MR Guidance and Thermometry of Percutaneous Laser Disc Decompression in Open MRI: An Ex Vivo Study

• Published in: Cardiovascular and interventional radiology 2014-06, Vol.37 (3), p.777-783
• Main Authors: Streitparth, Florian, Walter, Thula, Wonneberger, Uta, Schnackenburg, Bernhard, Philipp, Carsten M., Collettini, Federico, Teichgräber, Ulf K. M., Gebauer, Bernhard
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Cardiology; Decompression, Surgical; Feasibility Studies; Female; Humans; Imaging; In Vitro Techniques; Intervertebral Disc - surgery; Laboratory Investigation; Laser Therapy - methods; Magnetic Resonance Imaging - instrumentation; Magnetic Resonance Imaging, Interventional; Male; Medicine; Medicine & Public Health; Middle Aged; Nuclear Medicine; Radiology; Thermometry - methods; Treatment Outcome; Ultrasound
• ISSN: 0174-1551; 1432-086X
• DOI: 10.1007/s00270-013-0734-8

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.