SPECT/CT 中 [Tc]Tc-MAA SPECT 和 CT 的配准减少用于精确肝脏放射性栓塞治疗计划。
SPECT and CT misregistration reduction in [Tc]Tc-MAA SPECT/CT for precision liver radioembolization treatment planning.
机构信息
Biomedical Imaging Laboratory (BIG), Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Taipa, Macau SAR, China.
Center for Cognitive and Brain Sciences, Institute of Collaborative Innovation, University of Macau, Taipa, Macau SAR, China.
出版信息
Eur J Nucl Med Mol Imaging. 2023 Jul;50(8):2319-2330. doi: 10.1007/s00259-023-06149-9. Epub 2023 Mar 6.
PURPOSE
Respiration and body movement induce misregistration between static [Tc]Tc-MAA SPECT and CT, causing lung shunting fraction (LSF) and tumor-to-normal liver ratio (TNR) errors for Y radioembolization planning. We aim to alleviate the misregistration between [Tc]Tc-MAA SPECT and CT using two registration schemes on simulation and clinical data.
METHODS
In the simulation study, 70 XCAT phantoms were modeled. The SIMIND Monte Carlo program and OS-EM algorithm were used for projection generation and reconstruction, respectively. Low-dose CT (LDCT) at end-inspiration was simulated for attenuation correction (AC), lungs and liver segmentation, while contrast-enhanced CT (CECT) was simulated for tumor and perfused liver segmentation. In the clinical study, 16 patient data including [Tc]Tc-MAA SPECT/LDCT and CECT with observed SPECT and CT mismatch were analyzed. Two liver-based registration schemes were studied: SPECT registered to LDCT/CECT and vice versa. Mean count density (MCD) of different volumes-of-interest (VOIs), normalized mutual information (NMI), LSF, TNR, and maximum injected activity (MIA) based on the partition model before and after registration were compared. Wilcoxon signed-rank test was performed.
RESULTS
In the simulation study, compared to before registration, registrations significantly reduced estimation errors of MCD of all VOIs, LSF (Scheme 1: - 100.28%, Scheme 2: - 101.59%), and TNR (Scheme 1: - 7.00%, Scheme 2: - 5.67%), as well as MIA (Scheme 1: - 3.22%, Scheme 2: - 2.40%). In the clinical study, Scheme 1 reduced 33.68% LSF and increased 14.75% TNR, while Scheme 2 reduced 38.88% LSF and increased 6.28% TNR compared to before registration. One patient may change from Y radioembolization untreatable to treatable and other patients may change the MIA up to 25% after registration. NMI between SPECT and CT was significantly increased after registrations in both studies.
CONCLUSION
Registration between static [Tc]Tc-MAA SPECT and corresponding CTs is feasible to reduce their spatial mismatch and improve dosimetric estimation. The improvement of LSF is larger than TNR. Our method can potentially improve patient selection and personalized treatment planning for liver radioembolization.
目的
呼吸和身体运动导致静态[Tc]Tc-MAA SPECT 与 CT 之间的配准错误，从而导致用于 Y 放射性栓塞治疗计划的肺分流分数（LSF）和肿瘤与正常肝比值（TNR）错误。我们旨在使用两种配准方案来减轻[Tc]Tc-MAA SPECT 与 CT 之间的配准错误，该方案基于模拟和临床数据。
方法
在模拟研究中，对 70 个 XCAT 体模进行了建模。使用 SIMIND 蒙特卡罗程序和 OS-EM 算法分别进行投影生成和重建。低剂量 CT（LDCT）在吸气末模拟用于衰减校正（AC）、肺和肝分割，而对比增强 CT（CECT）则模拟用于肿瘤和灌注肝分割。在临床研究中，对 16 例患者的数据（包括[Tc]Tc-MAA SPECT/LDCT 和 CECT 以及观察到的 SPECT 和 CT 不匹配）进行了分析。研究了两种基于肝的配准方案：SPECT 配准到 LDCT/CECT 以及反之亦然。比较了配准前后不同体积感兴趣区（VOI）的平均计数密度（MCD）、归一化互信息（NMI）、LSF、TNR 和基于分区模型的最大注入活性（MIA）。采用 Wilcoxon 符号秩检验。
结果
在模拟研究中，与配准前相比，配准显著降低了所有 VOI 的 MCD、LSF（方案 1：-100.28%，方案 2：-101.59%）和 TNR（方案 1：-7.00%，方案 2：-5.67%）以及 MIA（方案 1：-3.22%，方案 2：-2.40%）的估计误差。在临床研究中，方案 1 降低了 33.68%的 LSF，并增加了 14.75%的 TNR，而方案 2 降低了 38.88%的 LSF，并增加了 6.28%的 TNR。与配准前相比，一位患者可能从 Y 放射性栓塞治疗不可行变为可行，其他患者的 MIA 可能增加 25%。在两项研究中，配准后 SPECT 与 CT 之间的 NMI 显著增加。
结论
静态[Tc]Tc-MAA SPECT 与相应 CT 之间的配准是可行的，可以减少它们之间的空间不匹配，并提高剂量估计。LSF 的改善大于 TNR。我们的方法有可能改善肝脏放射性栓塞治疗的患者选择和个体化治疗计划。
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