Oscillatory motion of the normal cervical spinal cord.

Purpose: To determine the normal pattern of cervical spinal cord motion with measurement of cervical spinal cord velocity by means of phase-contrast magnetic resonance (MR) imaging.

Materials And Methods: Spinal cord velocity was measured in 11 healthy subjects with a modified gradient-echo pulse sequence on a conventional 1.5-T MR imaging system that generated phase images sensitive to slow motion. Prospective electrocardiogram gating was used to assess velocity as a function of the cardiac cycle. The accuracy of velocity measurements was estimated with images of a phantom moving at constant velocity.

Results: The cervical spinal cord moves with an oscillatory pattern in the craniocaudal direction. The maximum velocity (7.0 mm/sec +/- 1.4 [standard deviation]) in the caudal direction occurred approximately 109 msec +/- 20 after electrical cardiac systole. The maximum velocities in subsequent oscillations decreased toward zero before the next cardiac systole.

Conclusion: The cervical spinal cord oscillates in a craniocaudal direction after each cardiac systole.