Postural changes of the dural sac in the lumbar spines of asymptomatic individuals using positional stand-up magnetic resonance imaging.

Study Design.Positional magnetic resonance imaging (MRI) study of control subjects.Objectives.To determine dimensional changes in the lumbar dural sac as a function of posture, and to establish changes between the supine, erect and seated positions.Summary of Background Data.Studies using computeriz