MR imaging of Ho:YAG laser diskectomy with histologic correlation.
Twelve cadaveric vertebral specimens were imaged after holmium yttrium aluminum garnet (Ho:YAG) laser diskectomy to determine the usefulness of magnetic resonance (MR) imaging in evaluating treatment outcome. The Ho:YAG laser was operated at 1.0-2.0 J per pulse, 5 Hz, and 250-microseconds pulse width. The total energy varied between 600 and 2,700 J. Two distinct patterns emerged on MR images. Tissue ablation at higher power (1.5 and 2.0 J per pulse) produced discrete signal voids that correlated with areas of laser-induced ablation identified at gross inspection. More subtle changes, characterized by a high-signal-intensity ring, were seen in the specimens lased at 1.0 J per pulse. The latter appearance corresponded to incomplete vaporization of diskal tissue, a broader zone of minimal thermal injury, and sparing of adjacent vertebral endplates. Total mass loss did not appear to be affected by the choice of power setting (1.0 vs 1.5 J per pulse), with total laser energy held constant.
Phillips
J J
JJ
Department of Radiology, Harbor-University of California, Torrance 90509.
Kopchok
G E
GE
Peng
S K
SK
Mueller
M P
MP
White
R A
RA
D000328:Adult; D000368:Aged; D006801:Humans; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000473:pathology / Q000601:surgery*; D053685:Laser Therapy / Q000295:instrumentation; D008279:Magnetic Resonance Imaging; D008875:Middle Aged