Wolfram Frank, Dietrich Georg, Boltze Carsten, Jenderka Klaus Vitold, Lesser Thomas Günther
Department of Thoracic and Vascular Surgery, SRH Wald-Klinikum Gera, Teaching Hospital of Friedrich-Schiller University of Jena, Gera, Germany.
Gampt Ultrasonic Solutions mbH, Merseburg, Germany.
J Ther Ultrasound. 2017 Aug 7;5:21. doi: 10.1186/s40349-017-0099-6. eCollection 2017.
High intensity focused ultrasound (HIFU) has gained clinical interest as a non-invasive local tumour therapy in many organs. In addition, it has been shown that lung cancer can be targeted by HIFU using One-Lung Flooding (OLF). OLF generates a gas free saline-lung compound in one lung wing and therefore acoustic access to central lung tumours. It can be assumed that lung parenchyma is exposed to ultrasound intensities in the pre-focal path and in cases of misguiding. If so, cavitation might be induced in the saline fraction of flooded lung and cause tissue damage. Therefore this study was aimed to determine the thresholds of HIFU induced cavitation and tissue erosion in flooded lung.
Resected human lung lobes were flooded ex-vivo. HIFU (1,1 MHz) was targeted under sonographic guidance into flooded lung parenchyma. Cavitation events were counted using subharmonic passive cavitation detection (PCD). B-Mode imaging was used to detect cavitation and erosion sonographically. Tissue samples out of the focal zone were analysed histologically.
In flooded lung, a PCD and a sonographic cavitation detection threshold of 625 ( = 4, 3 ) and 3.600 ( = 8, 3 ) was found. Cavitation in flooded lung appears as blurred hyperechoic focal region, which enhances echogenity with insonation time. Lung parenchyma erosion was detected at intensities above 7.200 ( = 10, 9 ).
Cavitation occurs in flooded lung parenchyma, which can be detected passively and by B-Mode imaging. Focal intensities required for lung tumour ablation are below levels where erosive events occur. Therefore focal cavitation events can be monitored and potential risk from tissue erosion in flooded lung avoided.
高强度聚焦超声（HIFU）作为一种用于许多器官的非侵入性局部肿瘤治疗方法，已引起临床关注。此外，已有研究表明，采用单肺灌注（OLF）时，HIFU可靶向治疗肺癌。OLF可在一侧肺叶中生成无气的盐水 - 肺复合物，从而实现对中央型肺肿瘤的声学通路。可以推测，在聚焦前路径以及出现误引导的情况下，肺实质会暴露于超声强度之下。如果是这样，灌注肺中的盐水部分可能会引发空化并导致组织损伤。因此，本研究旨在确定HIFU在灌注肺中引发空化和组织侵蚀的阈值。
对切除的人肺叶进行体外灌注。在超声引导下将HIFU（1.1MHz）靶向至灌注的肺实质。使用次谐波被动空化检测（PCD）对空化事件进行计数。采用B超成像在超声下检测空化和侵蚀情况。对焦点区域的组织样本进行组织学分析。
在灌注肺中，PCD检测到的空化阈值为625（ = 4, 3），超声检测到的空化阈值为3600（ = 8, 3）。灌注肺中的空化表现为模糊的高回声焦点区域，随着照射时间的延长，回声增强。在强度高于7200（ = 10, 9）时检测到肺实质侵蚀。
灌注肺实质中会发生空化，可通过被动检测和B超成像进行检测。肺肿瘤消融所需的焦点强度低于发生侵蚀事件的水平。因此，可以监测焦点空化事件，并避免灌注肺中组织侵蚀带来的潜在风险。
