Abstract：
OBJECTIVE: Targeting accuracy presents a key factor in achieving maximal safe ablation in laser interstitial thermal therapy (LITT). The VarioGuide system has proven precise for brain biopsies, but data showing its accuracy in combination with LITT are limited. The aim of this study was to determine the phantom and in vivo accuracy of LITT probe placement using the VarioGuide system and to evaluate the effect of targeting error on maximum possible ablation volume.
METHODS: Stereotactic LITT probe placement was performed using the VarioGuide system in 3 phantom skulls. The same system was used in 10 patients treated with LITT, for which data were retrospectively analyzed. Target point error (TPE), target depth deviation (TDD), target lateral deviation (TLD), and angular deviation (AD) were derived from intraprocedural MRI scans of both the phantom and in vivo trajectories. In vivo, the effect of targeting error on the maximum reachable ablation was calculated as the difference between the planned maximal achievable tumor ablation (PTA) and the actual maximal achievable tumor ablation (ATA).
RESULTS: In total, 24 phantom and 16 in vivo trajectories were analyzed. In the phantom setting, the median TPE was 3.3 mm and median AD was 1.9°. Targeting accuracy significantly decreased for longer trajectories and those less perpendicular to the skull. In patients, the authors observed a comparable median TPE of 4.0 mm but significantly higher AD of 3.2°. In vivo, targeting inaccuracy resulted in a median decrease in maximum achievable ablation volume of 6% as compared to the planned trajectory.
CONCLUSIONS: The authors\' study indicates that utilizing the VarioGuide system in combination with LITT yields an average targeting error as large as 4 mm, which was smaller for shorter and straighter trajectories. In patients, targeting inaccuracy resulted in a median 6% decrease of the planned tumor ablation volume. These are important factors that should be considered in optimal case planning and patient selection in LITT.
METHODS: Stereotactic LITT probe placement was performed using the VarioGuide system in 3 phantom skulls. The same system was used in 10 patients treated with LITT, for which data were retrospectively analyzed. Target point error (TPE), target depth deviation (TDD), target lateral deviation (TLD), and angular deviation (AD) were derived from intraprocedural MRI scans of both the phantom and in vivo trajectories. In vivo, the effect of targeting error on the maximum reachable ablation was calculated as the difference between the planned maximal achievable tumor ablation (PTA) and the actual maximal achievable tumor ablation (ATA).
RESULTS: In total, 24 phantom and 16 in vivo trajectories were analyzed. In the phantom setting, the median TPE was 3.3 mm and median AD was 1.9°. Targeting accuracy significantly decreased for longer trajectories and those less perpendicular to the skull. In patients, the authors observed a comparable median TPE of 4.0 mm but significantly higher AD of 3.2°. In vivo, targeting inaccuracy resulted in a median decrease in maximum achievable ablation volume of 6% as compared to the planned trajectory.
CONCLUSIONS: The authors\' study indicates that utilizing the VarioGuide system in combination with LITT yields an average targeting error as large as 4 mm, which was smaller for shorter and straighter trajectories. In patients, targeting inaccuracy resulted in a median 6% decrease of the planned tumor ablation volume. These are important factors that should be considered in optimal case planning and patient selection in LITT.
摘要：
目的：靶向准确性是激光间质热疗（LITT）中实现最大安全消融的关键因素。VarioGuide系统已被证明是精确的脑活检，但是显示其与LITT结合的准确性的数据有限。本研究的目的是使用VarioGuide系统确定LITT探针放置的体模和体内准确性，并评估靶向误差对最大可能消融体积的影响。
方法：使用VarioGuide系统在3个体模头骨中进行立体定向LITT探针放置。相同的系统用于10例接受LITT治疗的患者，对其数据进行回顾性分析.目标点误差(TPE),目标深度偏差(TDD)，目标横向偏差(TLD),和角度偏差（AD）来自体模和体内轨迹的过程中MRI扫描。在体内,靶向误差对最大可达消融的影响计算为计划最大可达肿瘤消融(PTA)与实际最大可达肿瘤消融(ATA)之间的差值.
结果：总计，分析了24个体模和16个体内轨迹。在幻影设置中，TPE中位数为3.3mm,AD中位数为1.9°.对于较长的轨迹和较不垂直于头骨的轨迹，目标精度显着降低。在患者中，作者观察到相当的中位TPE为4.0mm,但AD显著高于3.2°.在体内,与计划轨迹相比,目标定位不准确导致最大可实现消融体积中位数减少6%.
结论：作者的研究表明，将VarioGuide系统与LITT结合使用会产生高达4mm的平均瞄准误差，对于较短和较直的轨迹，它较小。在患者中，靶向不准确导致计划的肿瘤消融体积中位减少6%.这些是在LITT的最佳病例计划和患者选择中应考虑的重要因素。
方法：使用VarioGuide系统在3个体模头骨中进行立体定向LITT探针放置。相同的系统用于10例接受LITT治疗的患者，对其数据进行回顾性分析.目标点误差(TPE),目标深度偏差(TDD)，目标横向偏差(TLD),和角度偏差（AD）来自体模和体内轨迹的过程中MRI扫描。在体内,靶向误差对最大可达消融的影响计算为计划最大可达肿瘤消融(PTA)与实际最大可达肿瘤消融(ATA)之间的差值.
结果：总计，分析了24个体模和16个体内轨迹。在幻影设置中，TPE中位数为3.3mm,AD中位数为1.9°.对于较长的轨迹和较不垂直于头骨的轨迹，目标精度显着降低。在患者中，作者观察到相当的中位TPE为4.0mm,但AD显著高于3.2°.在体内,与计划轨迹相比,目标定位不准确导致最大可实现消融体积中位数减少6%.
结论：作者的研究表明，将VarioGuide系统与LITT结合使用会产生高达4mm的平均瞄准误差，对于较短和较直的轨迹，它较小。在患者中，靶向不准确导致计划的肿瘤消融体积中位减少6%.这些是在LITT的最佳病例计划和患者选择中应考虑的重要因素。
