Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Interventional Radiology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Med Phys. 2023 Dec;50(12):7879-7890. doi: 10.1002/mp.16558. Epub 2023 Jul 6.
Thermochemical ablation (TCA) is a minimally invasive therapy under development for hepatocellular carcinoma. TCA simultaneously delivers an acid (acetic acid, AcOH) and base (sodium hydroxide, NaOH) directly into the tumor, where the acid/base chemical reaction produces an exotherm that induces local ablation. However, AcOH and NaOH are not radiopaque, making monitoring TCA delivery difficult.
We address the issue of image guidance for TCA by utilizing cesium hydroxide (CsOH) as a novel theranostic component of TCA that is detectable and quantifiable with dual-energy CT (DECT).
To quantify the minimum concentration of CsOH that can be positively identified by DECT, the limit of detection (LOD) was established in an elliptical phantom (Multi-Energy CT Quality Assurance Phantom, Kyoto Kagaku, Kyoto, Japan) with two DECT technologies: a dual-source system (SOMATOM Force, Siemens Healthineers, Forchheim, Germany) and a split-filter, single-source system (SOMATOM Edge, Siemens Healthineers). The dual-energy ratio (DER) and LOD of CsOH were determined for each system. Cesium concentration quantification accuracy was evaluated in a gelatin phantom before quantitative mapping was performed in ex vivo models.
On the dual-source system, the DER and LOD were 2.94 and 1.36-mM CsOH, respectively. For the split-filter system, the DER and LOD were 1.41- and 6.11-mM CsOH, respectively. The signal on cesium maps in phantoms tracked linearly with concentration (R = 0.99) on both systems with an RMSE of 2.56 and 6.72 on the dual-source and split-filter system, respectively. In ex vivo models, CsOH was detected following delivery of TCA at all concentrations.
DECT can be used to detect and quantify the concentration of cesium in phantom and ex vivo tissue models. When incorporated in TCA, CsOH performs as a theranostic agent for quantitative DECT image-guidance.
热化学消融（TCA）是一种正在开发的用于治疗肝细胞癌的微创疗法。TCA 直接将酸（乙酸，AcOH）和碱（氢氧化钠，NaOH）输送到肿瘤中，在那里酸/碱化学反应产生的热会导致局部消融。然而，AcOH 和 NaOH 都不是放射线可检测的，这使得监测 TCA 的输送变得困难。
我们通过利用氢氧化铯（CsOH）作为 TCA 的新型治疗诊断组件来解决 TCA 的图像引导问题，该组件可通过双能 CT（DECT）进行检测和定量。
为了量化可通过 DECT 明确识别的 CsOH 的最小浓度，在具有两种 DECT 技术的椭圆形体模（多能量 CT 质量保证体模，京都 Kagaku，京都，日本）中建立了检测限（LOD）：双源系统（SOMATOM Force，西门子医疗，Forchheim，德国）和分体滤光片，单源系统（SOMATOM Edge，西门子医疗）。确定了每个系统的双能量比（DER）和 CsOH 的 LOD。在进行定量映射之前，在明胶体模中评估了 CsOH 浓度定量准确性，并在离体模型中进行了评估。
在双源系统上，DER 和 LOD 分别为 2.94 和 1.36-mM CsOH。对于分体滤光片系统，DER 和 LOD 分别为 1.41 和 6.11-mM CsOH。两种系统上的体模中 CsOH 的信号均与浓度呈线性关系（R=0.99），双源和分体滤光片系统的 RMSE 分别为 2.56 和 6.72。在离体模型中，在 TCA 输送的所有浓度下均检测到 CsOH。
DECT 可用于检测和定量体模和离体组织模型中铯的浓度。当被纳入 TCA 时，CsOH 可作为用于定量 DECT 图像引导的治疗诊断剂。
