Room: AAPM ePoster Library
Purpose: This investigation describes the detection and characterization of digital radiographic image artifacts related to left ventricular assist device (LVAD) use in routine clinical practice.
Methods: A radiologist reported “grid-like” artifacts in gridless mobile radiographs of at least 28 cardiac patients with an LVAD [Impella® (ABIOMED, Inc., Danvers, MA) or Heartmate 3™ (Abbott Vascular, Santa Clara, CA)]. A sample HeartMate 3™ was obtained for experimentation and operated at a nominal speed of 7000 RPM, pulsatility index of 6.0, and power set to 3.0 W. Images were obtained on a mobile digital radiography unit [Mobile Diagnost wDR (Philips Healthcare, Andover, MA)] under manufacturer-specified calibration conditions in an attempt to reproduce and characterize the artifact. Artifact prominence was assessed using the noise-corrected coefficient of variation (COV) measured from image pixel values linearized to detector incident exposure. Images from seven other digital radiography devices spanning three vendors including both wireless and fixed (tethered) digital detectors and a computed radiography (CR) device were also obtained to test artifact prevalence.
Results: All digital detectors were subject to LVAD artifact except for the CR device. Therefore, LVAD interference with wireless detector signal transmission was ruled out as an artifact source due to similar artifact prominence in both wireless and tethered digital detector setups. Median artifact COV across the detector field of view was found to be LVAD orientation-dependent, and it followed a power law proportionality to the LVAD distance (d) from the detector such that COV?d? where p<0. Artifact prominence was also found to decrease at higher detector entrance exposure (X) according to COV?X?¹.
Conclusion: LVADs operating near digital radiographic detectors produce artifacts which mimic classical grid artifacts in clinical practice. Medical Physics 3.0 support in the clinical setting was employed to deliver quick and definitive confirmation of artifact etiology and factors affecting artifact prominence.