Abstract 15601: Optimal Virtual Monoenergetic Settings for Spectral Ct With a Dual-Layer Detector: A Breakthrough in Evaluating the Patency of the Coronary Arterial Lumen With a Metallic Stent in a Real-World Study

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Introduction: Evaluation of the patency of a metallic stent in coronary arteries using CT is difficult because the metallic stent causes a blooming artifact. The CT values of metallic stents are influenced by tube kilovoltage (kV). Recent spectral CT with a dual-layer detector can generate CT images at any kiloelectron voltage (keV) (range: 40-200) after ordinary acquisition using virtual monoenergetic settings (VMS). Hypothesis: Using a new spectral CT, we can determine the optimal VMS for evaluating the patency of stents in coronary arteries. Methods: We performed enhanced 128 slice Spectral CT 7500 scans with a dual-layer detector in 35 patients with CAC who underwent implantation of a metallic stent in coronary arteries (tube voltage: 120 kV). After scanning, VMS images at various keV values were created from the spectral-based images. We measured the mean CT values of the metallic stent, coronary artery calcification (CAC), lumen in the left coronary artery (LCA), and fat tissue around the coronary arteries in the axial images at each keV in the early phase with contrast. Results: Lower keV values were associated with markedly increased mean CT values of the metallic stent and CAC. The CT values of the lumen in the LCA were moderately increased. Conversely, the CT values of fat tissue were slightly decreased. The greatest differences in mean CT values between the metallic stent and lumen in the LCA were observed at 40-50 keV, however, those between the metallic stent and CAC were observed at 110-180 keV. The optimal keV for achieving the best contrast between the CT values of the metallic stent, CAC, and the lumen in the LMA at each patient was influenced by age, male sex. Conclusions: The metallic stent, CAC, lumen of the LCA, and fat tissue exhibit unique characteristics. When conventional rather than spectral CT is used to evaluate the patency of a metallic stent in coronary arteries, it is necessary to determine the optimal tube voltage based on the age and male sex of the patient.

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