Dynamic analysis of lumbar spine cerebrospinal fluid flow during deep respiration using a modified time-spatial labeling inversion pulse: technical feasibility in a healthy volunteer.

Objective: The objective of this study is to investigate the lumbar cerebrospinal fluid (CSF) movement using the modified Time-Spatial Inversion Pulse (Time-SLIP) method.

Materials And Methods: This single-case experimental study was approved by the institutional ethics committee. The participant was a healthy 42-year-old male volunteer who provided written informed consent. Time-SLIP was acquired in the mid-sagittal plane and triggered every 9s. Labeling pulse was performed 4s post-trigger on four levels: Th11/L1/L3/L5 or Th12/L2/L4/S1. Subsequently, scanning commenced after 2s. During each Time-SLIP cycle, an 8-s deep-abdominal-breath cycle was repeated: (i) 1-s breath-hold, (ii) 2-s inhalation, (iii) 2-s breath-hold, (iv) 2-s exhalation, and (v) 1-s breath-hold. By shifting the Time-SLIP and breathing cycles, CSF movement was observable across all respiratory phases within 72s-the least common multiple of 9s (Time-SLIP) and 8s (deep-abdominal-breath). Moreover, Time-SLIP was maintained for 216s, and the 72-s images acquired during a stabilized respiratory cycle were extracted and compared with the labeling images to measure the movement distance. These experiments were conducted nine times over 3days.

Results: The CSF moved toward the cranial side during inhalation and toward the caudal side during exhalation. Furthermore, the range of movement during deep breathing was observed, with a median of 95.6mm (interquartile range, 91.5‒112.6) at L1, 86.1 (71.3‒99.8) at L2, 72.4 (61.3‒85.3) at L3, 57.7 (42.9‒62.4) at L4, 21.0 (19.5‒25.3) at L5, and 12.4 (9.6‒13.7) at S1. The labels of Th11 and Th12 extended beyond the field of view and could not be measured.

Conclusion: Respiratory-related CSF movement was observed using this clinically applicable, modified Time-SLIP method.