Medical PET Group - Biological Imaging, Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Heidelberg, Germany.
Cancer Imaging. 2012 Sep 28;12(1):283-9. doi: 10.1102/1470-7330.2012.0033.
The use of dynamic positron emission tomography/computed tomography (dPET/CT) studies with [18F]deoxyglucose (FDG) in oncological patients is limited and primarily confined to research protocols. A more widespread application is, however, desirable, and may help to assess small therapeutic effects early after therapy as well as to differentiate borderline differences between tumour and non-tumour lesions, e.g., lipomas versus low-grade liposarcomas. The aim is to present quantification approaches that can be used for the evaluation of dPET/CT series in combination with parametric imaging and to demonstrate the feasibility with regard to tumour diagnostics and therapy management.
A 60-min data acquisition and short acquisition protocols (20-min dynamic series and a static image 60 min post injection) are discussed. A combination of a modified two-tissue compartment model and non-compartmental approaches from the chaos theory (fractal dimension of the time-activity curves) are presented. Fused PET/CT images as well as regression-based parametric images fused with CT or with PET/standardised uptake value images are demonstrated for the exact placement of volumes of interest.
The two-tissue compartmental method results in the calculation of 5 kinetic parameters, the fractional blood volume VB (known also as the distribution volume), and the transport rates k1 to k4. Furthermore, the influx according to Patlak can be calculated from the transport rates. The fractal dimension of the time-activity curves describes the heterogeneity of the tracer distribution. The use of the regression-based parametric images of FDG helps to visualise the transport/perfusion and the transport/phosphorylation-dependent FDG uptake, and adds a new dimension to the existing conventional PET or PET/CT images.
More sophisticated quantification methods and dedicated software as well as high computational power and faster acquisition protocols can facilitate the assessment of dPET/CT, and may find use in clinical routine, in particular for the assessment of early therapeutic effects or new treatment protocols in combination with the new generation of PET/CT scanners.
在肿瘤患者中，使用动态正电子发射断层扫描/计算机断层扫描（dPET/CT）与[18F]脱氧葡萄糖（FDG）的研究受到限制，主要限于研究方案。然而，更广泛的应用是可取的，它可以帮助评估治疗后早期的小治疗效果，并有助于区分肿瘤和非肿瘤病变之间的边界差异，例如脂肪瘤与低度脂肪肉瘤。目的是提出可用于评估 dPET/CT 系列的定量方法，结合参数成像，并证明其在肿瘤诊断和治疗管理方面的可行性。
讨论了 60 分钟的数据采集和短采集方案（20 分钟动态系列和注射后 60 分钟的静态图像）。提出了一种结合修正的两组织室模型和混沌理论的非房室方法（时间-活性曲线的分形维数）。演示了融合 PET/CT 图像以及与 CT 或 PET/标准摄取值图像融合的基于回归的参数图像，以便准确放置感兴趣的容积。
两组织室模型方法可计算 5 个动力学参数，即血液体积 VB 的分数（也称为分布体积）和转运速率 k1 到 k4。此外，根据 Patlak 可以从转运速率计算流入。时间-活性曲线的分形维数描述了示踪剂分布的异质性。FDG 的基于回归的参数图像的使用有助于可视化转运/灌注和转运/磷酸化依赖的 FDG 摄取，并为现有的常规 PET 或 PET/CT 图像添加了新的维度。
更复杂的定量方法和专用软件以及更高的计算能力和更快的采集方案可以促进 dPET/CT 的评估，并可能在临床常规中找到应用，特别是在评估早期治疗效果或与新一代 PET/CT 扫描仪结合的新治疗方案方面。
