MR thermometry-guided ultrasound hyperthermia of user-defined regions using the ExAblate prostate ablation array
MR thermometry-guided ultrasound hyperthermia of user-defined regions using the ExAblate prostate ablation array
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DOI：
10.1186/s40349-018-0115-5
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发表时间：
2018-08-13
期刊：
影响因子：
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通讯作者：
Rieke, Viola
中科院分区：
文献类型：
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作者：
Ozhinsky, Eugene;Salgaonkar, Vasant A.;Rieke, Viola
背景：热疗是放疗、化疗和免疫治疗的有效辅助手段。为了安全有效地实施热疗，需要将目标组织温度维持在较窄的范围内(40-44摄氏度)30-60分钟，这就需要适形热疗和准确的温度监测。本项目的目标是开发一种基于ExAblate前列腺阵列的MR温度引导热疗传输平台，在实现对前列腺内大体积的均匀稳定加热的同时，允许用户精确控制治疗区域(ROT)的能量沉积模式和形状。方法：该平台集成了加速的多层实时MR温度测量脉冲序列和重建流水线。通过多点温度采样和多焦点反馈功率控制，实现了大面积连续区域的温度均匀。热疗传输系统基于InSightec ExAblate 2100前列腺聚焦超声消融系统，以及HeartVista的RTHawk实时核磁共振系统与3T核磁共振扫描仪集成。结果：在5×5网格(35×35 mm，每个形状11~25个焦点)上定义了5种不同的治疗区域形状，以评估系统的性能。在达到稳定状态后获得的MR温度图像显示了不同的加热模式，这些模式与指定的区域非常匹配。温度采集的温度不确定度为0.5℃。达到目标温度的时间(2：58-7：44分钟)取决于所选择的腐烂形状和传感器到焦平面的距离。结论：我们利用ExAblate前列腺阵列实现了一种实时MR温度引导系统，用于在用户定义的区域内进行热疗，并在不同形状和病灶深度的体模实验中对其进行了评估。我们的结果证明了使用商业上可用的直肠内FUS换能器进行空间适形热疗的可行性，并可能为这些设备带来一系列令人兴奋的应用。
Background: Hyperthermia therapy (HT) has shown to be an effective adjuvant to radiation, chemotherapy, and immunotherapy. In order to be safe and effective, delivery of HT requires maintenance of target tissue temperature within a narrow range (40-44 degrees C) for 30-60 min, which necessitates conformal heat delivery and accurate temperature monitoring. The goal of this project was to develop an MR thermometry-guided hyperthermia delivery platform based upon the ExAblate prostate array that would achieve uniform stable heating over large volumes within the prostate, while allowing the user to precisely control the power deposition patterns and shape of the region of treatment (ROT).Methods: The HT platform incorporates an accelerated multi-slice real time MR thermometry pulse sequence and reconstruction pipeline. Temperature uniformity over a large contiguous area was achieved by multi-point temperature sampling with multi-focal feedback power control. The hyperthermia delivery system was based on an InSightec ExAblate 2100 prostate focused ultrasound ablation system, and HeartVista's RTHawk real-time MRI system integrated with a 3 T MRI scanner. The integrated system was evaluated in experiments with a tissue-mimicking phantom for prolonged exposures with a target temperature increase of 7 degrees C from baseline.Results: Five various shapes of the region of treatment, defined on a 5 x 5 grid (35 x 35 mm, 11-25 focal spots per shape), were implemented to evaluate the performance of the system. MR temperature images, acquired after steady state was reached, showed different patterns of heating that closely matched the prescribed regions. Temperature uncertainty of the thermometry acquisition was 0.5 degrees C. The time to reach the target temperature (2: 58-7: 44 min) depended on the chosen ROT shape and on the distance from transducer to focal plane. Pre-cooling with circulating water helped to reduce near-field heating.Conclusions: We have implemented a real-time MR thermometry-guided system for hyperthermia delivery within user-defined regions with the ExAblate prostate array and evaluated it in phantom experiments for different shapes and focal depths. Our results demonstrate the feasibility of using a commercially available endorectal FUS transducer to perform spatially-conformal hyperthermia therapy and could lead to a new set of exciting applications for these devices.