Introduction: Diffusion-weighted MRI (DWI) is a powerful technique for evaluating spinal cord damage prior to surgery in individuals with cervical myelopathy or traumatic injuries. There is also emerging evidence that these methods may provide monitoring and/or prognostic biomarkers of post-surgical recovery; however, their application is severely limited by our current inability to obtain high-quality DWI near metal implants. This leaves surgeons with limited quantifiable metrics on which to base clinical decisions. Various approaches have been proposed to overcome these challenges, but these methods require long scans and/or yield images of reduced quality (e.g., low signal-to-noise ratio, SNR). Here we developed a new approach by incorporating several technologies (turbo spin-echo (TSE) readouts for reduced distortion, reduced field-of-view (rFOV) imaging for shorter scans, and multi-spectral imaging (MSI) for reduced metal artifacts) to yield high-quality DWI images near metal implants within clinically viable scan times. Herein, we evaluated our new technique, TSE-MSI to determine if it has the potential to improve image quality in patients with metal implants.
Methods: Our novel technique was evaluated on healthy volunteers with several staples padded/taped to the neck to simulate the metal artifacts in a controlled manner; and a cervical myelopathy patient with metal implants from a C3-C4 anterior cervical discectomy and fusion (ACDF) procedure, whereby an anterior metal plate was affixed to the spine with four metal screws. Comparison image data were acquired for each subject using standard DWI, a recently developed PROPELLER-MSI technique (a competing method that requires longer scan times), and our proposed TSE-MSI approach, with matching resolution on a 3.0-T Philips MRI scanner.
Results: Volunteer results demonstrated that substantial signal loss/distortion of the spinal cord near the metal observed in standard DWI was recovered in both PROPELLER-MSI and TSE-MSI, while our novel TSE-MSI approach exhibited superior SNR performance. Preliminary patient results confirmed these findings. Future work will focus on evaluating this approach in a large cohort of patients with cervical myelopathy and traumatic injuries to evaluate performance across different implants.
Conclusion : TSE-MSI yielded fast, high-quality DWI near metal implants, which is not possible with current methods and may provide non-invasive biomarkers of post-surgical recovery.
