MRI Atlas-Based Measurement of Spinal Cord Injury Predicts Outcome in Acute Flaccid Myelitis

Editor’s Choice

Using the open source platform, the “Spinal Cord Toolbox,” the authors sought to correlate measures of GM, WM, and cross-sectional area pathology on T2 MR imaging with motor disability in 9 patients with acute flaccid myelitis. Proportion of GM metrics at the center axial section significantly correlated with measures of motor impairment upon admission and at 3-month follow-up. The proportion of GM extracted across the full lesion segment significantly correlated with initial motor impairment. This is the first atlas-based study to correlate clinical outcomes with segmented measures of T2 signal abnormality in the spinal cord.

Abstract

Figure 1 from paper
Steps for registering patient 5 (acute flaccid paralysis) to template. A, Red circles indicate manual marking of anatomic features C1 and C8. Blue lines indicate axial sections illustrated in far right grid. B, Manual masking of SC centerline was done at each axial section because of signal hyperintensity interfering with automatic reconstruction of centerline. C, MNI-Poly-AMU T2-weighted template. D, SC straightening using thin-plate spline interpolation. E, Labeling of vertebral levels after registering to template and warping back to native space. F, Sagittal view of GM and WM probabilistic atlas after registering to template and warping back to native space. Far right grid, Output of template-based atlas. Column 1, Automatic vertebral body labeling and SC space. Column 2, Probabilistic masks of WM. Column 3, Probabilistic masks of GM. Column 4, Probabilistic masks of GM and WM overlaid.

BACKGROUND AND PURPOSE

Recent advances in spinal cord imaging analysis have led to the development of a robust anatomic template and atlas incorporated into an open-source platform referred to as the Spinal Cord Toolbox. Using the Spinal Cord Toolbox, we sought to correlate measures of GM, WM, and cross-sectional area pathology on T2 MR imaging with motor disability in patients with acute flaccid myelitis.

MATERIALS AND METHODS

Spinal cord imaging for 9 patients with acute flaccid myelitis was analyzed by using the Spinal Cord Toolbox. A semiautomated pipeline using the Spinal Cord Toolbox measured lesion involvement in GM, WM, and total spinal cord cross-sectional area. Proportions of GM, WM, and cross-sectional area affected by T2 hyperintensity were calculated across 3 ROIs: 1) center axial section of lesion; 2) full lesion segment; and 3) full cord atlas volume. Spearman rank order correlation was calculated to compare MR metrics with clinical measures of disability.

RESULTS

Proportion of GM metrics at the center axial section significantly correlated with measures of motor impairment upon admission (r [9] = −0.78; P = .014) and at 3-month follow-up (r [9] = −0.66; P = .05). Further, proportion of GM extracted across the full lesion segment significantly correlated with initial motor impairment (r [9] = −0.74, P = .024). No significant correlation was found for proportion of WM or proportion of cross-sectional area with clinical disability.

CONCLUSIONS

Atlas-based measures of proportion of GM T2 signal abnormality measured on a single axial MR imaging section and across the full lesion segment correlate with motor impairment and outcome in patients with acute flaccid myelitis. This is the first atlas-based study to correlate clinical outcomes with segmented measures of T2 signal abnormality in the spinal cord.

 

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MRI Atlas-Based Measurement of Spinal Cord Injury Predicts Outcome in Acute Flaccid Myelitis
jross
Jeffrey Ross • Mayo Clinic, Phoenix

Dr. Jeffrey S. Ross is a Professor of Radiology at the Mayo Clinic College of Medicine, and practices neuroradiology at the Mayo Clinic in Phoenix, Arizona. His publications include over 100 peer-reviewed articles, nearly 60 non-refereed articles, 33 book chapters, and 10 books. He was an AJNR Senior Editor from 2006-2015, is a member of the editorial board for 3 other journals, and a manuscript reviewer for 10 journals. He became Editor-in-Chief of the AJNR in July 2015. He received the Gold Medal Award from the ASSR in 2013.

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