Haseljić Hana, Frysch Robert, Kulvait Vojtěch, Werncke Thomas, Brüsch Inga, Speck Oliver, Schulz Jessica, Manhart Michael, Rose Georg
Institute for Medical Engineering, Otto von Guericke University Magdeburg, Magdeburg, Germany.
Research Campus STIMULATE, Otto von Guericke University Magdeburg, Magdeburg, Germany.
Med Phys. 2025 Apr;52(4):2074-2088. doi: 10.1002/mp.17652. Epub 2025 Jan 27.
The success of embolization, a minimally invasive treatment of liver cancer, could be evaluated in the operational room with cone-beam CT by acquiring a dynamic perfusion scan to inspect the contrast agent flow.
The reconstruction algorithm must address the issues of low temporal sampling and higher noise levels inherent in cone-beam CT systems, compared to conventional CT.
Therefore, a model-based perfusion reconstruction based on the time separation technique (TST) was applied. TST uses basis functions to model time attenuation curves. These functions are either analytical or based on prior knowledge (PK), extracted using singular value decomposition of the classical CT perfusion data of animal subjects. To explore how well the PK can model perfusion dynamics and what the potential limitations are, the dynamic cone-beam CT (CBCT) perfusion scan was simulated from a dynamic CT perfusion scan under different noise levels. The TST method was compared to static reconstruction.
It was demonstrated on this simulated dynamic CBCT perfusion scan that a set consisting of only four basis functions results in perfusion maps that preserve relevant information, denoise the data, and outperform static reconstruction under higher noise levels. TST with PK would not only outperform static reconstruction but also the TST with analytical basis functions. Furthermore, it has been shown that only eight CBCT rotations, unlike previously assumed ten, are sufficient to obtain the perfusion maps comparable to the reference CT perfusion maps. This contributes to saving dose and reconstruction time. The real dynamic CBCT perfusion scan, reconstructed under the same conditions as the simulated scan, shows potential for maintaining the accuracy of the perfusion maps. By visual inspection, the embolized region was matching to that in corresponding CT perfusion maps.
CBCT reconstruction of perfusion scan data using the TST method has shown promising potential, outperforming static reconstructions and potentially saving dose by reducing the necessary number of acquisition sweeps. Further analysis of a larger cohort of patient data is needed to draw final conclusions regarding the expected advantages of the TST.
肝癌的微创治疗方法——栓塞术的成功率，可在手术室通过锥形束CT进行动态灌注扫描以检查造影剂流动情况来评估。
与传统CT相比，重建算法必须解决锥形束CT系统固有的时间采样率低和噪声水平较高的问题。
因此，应用了基于时间分离技术（TST）的基于模型的灌注重建方法。TST使用基函数对时间衰减曲线进行建模。这些函数要么是解析型的，要么是基于先验知识（PK）的，先验知识是通过对动物受试者的经典CT灌注数据进行奇异值分解提取得到的。为了探究先验知识对灌注动力学的建模效果以及潜在局限性，在不同噪声水平下，从动态CT灌注扫描模拟动态锥形束CT（CBCT）灌注扫描。将TST方法与静态重建方法进行比较。
在此模拟动态CBCT灌注扫描中表明，仅由四个基函数组成的集合就能生成保留相关信息、对数据进行去噪且在较高噪声水平下优于静态重建的灌注图。基于先验知识的TST不仅优于静态重建，也优于基于解析基函数的TST。此外，研究表明，与之前假设的十次不同，仅八次CBCT旋转就足以获得与参考CT灌注图相当的灌注图。这有助于节省剂量和重建时间。在与模拟扫描相同的条件下重建的真实动态CBCT灌注扫描显示出保持灌注图准确性的潜力。通过目视检查，栓塞区域与相应CT灌注图中的区域相匹配。
使用TST方法对灌注扫描数据进行CBCT重建已显示出良好的潜力，优于静态重建，并且可能通过减少必要的采集扫描次数来节省剂量。需要对更大规模的患者数据队列进行进一步分析，以就TST的预期优势得出最终结论。
