MRI Able to Detect Changes in Disc Fluid Content

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MRI Able to Detect Changes in Disc Fluid Content

Intervertebral discs (IVDs) cushion the load between adjacent vertebrae while maintaining the mechanical coupling between vertebrae. The daily cycle of erect and supine posture results in large changes in load which may affect the fluid volume in the IVDs.

Five healthy subjects participated in a study that used magnetic resonance imaging (MRI) to measure volume changes in the lumbar IVDs during a load cycle. The load cycle, designed to simulate an average daily load pattern, consisted of bedrest, followed by walking with a 20 kilogram backpack for three hours, then bedrest for three hours.
MRI scans of the lumbar spine were obtained 10 times during the load cycle, and disc volume was calculated by summing the disc area contained in each slice of the scan.
Conclusions: Load-induced changes in disc volume can be detected and measured using MRI. Disc volume increased by an average of 5.4% three hours after removing the compressive load - meaning that, assuming the average water content of the disc nucleus and annulus to be 75%, the disc gained approximately 7% of its fluid under load.
This is an intriguing, well-organized paper; it may also be the first paper to report measuring fluid changes in the intervertebral discs of live subjects during different states of spinal loading.
Malko JA, Hutton WC, Fajman WA. An in vivo magnetic resonance imaging study of changes in the volume (and fluid content) of the lumbar intervertebral discs during a simulated diurnal load cycle. Spine, May 15, 1999:24(10), pp1015-1022.