An in vivo MRI study of the changes in volume (and fluid content) of the lumbar intervertebral disc after overnight bed rest and during an 8-hour walking protocol

Summary: Magnetic resonance imaging (MRI) was used to measure the changes in the volume (and fluid content) of the lumbar intervertebral discs (L1–L2, L2–L3, L3–L4, L4–L5) in five normal subjects. For each subject, MRI scans were taken at the end of a normal day and again on the following morning (after a night's bed rest). Ten further scans were taken during an 8-h protocol consisting of alternate periods of walking (40 min) and scanning (10 min). On average, 1) disc volume increased by 10.6% during overnight bed rest, which corresponds to a gain of about 0.9 cm3 of fluid; 2) the rate of disc volume decrease during the 8-h walking protocol was 0.96 × 10−3 cm3/min; and 3) after 8 h (using our walking/scanning protocol), the disc volume did not decrease to the volume measured at the end of the previous day.