MR guided thermal therapy of pancreatic tumors with endoluminal, intraluminal and interstitial catheter-based ultrasound devices: Preliminary theoretical and experimental investigations.
MR guided thermal therapy of pancreatic tumors with endoluminal, intraluminal and interstitial catheter-based ultrasound devices: Preliminary theoretical and experimental investigations.
复制标题
使用腔内、腔内和间质导管超声设备对胰腺肿瘤进行 MR 引导热治疗：初步理论和实验研究。
DOI：
10.1117/12.2004669
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Diederich,ChrisJ
中科院分区：
文献类型：
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作者：
Prakash,Punit;Salgaonkar,VasantA;Scott,SerenaJ;Jones,Peter;Hensley,Daniel;Holbrook,Andrew;Plata,Juan;Sommer,Graham;Diederich,ChrisJ
图像引导的热干预已被提出用于胰腺肿瘤的潜在姑息性和根治性治疗。基于导管的超声设备为能量沉积剖面的时间和三维空间控制提供了可能性。本研究的目的是应用理论和实验技术，探讨胃内、腔内和经胃导管超声在MR引导下热疗胰腺肿瘤中的可行性。经胃入路包括通过内窥镜或通过图像引导经皮放置，将基于导管的超声辐射器(1.5 mm外径x 10 mm换能器阵列，360°或扇形180°，~7 MHz频率，13-14G冷却导管)直接插入胰腺。腔内敷贴器具有更灵活但相似的结构，可考虑在内窥镜下直接插入胰腺或胆管。腔内入路是基于封装在冷却气球中的超声换能器组件(管状、平面、曲线)，该冷却气球在内窥镜下定位在胃或十二指肠内，从胃肠道内毗邻胰腺靶点。建立了三维声学生物热模型来计算声能分布，并使用有限元解算器确定了加热过程中组织中的瞬时温度和热剂量分布。这些模型被用来确定换能器参数和输送策略，并研究在保留胃壁的情况下，消融位于胰腺2-10 mm深、直径1-3 cm的肿瘤的可行性。不同的声学和热学特性被结合在一起，包括对肿瘤结缔组织发育和加热过程中动态变化的近似。一系列基于典型患者影像扫描的解剖模型被用来研究这三种入路。概念验证(POC)在多层磁共振测温下，在模拟体模、活体组织和活体组织模型中制作了胃内和胃内敷贴器，并对其进行了实验评估。对射频微线圈进行评估，以实现主动导管跟踪和温度测量切片位置的处方。当超声功率为20~30W/cm~2，频率为7 MHz，作用时间为5~10min时，腔内和间质超声可用于治疗直径2.3~3.4 cm的肿瘤(T43>；240min)。带平面和曲线探头的腔内敷贴器工作频率为3~4 MHz，可在5分钟内治疗距胃壁20~25 mm的肿瘤。制作了POC设备，并成功地将其集成到MRI环境中，实现了导管跟踪、实时测温和闭环反馈控制。
Image-guided thermal interventions have been proposed for potential palliative and curative treatments of pancreatic tumors. Catheter-based ultrasound devices offer the potential for temporal and 3D spatial control of the energy deposition profile. The objective of this study was to apply theoretical and experimental techniques to investigate the feasibility of endogastric, intraluminal and transgastric catheter-based ultrasound for MR guided thermal therapy of pancreatic tumors. The transgastric approach involves insertion of a catheter-based ultrasound applicator (array of 1.5 mm OD x 10 mm transducers, 360° or sectored 180°, ~7 MHz frequency, 13-14G cooling catheter) directly into the pancreas, either endoscopically or via image-guided percutaneous placement. An intraluminal applicator, of a more flexible but similar construct, was considered for endoscopic insertion directly into the pancreatic or biliary duct. An endoluminal approach was devised based on an ultrasound transducer assembly (tubular, planar, curvilinear) enclosed in a cooling balloon which is endoscopically positioned within the stomach or duodenum, adjacent to pancreatic targets from within the GI tract. A 3D acoustic bio-thermal model was implemented to calculate acoustic energy distributions and used a FEM solver to determine the transient temperature and thermal dose profiles in tissue during heating. These models were used to determine transducer parameters and delivery strategies and to study the feasibility of ablating 1-3 cm diameter tumors located 2-10 mm deep in the pancreas, while thermally sparing the stomach wall. Heterogeneous acoustic and thermal properties were incorporated, including approximations for tumor desmoplasia and dynamic changes during heating. A series of anatomic models based on imaging scans of representative patients were used to investigate the three approaches. Proof of concept (POC) endogastric and transgastric applicators were fabricated and experimentally evaluated in tissue mimicking phantoms,ex vivotissue andin vivocanine model under multi-slice MR thermometry. RF micro-coils were evaluated to enable active catheter-tracking and prescription of thermometry slice positions. Interstitial and intraluminal ultrasound applicators could be used to ablate (t43>240min) tumors measuring 2.3-3.4 cm in diameter when powered with 20-30 W/cm2at 7 MHz for 5-10 min. Endoluminal applicators with planar and curvilinear transducers operating at 3-4 MHz could be used to treat tumors up to 20-25 mm deep from the stomach wall within 5 min. POC devices were fabricated and successfully integrated into the MRI environment with catheter tracking, real-time thermometry and closed-loop feedback control.