PURPOSE Evaluation of MR feasibility and real-time control of an innovative thermoablative applicator for intradiscal thermotherapy and histological analysis of laser annuloplasty in human ex vivo intervertebral discs. MATERIALS AND METHODS We evaluated a new MR-compatible applicator system for MR-guided percutaneous intradiscal thermotherapy (MRgPIT) in an open 1.0-T MRI-system. Needle artefacts and contrast-to-noise ratios (CNR) of six interactive sequences (PD-, T1-, T2w TSE, T1-, T2w GRE, bSSFP) with varying echo-times (TE) and needle orientations to the main magnetic field (B0) were analysed. Additionally, five laser protocols (Nd: YAG Laser, 2-6 W) were assessed in 50 ex vivo human intervertebral discs with subsequent histological evaluation. RESULTS In vitro, we found optimal needle artefacts of 1.5-5 mm for the PDw TSE sequence in all angles of the applicator system to B0. A TE of 20 ms yielded the best CNR. Ex vivo, ablating with 5 W induced histological denaturation of collagen at the dorsal annulus, correlating with a rise in temperature to at least 60 °C. The MRgPIT procedure was feasible with an average intervention time of 17.1 ± 5.7 min. CONCLUSION Real-time MR-guided positioning of the MRgPIT-applicator in cadaveric intervertebral disc is feasible and precise using fast TSE sequence designs. Laser-induced denaturation of collagen in the dorsal annulus fibrosus proved to be accurate.

中文翻译：

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MR引导的经皮椎间盘内热疗（MRgPIT）：评估尸体腰椎退行性椎间盘疾病新技术的评估。

目的评估用于椎间盘内热疗法的创新型热消融涂药器的MR可行性和实时控制以及人离体椎间盘间激光瓣环成形术的组织学分析。材料和方法我们评估了一种新的MR兼容涂药器系统，该系统在开放的1.0-T MRI系统中用于MR引导的经皮椎间盘内热疗（MRgPIT）。六个交互序列（PD-，T1-，T2w TSE，T1-，T2w GRE，bSSFP）的针假象和对比噪声比（CNR），且回波时间（TE）和针指向主磁场的方向各不相同（B0）进行了分析。另外，在50个离体人椎间盘中评估了五种激光方案（Nd：YAG激光，2-6 W），随后进行了组织学评估。结果在体外，我们发现最佳的人工伪像为1。PDw TSE序列在B0的所有角度上为5-5 mm。20 ms的TE产生最佳的CNR。离体，用5 W烧蚀可引起背环的胶原组织变性，与温度升高至至少60°C相关。MRgPIT程序可行，平均干预时间为17.1±5.7分钟。结论利用快速TSE序列设计，MRgPIT施放器在尸体椎间盘中的实时MR引导定位是可行和精确的。激光诱导的纤维环背胶原蛋白变性被证明是准确的。MRgPIT程序可行，平均干预时间为17.1±5.7分钟。结论使用快速TSE序列设计，在尸体椎间盘中MRgPIT-施加器的实时MR引导定位是可行和精确的。激光诱导的纤维环背胶原蛋白变性被证明是准确的。MRgPIT程序可行，平均干预时间为17.1±5.7分钟。结论利用快速TSE序列设计，MRgPIT施放器在尸体椎间盘中的实时MR引导定位是可行和精确的。激光诱导的纤维环背胶原蛋白变性被证明是准确的。