MRI-Based Estimation of Lumbar CSF Volume and Its Clinical Impact on Spinal Anaesthesia

This prospective observational study aims to investigate the clinical impact of lumbar cerebrospinal fluid (CSF) volume on spinal anesthesia characteristics. A total of 40 adult patients, aged 18 to 75 years and classified as ASA physical status I-III, who had undergone 3D T2-weighted lumbosacral MRI within the past six months, were enrolled. Intrathecal anesthesia was administered with 4 mL (20 mg) of 0.5% hyperbaric bupivacaine via the L3-L4 interspace in a sitting position. CSF volume was measured from the lower half of the L1 vertebral body to the sacral end using the volume of interest (VOI) method on sagittal 3D T2-weighted MR images, processed with the ITK-SNAP software. Primary outcome was the correlation between lumbosacral CSF volume and peak sensory block level. Secondary outcomes included correlations with the onset time and duration of sensory and motor block, two-segment regression time, and patient characteristics such as height, weight, BMI, and age.