SU‐FF‐I‐33: A Technical Solution to Avoid Partial Scan Artifacts in Myocardial Perfusion Imaging Using MDCT

Abstract

Purpose: Partial scan reconstruction methods improve temporal resolution but cause large CT number fluctuations in MDCT systems. The purpose of this study was to assess the feasibility of a new approach to solve this problem. Method and Materials: An anthropomorphic cardiac phantom was scanned on a dual‐source CT scanner (Siemens Definition) using several perfusion modes both with and without ECG‐gating. An additional ECG‐gated acquisition was conducted using the ECG‐signal synchronized with the gantry rotation. The central insert of the cardiac phantom was replaced with a water‐filled tank containing a syringe filled with different iodine solutions (500, 1000, 1500 and 2000 HU). Images were reconstructed using both full (360°, 330 ms) and partial (180° + fan angle, 83 ms) approaches. A ring ROI was placed outside the syringe concentrically with the iodine circle and the mean CT number fluctuations were plotted vs. time. In addition, in‐vivo animal data were acquired using the regular perfusion mode and the mode when the pig's ECG was synchronized with the gantry rotation. A simple x‐ray detector was used to generate a so‐called ‘once‐around’ signal for every gantry rotation. This signal was then modified and used to pace the pig's heart. Results: When the ECG signal was synchronized with the gantry rotation, the same cardiac phase always corresponded to the same x‐ray tube positions and, hence, the same scattering geometry. As a result, the range in the CT number fluctuations was reduced from 20 HU for the regular perfusion mode down to only 3 HU for the synchronized mode. Conclusion: The new approach for myocardial CT perfusion based on synchronizing the ECG signal with the x‐ray tube position significantly improves the quality of the perfusion data by reducing the CT number fluctuations. Conflict of Interest: ANP, OPD, and CHM receive research support from Siemens Medical Solutions.