Metal artifact reduction around cervical spine implant using diffusion tensor imaging at 3T: A phantom study

Slimane Tounekti; Mahdi Alizadeh; Devon Middleton; James S Harrop; Bassem Hiba; Laura Krisa; Choukri Mekkaoui; Feroze B Mohamed

doi:10.1016/j.mri.2023.11.007

Metal artifact reduction around cervical spine implant using diffusion tensor imaging at 3T: A phantom study

Magn Reson Imaging. 2024 Jan:105:57-66. doi: 10.1016/j.mri.2023.11.007. Epub 2023 Nov 7.

Authors

Slimane Tounekti¹, Mahdi Alizadeh², Devon Middleton³, James S Harrop², Bassem Hiba⁴, Laura Krisa⁵, Choukri Mekkaoui⁶, Feroze B Mohamed³

Affiliations

¹ Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA. Electronic address: Slimane.tounekti@jefferson.edu.
² Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA, USA.
³ Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA.
⁴ Institut des Sciences Cognitives, CNRS UMR 5229, Université Lyon 1, Lyon, France.
⁵ Department of Physical Therapy, Thomas Jefferson University, Philadelphia, PA, USA.
⁶ Harvard Medical School, Boston, MA, USA; Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; A.A. Martinos Center for Biomedical Imaging, Charlestown, MA, USA.

PMID: 37939969
PMCID: PMC10841892 (available on 2025-01-01)
DOI: 10.1016/j.mri.2023.11.007

Abstract

Purpose: Diffusion MRI continues to play a key role in non-invasively assessing spinal cord integrity and pre-operative injury evaluation. However, post-operative Diffusion Tensor Imaging (DTI) acquisition of patients with metal implants results in severe geometric distortion. We propose and demonstrate a method to alleviate the technical challenges facing the acquisition of DTI on post-operative cases and longitudinal evaluation of therapeutics.

Material and methods: The described technique is based on the combination of the reduced Field-Of-View (rFOV) strategy and the phase segmented EPI, termed rFOV-PS-EPI. A custom-built phantom based on a cervical spine model with metal implants was used to collect DTI data at 3 Tesla scanner using: rFOV-PS-EPI, reduced Field-Of-View single-shot EPI (rFOV-SS-EPI), and conventional full FOV techniques including SS-EPI, PS-EPI, and readout-segmented EPI (RS-EPI). Geometric distortion, SNR, and signal void were assessed to evaluate images and compare the sequences. A two-sample t-test was performed with p-value of 0.05 or less to indicate statistical significance.

Results: The reduced FOV techniques showed better capability to reduce distortions compared to the Full FOV techniques. The rFOV-PS-EPI method provided DTI images of the phantom at the level of the hardware whereas the conventional rFOV-SS-EPI is useful only when the metal is approximately 20 mm away. In addition, compared to the rFOV-SS-EPI technique, the suggested approach produced smaller signal voids area as well as significantly reduced geometric distortion in Circularity (p < 0.005) and Eccentricity (p < 0.005) measurements. No statistically significant differences were found for these geometric distortion measurements between the rFOV-PS-EPI DTI sequence and conventional structural T2 images (p > 0.05).

Conclusion: The combination of rFOV and a phase-segmented acquisition approach is effective for reducing metal-induced distortions in DTI scan on spinal cord with metal hardware at 3 T.

Keywords: 3 Tesla; Diffusion tensor imaging; Geometric distortion; Metal artifacts; Metal implant.

MeSH terms

Artifacts*
Cervical Vertebrae / diagnostic imaging
Cervical Vertebrae / surgery
Diffusion Magnetic Resonance Imaging / methods
Diffusion Tensor Imaging* / methods
Echo-Planar Imaging / methods
Humans
Spinal Cord

Grants and funding

R01 NS111113/NS/NINDS NIH HHS/United States