Data from: Quantifying post- laser ablation prostate therapy changes on MRI via a domain-specific biomechanical model: preliminary findings

Focal laser ablation destroys cancerous cells via thermal destruction of tissue by a laser. Heat is absorbed, causing thermal necrosis of the target region. It combines the aggressive benefits of radiation treatment (destroying cancer cells) without the harmful side effects (due to its precise localization). MRI is typically used pre-treatment to determine the targeted area, and post-treatment to determine efficacy by detecting necrotic tissue, or tumor recurrence. However, no system exists to quantitatively evaluate the post-treatment effects on the morphology and structure via MRI. To quantify these changes, the pre- and post-treatment MR images must first be spatially aligned. The goal is to quantify (a) laser-induced shape-based changes, and (b) changes in MRI parameters post-treatment. The shape-based changes may be correlated with treatment efficacy, and the quantitative effects of laser treatment over time is currently poorly understood. This work attempts to model changes in gland morphology following laser treatment due to (1) patient alignment, (2) changes due to surrounding organs such as the bladder and rectum, and (3) changes due to the treatment itself. To isolate the treatment-induced shape-based changes, the changes from (1) and (2) are first modeled and removed using a finite element model (FEM). A FEM models the physical properties of tissue. The use of a physical biomechanical model is important since a stated goal of this work is to determine the physical shape-based changes to the prostate from the treatment, and therefore only physical real deformations are to be allowed. A second FEM is then used to isolate the physical, shape-based, treatment-induced changes. We applied and evaluated our model in capturing the laser induced changes to the prostate morphology on eight patients with 3.0 Tesla, T2-weighted MRI, acquired approximately six months following treatment. Our results suggest the laser treatment causes a decrease in prostate volume, which appears to manifest predominantly at the site of ablation. After spatially aligning the images, changes to MRI intensity values are clearly visible at the site of ablation. Our results suggest that our new methodology is able to capture and quantify the degree of laser-induced changes to the prostate. The quantitative measurements reflecting of the deformation changes can be used to track treatment response over time.聚焦激光消融（Focal laser ablation）通过激光对组织的热毁损作用破坏癌细胞。热量被组织吸收后，会导致靶区域发生热坏死。该技术兼具放射治疗摧毁癌细胞的积极效果，同时因其精准定位特性规避了有害副作用。磁共振成像（MRI）通常用于治疗前确定靶区域，并在治疗后通过检测坏死组织或肿瘤复发情况评估疗效。然而，目前尚无系统可通过磁共振成像定量评估治疗后对组织形态与结构产生的影响。 为量化此类变化，首先需对治疗前后的磁共振图像进行空间配准。本研究的目标为量化两项内容：（a）激光诱导的形状改变，以及（b）治疗后磁共振成像参数的变化。形状改变或可与治疗疗效相关联，而目前学界对激光治疗随时间推移产生的量化效应尚缺乏深入认知。 本研究尝试对激光治疗后腺体形态的变化进行建模，此类变化源自三方面因素：（1）患者体位配准差异，（2）膀胱、直肠等周围器官带来的变化，以及（3）治疗本身引发的变化。为分离出治疗诱导的形状改变，首先需对（1）和（2）带来的变化进行建模，并通过有限元模型（FEM）将其移除。有限元模型可对组织的物理特性进行建模。采用物理生物力学模型至关重要，因为本研究的既定目标是明确治疗引发的前列腺物理形状改变，因此仅允许符合物理规律的形变。 随后将使用第二个有限元模型，以分离出由治疗诱导的物理性形状改变。我们将所提模型应用于8名患者的前列腺激光诱导形态变化捕捉与评估，所用数据为治疗后约6个月采集的3.0特斯拉T2加权磁共振成像（T2-weighted MRI）。 研究结果显示，激光治疗会导致前列腺体积减小，该变化主要集中在消融部位。完成图像空间配准后，消融部位的磁共振成像强度值变化清晰可见。研究结果表明，我们提出的新方法能够捕捉并量化激光诱导的前列腺形态改变程度。反映形变变化的量化测量结果，可用于追踪随时间推移的治疗应答情况。