Transition of the craniocaudal velocity of the spinal cord: from cervical segment to lumbar enlargement.

RATIONALE AND OBJECTIVES: The authors investigate the craniocaudal velocity of the spinal cord over its full length by using magnetic resonance imaging. METHODS: A spin-echo pulse sequence with velocity encoding gradients was used to examine five normal volunteers. Oblique-axial phase images at nine levels, from cervical spinal cord to lumbar enlargement, were obtained with prospective electrocardiogram gating. Time-velocity curves were then generated for these levels. RESULTS: Every part of the spinal cord moves first caudally after the R-wave of the electrocardiogram, then cranially. When compared with the cranial levels, peak velocity tend to occur later and their values tend to be smaller at the more caudal levels. CONCLUSIONS: Craniocaudal velocity is transmitted from cervical segment to lumbar enlargement.