Abstract：
OBJECTIVE: MRI-guided laser interstitial thermal therapy (MRgLITT) has recently gained interest as an ablative stereotactic procedure for intractable epilepsy, movement disorders, and brain tumors. Conventionally, a LITT system consists of a laser generator and cooled laser applicator, which is a fiber optic core surrounded by a sheath through which cooled fluid is pumped. However, this footprint can make the system bulky and nonmobile, limit the maximum depth of targeting, and increase the chances of breakdown. Herein, the authors conduct a preclinical assessment of a noncooled MRgLITT system in a porcine model.
METHODS: Three-tesla MRI was used to guide the in vivo placement of noncooled laser applicators in the porcine brain. The study consisted of a survival arm and terminal arm. The laser was activated at a power of 4-7 W for ≤ 180 seconds. Temperature changes were monitored using the MR thermometry software ThermoGuide in the survival arm (n = 5) or both ThermoGuide software and adjacently inserted thermal probes in the terminal arm (n = 3). Thermal damage was determined by the software using the temperature-time relationship of cumulative equivalent minutes at 43°C (CEM43). Temperatures calculated by the software were compared with those recorded by the temperature probes. The dimensions of thermal damage thresholds (TDTs; 2-9, 10-59, 60-239, ≥ 240 CEM43 isolines) given by MR thermometry were compared with the dimensions of irreversible damage on histopathological analysis.
RESULTS: There was a strong correlation between temperature recordings by ThermoGuide and those by thermal probes at both 4 mm (r = 0.96) and 8 mm (r = 0.80), with a mean absolute error of 0.76°C ± 2.13°C and 0.17°C ± 1.65°C at 4 and 8 mm, respectively. The area of 2-9 CEM43 was larger than the area of irreversible damage seen on histopathological analysis. The dimensions of the 10 and 60 CEM43 correlated well with dimensions of the lesion on histopathological analysis. A well-defined border (≤ 1 mm) was observed between the area of irreversible damage and healthy brain tissue.
CONCLUSIONS: This preclinical assessment showed that the noncooled LITT system was able to precisely reach the target and create well-defined lesions within a margin of safety, without any adverse effects. MR thermometry software provided an accurate near-real-time temperature of the brain tissue, and dimensions of the lesion as visualized by the software correlated well with histopathological findings. Further studies to test the system\'s efficacy and safety in human subjects are in progress.
METHODS: Three-tesla MRI was used to guide the in vivo placement of noncooled laser applicators in the porcine brain. The study consisted of a survival arm and terminal arm. The laser was activated at a power of 4-7 W for ≤ 180 seconds. Temperature changes were monitored using the MR thermometry software ThermoGuide in the survival arm (n = 5) or both ThermoGuide software and adjacently inserted thermal probes in the terminal arm (n = 3). Thermal damage was determined by the software using the temperature-time relationship of cumulative equivalent minutes at 43°C (CEM43). Temperatures calculated by the software were compared with those recorded by the temperature probes. The dimensions of thermal damage thresholds (TDTs; 2-9, 10-59, 60-239, ≥ 240 CEM43 isolines) given by MR thermometry were compared with the dimensions of irreversible damage on histopathological analysis.
RESULTS: There was a strong correlation between temperature recordings by ThermoGuide and those by thermal probes at both 4 mm (r = 0.96) and 8 mm (r = 0.80), with a mean absolute error of 0.76°C ± 2.13°C and 0.17°C ± 1.65°C at 4 and 8 mm, respectively. The area of 2-9 CEM43 was larger than the area of irreversible damage seen on histopathological analysis. The dimensions of the 10 and 60 CEM43 correlated well with dimensions of the lesion on histopathological analysis. A well-defined border (≤ 1 mm) was observed between the area of irreversible damage and healthy brain tissue.
