Direct Observation of Dynamic Cerebrospinal Fluid Flow Velocity in the Lumbar Spinal Canal During Deep Respiration Using a Modified Time‐Spatial Labeling Inversion Pulse Technique

BACKGROUND: A previous single-case study has demonstrated that a modified time-spatial labeling inversion pulse (Time-SLIP) technique, specifically Deep Abdominal Breathing-induced CSF Flow Imaging with Time-SLIP (DAB Time-SLIP), successfully visualized dynamic cerebrospinal fluid (CSF) flow during deep breathing with superior contrast compared to conventional Time-SLIP. However, it is unclear whether this occurs consistently across healthy individuals. PURPOSE: To investigate CSF flow dynamics during deep breathing in healthy volunteers with the DAB Time-SLIP. STUDY TYPE: Prospective. POPULATION: 10 healthy participants (7 men; mean age, 29.5 years). FIELD STRENGTH/SEQUENCE: 1.5-Tesla, Time-SLIP. ASSESSMENT: Midsagittal Time-SLIP imaging was performed using a 9 s repetition interval. A labeling pulse was applied at four vertebral levels (Th11-L1-L3-L5 or Th12-L2-L4-S1), and images were acquired after a 2 s delay. Separate imaging sessions were conducted during shallow breathing and during a structured 8 s deep abdominal breathing cycle. During deep-abdominal-breathing, an intentional phase shift between the 9 s imaging interval and the 8 s respiratory cycle enabled visualization of CSF movement across the entire cycle within 72 s. This protocol for CSF dynamics during deep-breathing was designated as DAB Time-SLIP. Images acquired under these two breathing conditions were compared with the reference label images obtained during breath-holding, and CSF flow velocity and displacement range were quantified based on the resulting positional changes. STATISTICAL TESTS: Wilcoxon signed-rank test and simple linear regression analysis. A p < 0.05 was considered significant. RESULTS: Cranial flow occurred during inhalation, whereas caudal flow was observed during exhalation. Both the magnitude and the displacement range of CSF flow velocity and CSF movement of range progressively decreased toward the caudal direction (rS = -0.9479). Compared with free breathing, the range of CSF movement using DAB Time-SLIP was significantly greater. DATA CONCLUSION: DAB Time-SLIP demonstrated cranial CSF flow during deep inspiration and caudal CSF flow during deep expiration. TECHNICAL EFFICACY: Stage 1.