Snake-Eyes Appearance on MRI Occurs during the Late Stage of Hirayama Disease and Indicates Poor Prognosis

Figure 1

Typical SEA and measurement method on MRI. (a) On the sagittal T2-weighted MRI, the SEA showed a high signal in the middle of the spinal cord. (b) On the axial image, a typical SEA was characterized as a symmetrical, bilateral, small high-signal-intensity lesion. (c) Measurement of anteroposterior diameter (APD) on the sagittal image: APD is the distance between the anterior and the posterior edge of the spinal cord on the mid-disc line. (d) Measurement of spinal cord anterior shifting on the axial image: the distance between the posterior wall of the spinal canal and the posterior/anterior edge of the cervical spinal cord was termed A/B. Then, the ratio of A to B was used as an indicator of anterior shifting.

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