Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida, United States of America.
Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee, United States of America.
PLoS One. 2018 Jul 6;13(7):e0199190. doi: 10.1371/journal.pone.0199190. eCollection 2018.
The recent emergence of laser interstitial thermal therapy (LITT) as a frontline surgical tool in the management of brain tumors and epilepsy is a result of advances in MRI thermal imaging. A limitation to further improving LITT is the diversity of brain tissue thermoablative properties, which hinders our ability to predict LITT treatment-related effects. Utilizing the mesiotemporal lobe as a consistent anatomic model system, the goal of this study was to use intraoperative thermal damage estimate (TDE) maps to study short- and long-term effects of LITT and to identify preoperative variables that could be helpful in predicting tissue responses to thermal energy.
For 30 patients with mesiotemporal epilepsy treated with LITT at a single institution, intraoperative TDE maps and pre-, intra- and post-operative MRIs were co-registered in a common reference space using a deformable atlas. The spatial overlap of TDE maps with manually-traced immediate (post-ablation) and delayed (6-month) ablation zones was measured using the dice similarity coefficient (DSC). Then, motivated by simple heat-transfer models, ablation dynamics were quantified at amygdala and hippocampal head from TDE pixel time series fit by first order linear dynamics, permitting analysis of the thermal time constant (τ). The relationships of these measures to 16 independent variables derived from patient demographics, mesiotemporal anatomy, preoperative imaging characteristics and the surgical procedure were examined.
TDE maps closely overlapped immediate ablation borders but were significantly larger than the ablation cavities seen on delayed imaging, particularly at the amygdala and hippocampal head. The TDEs more accurately predicted delayed LITT effects in patients with smaller perihippocampal CSF spaces. Analyses of ablation dynamics from intraoperative TDE videos showed variable patterns of lesion progression after laser activation. Ablations tended to be slower for targets with increased preoperative T2 MRI signal and in close proximity to large, surrounding CSF spaces. In addition, greater laser energy was required to ablate mesial versus lateral mesiotemporal structures, an effect associated with laser trajectory and target contrast-enhanced T1 MRI signal.
Patient-specific variations in mesiotemporal anatomy and pathology may influence the thermal coagulation of these tissues. We speculate that by incorporating demographic and imaging data into predictive models we may eventually enhance the accuracy and precision with which LITT is delivered, improving outcomes and accelerating adoption of this novel tool.
激光间质热疗（LITT）作为脑肿瘤和癫痫治疗的一线手术工具的出现，是 MRI 热成像技术进步的结果。进一步提高 LITT 疗效的一个限制因素是脑组织热消融特性的多样性，这阻碍了我们预测 LITT 治疗相关效果的能力。本研究利用内侧颞叶作为一个一致的解剖模型系统，旨在利用术中热损伤估计（TDE）图谱研究 LITT 的短期和长期效果，并确定术前变量，这些变量可能有助于预测组织对热能的反应。
对在一家机构接受 LITT 治疗的 30 例内侧颞叶癫痫患者，在共同参考空间中，使用可变形图谱对术中 TDE 图谱和术前、术中及术后 MRI 进行配准。使用 Dice 相似系数（DSC）测量 TDE 图谱与手动追踪的即刻（消融后）和延迟（6 个月）消融区之间的空间重叠。然后，受简单热传递模型的启发，从 TDE 像素时间序列中提取一阶线性动力学拟合的消融动力学，对杏仁核和海马头部进行量化，允许分析热时间常数（τ）。分析这些指标与 16 个独立变量的关系，这些变量来自患者人口统计学、内侧颞叶解剖、术前影像学特征和手术过程。
TDE 图谱与即刻消融边界紧密重叠，但与延迟成像上看到的消融腔相比明显更大，特别是在杏仁核和海马头部。在颞周脑脊液空间较小的患者中，TDE 更准确地预测了延迟 LITT 效果。术中 TDE 视频分析显示，激光激活后病变进展的模式不同。对于术前 T2 MRI 信号增加和靠近大的周围 CSF 空间的目标，消融速度较慢。此外，内侧颞叶结构的消融需要更大的激光能量，这与激光轨迹和目标对比增强 T1 MRI 信号有关。
内侧颞叶解剖和病理学的个体差异可能影响这些组织的热凝固。我们推测，通过将人口统计学和影像学数据纳入预测模型，我们最终可能会提高 LITT 治疗的准确性和精度，改善治疗效果，并加速这种新工具的应用。
