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Erschienen in:
01.06.2014 | Laboratory Investigation
MR Guidance and Thermometry of Percutaneous Laser Disc Decompression in Open MRI: An Ex Vivo Study
Erschienen in: CardioVascular and Interventional Radiology | Ausgabe 3/2014
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Purpose
To assess the feasibility of guidance and thermometry by open 1.0 T magnetic resonance (MR) imaging during percutaneous laser disc decompression (PLDD).
Methods
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.
Results
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.
Conclusion
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.