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Electromagnetic Interference Artifacts in Digital Radiography Caused by Left Ventricular Assist Devices (LVAD)

K Little

Z Lu1 , K Little1*, I Reiser1 , V Kagan2 , A Sanchez1 , H MacMahon1 , (1) Department of Radiology, University of Chicago, Chicago, IL, (2) Thoracic Surgery, The University of Chicago Medicine & Biological Sciences, Chicago, IL


PO-BPC-Exhibit Hall-13 (Saturday, March 5, 2016)  Room: Exhibit Hall

Purpose: To identify and characterize artifacts caused by left ventricular assist devices (LVAD) on digital detector radiography images, and to investigate approaches to reduce these artifacts.

Methods: When a digital detector is used to acquire a radiograph of a patient with an implanted device that is not electromagnetically compatible with the detector, electromagnetic interference (EMI) artifacts can occur on the acquired images. This was brought to our attention on multiple patients with different models of LVADs. Although the artifacts have similar repetitive linear patterns, the appearance, extent, and severity of the artifact varies widely between LVAD models and between patients. We tested a HeartMate II device with an anthropomorphic lung phantom on two digital detectors (Canon 70C, GE FlashPad) to study how distance, LVAD rotation speed, and the usage of a grid affect EMI artifacts.

Results: The EMI artifacts on images were caused by the LVAD device. This was confirmed by acquiring two images with the LVAD on and off. There was no artifact in the LVAD-off image. The EMI artifacts were affected by the distance between the LVAD device and the detector. Increasing the distance reduced the severity. The EMI artifacts were also affected by the rotation speed of the LVAD, and the artifacts were barely visible at the lowest motor speed tested. Adding a spacer between the patient and the detector may mitigate the artifacts. In addition, at least one vendor has developed an EMI artifact reduction feature to be used during image acquisition if EMI is known to exist.

Conclusion: With more digital radiography units replacing computed radiography units, it is important to understand the physical limitations of digital detectors and to be vigilant for electromagnetic interference artifacts that are unique to the image acquisition process of such digital detector radiography units.

Funding Support, Disclosures, and Conflict of Interest: This work was supported in part by the RSNA/AAPM Imaging Physics Residency Program Grant.

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