Department of Neurosurgery and Neuro-Oncology, National Cancer Center Hospital, Chuo-ku, Japan.
Course of Advanced Clinical Research of Cancer, Juntendo University Graduate School of Medicine, Bunkyo-ku, Japan.
Jpn J Clin Oncol. 2020 May 5;50(5):512-518. doi: 10.1093/jjco/hyaa010.
Primary central nervous system lymphoma (PCNSL) responds relatively quickly to chemotherapy or radiotherapy. However, determination of a complete response after treatment is often difficult because of extremely light residual contrast enhancement on magnetic resonance images due to the effects of microhemorrhages and scar tissue formation. These small enhancing lesions define an unconfirmed complete response. The aim of this study was to investigate the usefulness of carbon-11-labeled methionine (11C-Met) positron-emission tomography (PET) for determining the treatment response of PCNSL.
Data for 36 patients who were treated for PCNSL between 2011 and 2015 and underwent magnetic resonance imaging and 11C-Met PET were reviewed. Magnetic resonance imaging findings were classified as complete response, unconfirmed complete response, and tumor mass (a composite of partial response, stable disease and progressive disease). PET images were evaluated, standardized uptake values were quantified, and the tumor-to-normal tissue count ratio (TNR) was calculated. Receiver operating characteristic curves were generated to determine the optimal cutoff TNRs.
The optimal TNRs for differentiating complete response and unconfirmed complete response from tumor mass were 1.83 (area under the curve, 0.951) and 1.80 (area under the curve, 0.932), respectively. The corresponding sensitivity and specificity values for the diagnosis of tumor mass were 82.4 and 100%, respectively, in the complete response group and 85.3 and 85%, respectively, in the unconfirmed complete response group.
A TNR of ≥1.80 can aid in the detection of active PCNSL using 11C-Met PET. Thus, 11C-Met-PET may be a useful tool for accurate evaluation of the treatment efficacy in PCNSL.
原发性中枢神经系统淋巴瘤（PCNSL）对化疗或放疗的反应相对较快。然而，由于微出血和疤痕组织形成的影响，磁共振成像上残留的对比增强非常轻微，治疗后确定完全缓解通常很困难。这些小的增强病变定义为未确认的完全缓解。本研究旨在探讨 11C-蛋氨酸（11C-Met）正电子发射断层扫描（PET）在确定 PCNSL 治疗反应中的作用。
回顾了 2011 年至 2015 年间接受 PCNSL 治疗并接受磁共振成像和 11C-Met PET 的 36 例患者的数据。磁共振成像结果分为完全缓解、未确认的完全缓解和肿瘤肿块（部分缓解、稳定疾病和进展性疾病的综合）。评估 PET 图像，量化标准化摄取值，并计算肿瘤与正常组织计数比（TNR）。生成受试者工作特征曲线以确定最佳截断 TNR。
区分完全缓解和未确认的完全缓解与肿瘤肿块的最佳 TNR 分别为 1.83（曲线下面积，0.951）和 1.80（曲线下面积，0.932）。在完全缓解组中，肿瘤肿块的诊断敏感性和特异性分别为 82.4%和 100%，在未确认的完全缓解组中分别为 85.3%和 85%。
TNR≥1.80 可有助于使用 11C-Met PET 检测活跃的 PCNSL。因此，11C-Met-PET 可能是准确评估 PCNSL 治疗效果的有用工具。
