Cronin, Alicia E.; D’Astous, Alexandre; Williams, Nathan; Gu茅nette, Antoine; Salakhov, Aimee; Stubblefield, Seth; McKnight, Colin D.; Narisetti, Lipika; Sriram, Subramaniam; Smith, Seth A.; Robison, Ryan K.; Gilbert, Guillaume; Cohen-Adad, Julien; O’Grady, Kristin P. (2026). . Magnetic Resonance in Medicine.
Multi-echo gradient echo (ME-GRE) is an MRI technique that can improve visualization of gray and white matter in the spinal cord and help detect lesions in people with multiple sclerosis (MS). However, breathing can interfere with these scans, causing image artifacts and signal loss. We developed a correction method that uses a one-dimensional (1D) phase navigator, a brief MRI measurement that tracks magnetic field changes, before image data are collected. This approach reduces measurement errors and does not require separate monitoring of breathing. We tested the method at 3T MRI in the thoracic spinal cord of 20 healthy volunteers and three people with MS. Compared with standard image reconstruction, navigator correction improved signal quality and gray-to-white matter contrast, reduced breathing-related ghosting artifacts, and provided clearer visualization of spinal cord structures. Preliminary results in the three participants with MS also showed fewer artifacts, clearer anatomy, and improved visibility of lesions. These findings suggest that the proposed navigator correction can improve the quality and reliability of thoracic spinal cord ME-GRE imaging and may increase its usefulness for evaluating MS.
FIGURE 1
(A) Pulse sequence diagram illustrating the ME-GRE sequence with the navigator incorporated before the first echo of each echo series. (B) ME-GRE pipeline of navigator-based correction in the spinal cord. Raw data was converted to image space using a 1D fast Fourier transform. Static phase contributions were removed, and dynamic B0聽fluctuations were isolated by phase normalization. Within each slice, an SNR-weighted averaging across coils was computed. Finally, using the center phase value of the combined navigator signal, the expected phase accrual induced by the estimated phase field-estimates was removed by demodulation, producing the navigator-reconstructed image.