PERCUTANEOUS LASER DISKECTOMY - MR FINDINGS WITHIN THE FIRST 24 HOURSAFTER TREATMENT AND THEIR RELATIONSHIP TO CLINICAL OUTCOME

Objective: The purpose of this study was to evaluate the early MR appe arances of the intervertebral disc obtained within 24 h after percutan eous laser discectomy and to determine if a correlation exists between the MR images and the clinical outcome. Subjects and Methods: Twenty- nine discs in 26 patients with contained lumbar disc herniation treate d by laser were included, Laser intervention was performed using Ho:YA G laser system, The results were quantitatively analysed by measuring areal changes of the herniated mass on axial T1-weighted images and si gnal changes within the disc on sagittal T2-weighted images, Clinical outcomes were evaluated according to Japanese Orthopaedic Association score (JOA score), and recovery rates based on JOA score immediately a nd 1 year after treatment were calculated. Results: The recovery rate immediately after treatment was 53.1%, and increasing to 64.6% 1 year later, The size of the disc herniation ranged from 7% to 55% of the ax ial cross-section of the spinal canal pre-operatively and no significa nt changes were noted postoperatively. Also no correlation was found b etween the pre-operative herniation size and the recovery rate, The si gnal changes within the disc increased significantly after treatment, but no correlation was present between the signal changes and the reco very rate, In five patients, soft-tissue changes along the laser tract were well demonstrated on MR imaging. Conclusion: Although immediate postoperative MR imaging shows early tissue changes induced by laser, our study has not proven that immediate postoperative MR imaging could predict the clinical outcome after percutaneous laser discectomy.