MR Guidance and Thermometry of Percutaneous Laser Disc Decompression in Open MRI: An Ex Vivo Study
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To assess the feasibility of guidance and thermometry by open 1.0 T magnetic resonance (MR) imaging during percutaneous laser disc decompression (PLDD).
A fluoroscopic proton-density-weighted turbo spin echo sequence was used for positioning a laser fiber and a reference thermosensor within the targeted spinal disc. In 30 lumbar discs from human donors, nonspoiled gradient-echo (GRE) sequences with different echo times (TE) were compared to monitor thermal laser effects (Nd:YAG laser, 1,064 nm). Temperature distribution was visualized in real time on the basis of T1-weighted images and the proton resonance frequency (PRF) technique. Image quality, temperature accuracy, and correlation with macroscopic lesion sizes were analyzed. Image quality was confirmed in healthy volunteers.
MR-guided placement of the laser fiber in the center of the targeted disk was precise. Best overall PLDD results—considering image quality (contrast-to-noise ratio), temperature accuracy (R 2 = 0.96), and correlation between the macroscopic and MR lesions (R 2 = 0.63)—were achieved with TE at 7 ms. The same TE value also gave the best image quality with healthy volunteers.
Instrument guidance and PRF-based thermometry of PLDD in the lumbar spine are feasible and accurate. Open 1.0 T MR imaging with fast spin-echo and GRE sequence designs may render laser discectomies more effective and controllable.
KeywordsExperimental IR Nonvascular interventions Ablation Skeletal intervention Laser treatment Spine/nervous system Pain
We thank Virginia Ding-Reinelt and Andreas Thomas for expert MRI technical assistance. This work was supported in part by grants from the Technologiestiftung Berlin—Zukunftsfonds Berlin (TSB) and the EUs European Fund for Regional Development (Grant 10132816/10134231).
Conflict of interest
The authors declare that they have no conflict of interest.
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