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Srinivas SA, Cauley SF, Stockmann JP, Sappo CR, Vaughn CE, Wald LL, Grissom WA, Cooley CZ. External Dynamic InTerference Estimation and Removal (EDITER) for low field MRI. Magn Reson Med 2022; 87:614-628. [PMID: 34480778 PMCID: PMC8920578 DOI: 10.1002/mrm.28992] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 07/25/2021] [Accepted: 08/10/2021] [Indexed: 02/03/2023]
Abstract
PURPOSE Point-of-care MRI requires operation outside of Faraday shielded rooms normally used to block image-degrading electromagnetic interference (EMI). To address this, we introduce the EDITER method (External Dynamic InTerference Estimation and Removal), an external sensor-based method to retrospectively remove image artifacts from time-varying external interference sources. THEORY AND METHODS The method acquires data from multiple EMI detectors (tuned receive coils as well as untuned electrodes placed on the body) simultaneously with the primary MR coil during and between image data acquisition. We calculate impulse response functions dynamically that map the data from the detectors to the time varying artifacts then remove the transformed detected EMI from the MR data. Performance of the EDITER algorithm was assessed in phantom and in vivo imaging experiments in an 80 mT portable brain MRI in a controlled EMI environment and with an open 47.5 mT MRI scanner in an uncontrolled EMI setting. RESULTS In the controlled setting, the effectiveness of the EDITER technique was demonstrated for specific types of introduced EMI sources with up to a 97% reduction of structured EMI and up to 76% reduction of broadband EMI in phantom experiments. In the uncontrolled EMI experiments, we demonstrate EMI reductions of up to 99% using an electrode and pick-up coil in vivo. We demonstrate up to a nine-fold improvement in image SNR with the method. CONCLUSION The EDITER technique is a flexible and robust method to improve image quality in portable MRI systems with minimal passive shielding and could reduce the reliance of MRI on shielded rooms and allow for truly portable MRI.
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Affiliation(s)
- Sai Abitha Srinivas
- Vanderbilt University Institute of imaging science, Nashville, TN, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
| | - Stephen F Cauley
- Harvard Medical School, Boston, MA, United States
- Dept. of Radiology, Massachusetts General Hospital, Athinoula A Martinos Center for Biomedical Imaging, Boston, MA, United States
| | - Jason P Stockmann
- Harvard Medical School, Boston, MA, United States
- Dept. of Radiology, Massachusetts General Hospital, Athinoula A Martinos Center for Biomedical Imaging, Boston, MA, United States
| | - Charlotte R Sappo
- Vanderbilt University Institute of imaging science, Nashville, TN, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
| | - Christopher E Vaughn
- Vanderbilt University Institute of imaging science, Nashville, TN, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
| | - Lawrence L Wald
- Harvard Medical School, Boston, MA, United States
- Dept. of Radiology, Massachusetts General Hospital, Athinoula A Martinos Center for Biomedical Imaging, Boston, MA, United States
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, United States
| | - William A Grissom
- Vanderbilt University Institute of imaging science, Nashville, TN, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Electrical Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Radiology, Vanderbilt University, Nashville, TN, United States
| | - Clarissa Z Cooley
- Harvard Medical School, Boston, MA, United States
- Dept. of Radiology, Massachusetts General Hospital, Athinoula A Martinos Center for Biomedical Imaging, Boston, MA, United States
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