CONCLUSIONS: This preclinical assessment showed that the noncooled LITT system was able to precisely reach the target and create well-defined lesions within a margin of safety, without any adverse effects. MR thermometry software provided an accurate near-real-time temperature of the brain tissue, and dimensions of the lesion as visualized by the software correlated well with histopathological findings. Further studies to test the system\'s efficacy and safety in human subjects are in progress.
摘要：
目的：MRI引导的激光间质热治疗（MRgLITT）作为难治性癫痫的消融性立体定向手术最近引起了人们的兴趣，运动障碍,和脑肿瘤。传统上,LITT系统由激光发生器和冷却激光照射器组成，它是一个由护套包围的光纤芯，冷却流体通过护套被泵送。然而,这种占用空间会使系统笨重且不可移动，限制最大瞄准深度，并增加崩溃的机会。在这里，作者在猪模型中对非冷却MRgLITT系统进行了临床前评估.
方法：使用三特斯拉MRI指导非冷却激光施加器在猪大脑中的体内放置。该研究由存活臂和末端臂组成。在4-7W的功率下激活激光器≤180秒。使用生存臂中的MR测温软件ThermoGuide（n=5）或终端臂中的ThermoGuide软件和相邻插入的热探针（n=3）监测温度变化。通过软件使用43°C下累积等效分钟的温度-时间关系(CEM43)来确定热损伤。将软件计算的温度与温度探针记录的温度进行比较。在组织病理学分析中，将MR测温法给出的热损伤阈值（TDT；2-9、10-59、60-239，≥240CEM43等值线）的尺寸与不可逆损伤的尺寸进行了比较。
结果：TherewasastrongcorrelationbetweentemperaturerecordingsbyThermalGuideandthosebythermalprobeattoth4mm(r=0.96)and8mm(r=0.80),4和8mm处的平均绝对误差为0.76°C±2.13°C和0.17°C±1.65°C，分别。2-9CEM43的面积大于在组织病理学分析上看到的不可逆损伤的面积。在组织病理学分析中，10和60CEM43的尺寸与病变的尺寸密切相关。在不可逆损伤区域和健康脑组织之间观察到明确的边界(≤1mm)。
结论：这项临床前评估表明，非冷却LITT系统能够精确地达到目标，并在安全范围内形成明确定义的病变，没有任何不良影响。MR测温软件提供了精确的接近实时的脑组织温度，通过软件可视化的病变尺寸与组织病理学结果密切相关。测试该系统在人类受试者中的有效性和安全性的进一步研究正在进行中。
方法：使用三特斯拉MRI指导非冷却激光施加器在猪大脑中的体内放置。该研究由存活臂和末端臂组成。在4-7W的功率下激活激光器≤180秒。使用生存臂中的MR测温软件ThermoGuide（n=5）或终端臂中的ThermoGuide软件和相邻插入的热探针（n=3）监测温度变化。通过软件使用43°C下累积等效分钟的温度-时间关系(CEM43)来确定热损伤。将软件计算的温度与温度探针记录的温度进行比较。在组织病理学分析中，将MR测温法给出的热损伤阈值（TDT；2-9、10-59、60-239，≥240CEM43等值线）的尺寸与不可逆损伤的尺寸进行了比较。
结果：TherewasastrongcorrelationbetweentemperaturerecordingsbyThermalGuideandthosebythermalprobeattoth4mm(r=0.96)and8mm(r=0.80),4和8mm处的平均绝对误差为0.76°C±2.13°C和0.17°C±1.65°C，分别。2-9CEM43的面积大于在组织病理学分析上看到的不可逆损伤的面积。在组织病理学分析中，10和60CEM43的尺寸与病变的尺寸密切相关。在不可逆损伤区域和健康脑组织之间观察到明确的边界(≤1mm)。
结论：这项临床前评估表明，非冷却LITT系统能够精确地达到目标，并在安全范围内形成明确定义的病变，没有任何不良影响。MR测温软件提供了精确的接近实时的脑组织温度，通过软件可视化的病变尺寸与组织病理学结果密切相关。测试该系统在人类受试者中的有效性和安全性的进一步研究正在进行中。
