± 121.8, P<.01) and 25% higher in SNR (12.1 ± 7.7 vs. 9.7 ± 5.3, P<.001) than 120 kvP images, and this energy level was found to have higher overall image quality compared to the polychromatic images (4.3± .6 vs. 3.8± .8, p < .05).   

SDCT monoenergetic coronary angiography can enhance the CT attenuation of iodine. Balancing increased attenuation with image quality is essential, as lower energy increases image noise. Monoenergetic level of 70 keV can provide an effective balance between higher attenuation and SNR while improving image quality. 

SDCT enables monochromatic coronary angiography, allowing increased coronary attenuation and SNR compared to standard polychromatic images while improving image quality.  

Sher, A, Ghandour, A, Gilkeson, R, Bezerra, H, Wilson, D, Rajiah, P, Optimal Monoenergetic Level for Evaluation of Coronary Arteries with a Novel Spectral Detector CT Technology.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045791.html