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Congress: ECR25
Poster Number: C-21700
Type: Poster: EPOS Radiologist (scientific)
Authorblock: A. Choux1, Z. Yin2, C. L. Kim2, A. Pourmorteza1; 1Atlanta, GA, GA/US, 2Niskayuna, NY/US
Disclosures:
Arnaud Choux: Research/Grant Support: GE HealthCare
Zhye Yin: Employee: GE HealthCare
Chang Lyong Kim: Employee: GE HealthCare
Amir Pourmorteza: Grant Recipient: GE HealthCare
Keywords: Computer applications, CT, CT-Angiography, CT-Quantitative, Physics, Cancer
Purpose Photon-counting detectors (PCDs) provide multi-contrast agent (CA) separation through K-edge imaging [1]. [fig 1] Timely administration of two contrast agents can create synchronized anatomical maps in various perfusion phases, eliminating the need for multi-phase scans. This approach improves efficiency and reduces patient radiation exposure. Deep-Si PCDs, featuring eight adjustable thresholds, offer greater flexibility in capturing the K-edge of multiple CAs compared to current clinical PCD-CTs, which are limited to a maximum of four energy settings and are based on high-Z Cd(Zn)Te....
Read more Methods and materials A cylindrical test object (diameter=20cm, height=5cm) was filled with ballistic gel and contained 137 2-mL test tubes filled with calibrated concentrations of materials including: iodine-, gadolinium, tantalum, bismuth-based contrast agents and their mixtures and dilutions in water and simulated blood. [fig 2] Each material and its water dilutions is represented as a line in the multi-energy space. The angle between these lines was chosen as the metric of spectral separability. We scanned the phantom on a prototype deep-Si PCD-CT [2]. The...
Read more Results Capturing the K-edge of CAs significantly (t-test, p<0.01) improved the spectral separability of iodine from gadolinium (15.3° vs 19.5°), bismuth (6.1° vs 9.5°), and tantalum (14.2° vs 29.3°) for setting1 vs setting2. Furthermore, blood-CA separability was increased for all CAs with setting2. [fig 3] . Signal difference to noise ratio for iodine-based CA and gadolinium based CA were also improved. Specifically, the K-edge of gadolinium became more prominent in the images acquired with the improved threshold settings [fig 4] .
Read more Conclusion One major limitation of this study was its small sample size. larger studies with more diverse test objects are warranted. Another limitation was the use of FBP reconstruction algorithm. Using model-based, iterative, and deep-learning based reconstruction algorithms may further improve the noise property and spectral separability of the system.K-edge-optimized threshold selection improved simultaneous spectral separability of multiple CAs on the deep-Si PCD-CT scanner. 
Read more References 1- Willemink, Martin J., et al. "Photon-counting CT: technical principles and clinical prospects." Radiology 289.2 (2018): 293-312.2- Holmes, Thomas Wesley, et al. "Ultrahigh-resolution K-edge imaging of coronary arteries with prototype deep-silicon photon-counting CT: initial results in phantoms." Radiology 311.3 (2024): e231598.
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