The spinal vacuum phenomenon: evaluation by gradient echo MR imaging.

To evaluate the ability of gradient echo MR to define the vacuum phenomena, 14 cadaveric lumbar spines were imaged by spin echo and gradient echo MR, CT, and plain radiography following injection of varying amounts of air into the intervertebral disks. Gradient echo MR was more sensitive than spin echo MR or plain radiography in detecting the intradiskal gas collections as small as 0.1 cc. Computed tomography was a sensitive as gradient echo MR. Plain radiography was the least sensitive modality. Increasing the echo time of the gradient echo technique increased the conspicuity of the gas collections due to magnetic susceptibility effects.