Transurethral ultrasound applicators with dynamic multi-sector control for prostate thermal therapy: in vivo evaluation under MR guidance.
Transurethral ultrasound applicators with dynamic multi-sector control for prostate thermal therapy: in vivo evaluation under MR guidance.
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DOI：
10.1118/1.2900131
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发表时间：
2008-05
期刊：
影响因子：
3.8
通讯作者：
A. Kinsey;C. Diederich;V. Rieke;W. Nau;K. Pauly;D. Bouley;G. Sommer
中科院分区：
文献类型：
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作者：
A. Kinsey;C. Diederich;V. Rieke;W. Nau;K. Pauly;D. Bouley;G. Sommer
本研究的目的是探索用于前列腺热疗的多扇区管状阵列经尿道超声施源器的可行性和性能，该施源器有可能在MR引导下提供动态加热角度和长度控制，而无需机械移动施源器。制造测试配置，其结合两个多扇区管状换能器（7.8- 8.4MHz，3 mm OD，6 mm长度）的线性阵列，每个管具有三个120度独立的有源扇区。柔性输送导管有助于在可膨胀尿道球囊（35 mm长x 10 mm直径）内进行水冷却（100 ml min（-1））。集成的定位毂允许在尿道球囊内旋转和平移换能器组件，以在治疗递送之前进行最终靶向。旋转波束图指示来自每个120度换能器扇区的大约90度-100度声学输出图案，扇区之间的耦合可忽略，并且声学效率在41%和53%之间。在体内犬前列腺（n = 3）内进行实验，在轴向或冠状面进行实时MR温度监测，以便于控制加热曲线并提供热剂量测定用于性能评估。对暴露于TTC（氯化三苯基四氮唑）组织活力染色的经处理前列腺的连续切片进行大体检查，可直接评估热凝固的程度。这些器械产生了大的连续热损伤（由52 ℃最高温度、t43 = 240 min热剂量轮廓和TTC组织切片定义），从施用器向前列腺边缘径向延伸（约15 mm）（每个活动扇区大约8-16 W，8-15 min），根据激活方案，显示大约200度或360度扇区凝固。瞬态温度分布的分析表明，致死温度和热剂量等值线的进展最初集中在每个扇区，在大约5分钟内合并，在扇区之间产生均匀和连续的热破坏区，具有光滑的外边界和持续的径向传播。凝固区沿着施源器的尺寸通过定位和有源阵列长度明确定义。虽然不如目前正在开发的用于MR引导手术的旋转平面和曲线器械精确，但这些多扇区经尿道施源器的优点包括柔性输送导管，并且在治疗期间不需要使用旋转电机对器械进行机械操纵。这种多扇区管状阵列经尿道超声技术已经证明了相对快速和合理的前列腺体积适形靶向的潜力，适用于在MR引导下对BPH和癌症进行微创治疗，并有必要进一步发展。
The purpose of this study was to explore the feasibility and performance of a multi-sectored tubular array transurethral ultrasound applicator for prostate thermal therapy, with potential to provide dynamic angular and length control of heating under MR guidance without mechanical movement of the applicator. Test configurations were fabricated, incorporating a linear array of two multi-sectored tubular transducers (7.8-8.4 MHz, 3 mm OD, 6 mm length), with three 120 degrees independent active sectors per tube. A flexible delivery catheter facilitated water cooling (100 ml min(-1)) within an expandable urethral balloon (35 mm long x 10 mm diameter). An integrated positioning hub allows for rotating and translating the transducer assembly within the urethral balloon for final targeting prior to therapy delivery. Rotational beam plots indicate approximately 90 degrees-100 degrees acoustic output patterns from each 120 degrees transducer sector, negligible coupling between sectors, and acoustic efficiencies between 41% and 53%. Experiments were performed within in vivo canine prostate (n = 3), with real-time MR temperature monitoring in either the axial or coronal planes to facilitate control of the heating profiles and provide thermal dosimetry for performance assessment. Gross inspection of serial sections of treated prostate, exposed to TTC (triphenyl tetrazolium chloride) tissue viability stain, allowed for direct assessment of the extent of thermal coagulation. These devices created large contiguous thermal lesions (defined by 52 degrees C maximum temperature, t43 = 240 min thermal dose contours, and TTC tissue sections) that extended radially from the applicator toward the border of the prostate (approximately15 mm) during a short power application (approximately 8-16 W per active sector, 8-15 min), with approximately 200 degrees or 360 degrees sector coagulation demonstrated depending upon the activation scheme. Analysis of transient temperature profiles indicated progression of lethal temperature and thermal dose contours initially centered on each sector that coalesced within approximately 5 min to produce uniform and contiguous zones of thermal destruction between sectors, with smooth outer boundaries and continued radial propagation in time. The dimension of the coagulation zone along the applicator was well-defined by positioning and active array length. Although not as precise as rotating planar and curvilinear devices currently under development for MR-guided procedures, advantages of these multi-sectored transurethral applicators include a flexible delivery catheter and that mechanical manipulation of the device using rotational motors is not required during therapy. This multi-sectored tubular array transurethral ultrasound technology has demonstrated potential for relatively fast and reasonably conformal targeting of prostate volumes suitable for the minimally invasive treatment of BPH and cancer under MR guidance, with further development warranted.