Motion artifacts in cardiac CT - The Novacor left ventricular assist device and its implications for clinical imaging

Purpose: Cardiovascular applications of CT are primarily limited by tempora l resolution of the scanner. Recent development in scanner technology has g reatly increased temporal resolution. We here describe a standardized metho d of assessing temporal properties of various CT techniques. Material and Methods: The Novacor left ventricular assist device was mounte d in a water-filled circulation phantom and scanned at different pump rates with a spiral CT unit and an electron beam unit. We also evaluated the use of EGG-triggered subsecond scanning on a spiral CT unit. Results: Using the fastest conventional scanning protocol, severe motion ar tifacts occurred. These artifacts could not be reproduced from image to ima ge, even if the pump rate was adjusted to scan rate (1/s). Electron beam to mography (EBT) reproducibly yielded few artifacts at 100 ms and practically no artifacts at 50 ms scanning time. Even without EGG-triggering, pump mot ion could be reproduced as a cine-cycle. With the EGG-triggered partial sca nning CT technique, limited motion artifacts could be reproduced during dia stole at a heart rate of 70-80 beats/min. Conclusion. The Novacor ventricular assist device may serve as a benchmark test in the evaluation of new scanning techniques for cardiovascular CT. Wh ile EBT presently remains the only CT technique to freeze cardiac motion th roughout its cycle, EGG-triggered subsecond scans may, under certain condit ions, capture cardiac anatomy in diastole.