The Use of Portable, Very Low-field (0.064T) MRI to Image Cochlear Implants: Metallic Image Artifact in Comparison to Traditional, Stationary 3T MRI

Abstract

Objective: To assess image artifact when imaging a cochlear implant (CI) with a conventional 3T MRI machine compared with a very low-field (0.064T) MRI. Patients: None. Intervention: Diagnostic study. Main Outcome Measure: Image artifact size associated with the CI affixed to an MRI phantom at very low-field 0.064T MRI versus 3T MRI. Results: The longest diameter of the image artifact was 125 mm for the 3T MRI and 86 mm for the 0.064T MRI, representing 45% longer image artifact generated in the 3T MRI. The actual volume of the imaging phantom was 1371 cm3. The volume of the image artifact was measured as 379 cm3 in the 3T MRI, representing a loss of 27.6% of the actual volume of the imaging phantom. The volume of image artifact was measured as 170 cm3 in the 0.064T MRI, representing a loss of 12.4% of the phantom volume. Conclusions: 3T MRI had better image quality. This result was not surprising given that larger magnetic field strength is known to provide higher resolution. There was 15% less image artifact generated in the very low-field MRI machine compared with a conventional 3T device. And there was also subjectively increased distortion of the imaging phantom at 3T MRI compared with the 0.064T MRI. With minimized safety concerns and a much lower cost than conventional 3T machines, very low-field scanners may find expanded clinical uses. This preclinical study explores the potential utility of very low-field MRI in scanning CI recipients.