Dimitrakopoulou-Strauss Antonia, Strauss Ludwig
Medical PET-Group Biological Imaging Clinical Cooperation, Unit Nuclear Medicine, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
Hell J Nucl Med. 2006 Jan-Apr;9(1):10-21.
Positron emission tomography (PET) has found wide-spread use in oncology due to the relatively high accuracy in the staging, differential diagnosis and therapy monitoring. Most PET studies are performed as a whole body scan. In selected cases a semiquantitative analysis is performed, which is based on the calculation of standardized uptake values (SUV). The present studies were undertaken in order to evaluate the impact of dynamic PET studies in malignant diseases with respect to tumor diagnosis and therapy management. Dynamic data acquisition is superior to static images because is provides information about the tracer distribution with respect of time and space, in a region of interest. The impact of different compartmental and non-compartmental approaches for the diagnostics and therapy planning was also studied. The radiopharmaceuticals used for patient studies were: O-15-water, C-11-ethanol, F-18-fluorodeoxyglucose (FDG), F-18-fluorouracil (F-18-FU), and 6-F-18-fluoro-L-DOPA. A new evaluation strategy of dynamic PET studies based on an integrated evaluation including both compartment and non-compartment models as well as the use of SUV is presented. Furthermore, the parametric imaging including Fourier-analysis and regressions analysis was used.
PET-studies with labeled cytostatic agents provide informations about the transport and elimination of a cytostatic agent and help to predict the therapeutic outcome. The retention of the radiolabeled cytostatic agent F-18-FU in liver metastases of colorectal cancer was low after systemic application. Lesions with retention values >3.0 SUV and with <2.0 SUV correlated with negative and positive growth rates, respectively. A high F-18-FU retention (>2.96 SUV) was associated with longer survival times (>21 months). In contrast, patients with lower F-18-FU retention values (<1.2 SUV) survived no longer than one year. A higher diagnostic accuracy was obtained by using an integrated evaluation including both compartment and non-compartment models. (18)F-FDG studies for the diagnosis of soft tissue sarcomas showed a sensitivity and specificity of 91% and 88% for the primary tumors and 88% and 92% for the recurrences, respectively. Using a combination of SUV and transport rates, it was possible to further classify malignant soft tissue tumors with regard to tumor grading percentages of 84% of the G III, 37.5% of the G II, 80% of the G I tumors, as well as 50% of the lipomas and 14.3% of scar tissue were correctly classified using the integrated evaluation. In patients with bone tumors, integrated evaluation was also superior to SUV or visual evaluation leading to a sensitivity of 76% (for SUV: 54%), a specificity of 97% (for SUV: 91%) and an accuracy of 88% (for SUV: 75%). The diagnostic efficacy of SUV and of the fractal dimension of the time activity data of FDG was evaluated in 159 patients with 200 lesions of different tumors with respect to differential diagnosis and the prognosis of therapeutic outcome. Discriminant analysis revealed a diagnostic accuracy of 76.65% for all patients, 67.7% for the untreated group of patients and 83.44% for the pretreated patients. The advantage of parametric imaging is the visualization of one isolated parameter of the tracer s kinetic, like the phosphorylation in case of (18)F-FDG. Furthermore, the delineation of a tumor is better due to the absence of background activity. The presented data also demonstrate that parametric imaging based on Fourier transformation may be useful for the evaluation of the pharmacokinetics and effectiveness of regional therapeutic procedures. In conclusion, a semiquantitative analysis of PET data sets based on SUV is in general helpful and should be performed under standardized conditions, concerning the time after tracer application, the blood glucose level in case of (18)F-FDG, partial volume correction and the choice of reconstruction parameters. The combination of two SUV s, an early and a late one is a simple and usefull approach for the evaluation of a dynamic series in a clinical environment. PET studies with labeled cytostatic agents provide information about the transport and elimination of a cytostatic agent and help to predict the therapeutic outcome. Non-compartment models require further evaluation.
正电子发射断层扫描（PET）因其在肿瘤分期、鉴别诊断和治疗监测方面具有较高的准确性，已在肿瘤学领域得到广泛应用。大多数PET研究作为全身扫描进行。在特定情况下进行半定量分析，其基于标准化摄取值（SUV）的计算。本研究旨在评估动态PET研究在恶性疾病的肿瘤诊断和治疗管理方面的影响。动态数据采集优于静态图像，因为它能在感兴趣区域提供关于示踪剂在时间和空间上分布的信息。还研究了不同房室和非房室方法对诊断和治疗规划的影响。用于患者研究的放射性药物有：O-15-水、C-11-乙醇、F-18-氟脱氧葡萄糖（FDG）、F-18-氟尿嘧啶（F-18-FU）和6-F-18-氟-L-多巴。提出了一种基于综合评估的动态PET研究新策略，该评估包括房室和非房室模型以及SUV的使用。此外，还使用了包括傅里叶分析和回归分析在内的参数成像。
用标记的细胞抑制剂进行的PET研究可提供有关细胞抑制剂转运和消除的信息，并有助于预测治疗结果。全身应用后，放射性标记的细胞抑制剂F-18-FU在结直肠癌肝转移灶中的滞留率较低。滞留值>3.0 SUV和<2.0 SUV的病变分别与负生长率和正生长率相关。F-18-FU高滞留（>2.96 SUV）与较长生存期（>21个月）相关。相比之下，F-18-FU滞留值较低（<1.2 SUV）的患者生存期不超过一年。通过包括房室和非房室模型的综合评估可获得更高的诊断准确性。用于诊断软组织肉瘤的（¹⁸）F-FDG研究显示，原发性肿瘤的敏感性和特异性分别为91%和88%，复发性肿瘤的敏感性和特异性分别为88%和92%。结合SUV和转运率，可以进一步对恶性软组织肿瘤进行分级分类，G III级肿瘤的分级准确率为84%，G II级为37.5%，G I级为80%，脂肪瘤的分级准确率为50%，瘢痕组织的分级准确率为14.3%。在骨肿瘤患者中，综合评估也优于SUV或视觉评估，敏感性为76%（SUV为54%），特异性为97%（SUV为91%），准确性为88%（SUV为75%）。在159例患有200个不同肿瘤病变的患者中，评估了SUV和FDG时间活性数据分形维数在鉴别诊断和治疗结果预后方面的诊断效能。判别分析显示，所有患者的诊断准确率为76.65%，未治疗患者组为67.7%，预处理患者为83.44%。参数成像的优点是可以可视化示踪剂动力学的一个孤立参数，如（¹⁸）F-FDG情况下的磷酸化。此外，由于没有背景活性，肿瘤的轮廓更清晰。所呈现的数据还表明，基于傅里叶变换 的参数成像可能有助于评估区域治疗程序的药代动力学和有效性。总之，基于SUV对PET数据集进行半定量分析通常是有帮助的，并且应该在标准化条件下进行，包括示踪剂应用后的时间间隔、（¹⁸）F-FDG情况下的血糖水平、部分容积校正以及重建参数的选择。早期和晚期两个SUV值的组合是在临床环境中评估动态序列的一种简单且有用的方法。用标记的细胞抑制剂进行的PET研究可提供有关细胞抑制剂转运和消除的信息，并有助于预测治疗结果。非房室模型需要进一步评估。
