OBJECTIVES Conventional evaluation of anti-tumor activity on the basis of tumor size is inadequate for immune checkpoint inhibitors (ICIs). We therefore aimed to assess the usefulness of intravoxel incoherent motion magnetic resonance imaging (IVIM-MRI) for evaluation of the therapeutic efficacy of ICIs. MATERIALS AND METHODS A chest IVIM-MRI was performed before and 2, 4, and 8 weeks after administration of ICIs in patients with advanced non-small-cell lung cancer. Apparent diffusion coefficient (ADC), skewness of ADC (ADCskew), kurtosis of ADC (ADCkurt), true diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) were evaluated at each evaluation point and changes from the baseline (Δ). RESULTS Twenty patients were enrolled in this study. An increased ADC 8 weeks and decreased ADCkurt and ΔADCkurt 4 weeks after ICIs was associated with objective responses and longer progression-free survival (PFS). A decreased ΔADCskew at 4 weeks was associated with objective responses, disease control, and longer PFS and overall survival. There was no correlation between the efficacy of ICIs and D, D* and f. All of three patients who had pseudoprogression had decreased ΔADCskew at 4 weeks and two of them had decreased ΔADCkurt at 4 weeks. Inversely, all five patients who had progressive disease (PD) did not have increased ΔADCskew at 4 weeks and only one of them had decreased ΔADCkurt at 4 weeks. CONCLUSIONS Changes in histograms of ADC may be useful for predicting long-term efficacy and distinguishing between pseudoprogression and actual PD after ICIs.

中文翻译：

---

体内无相干运动磁共振成像技术可预测免疫检查点抑制剂在非小细胞肺癌患者中的长期疗效。

目的基于肿瘤大小的常规抗肿瘤活性评估不足以提供免疫检查点抑制剂（ICI）。因此，我们旨在评估体素不相干运动磁共振成像（IVIM-MRI）在评估ICI的疗效方面的实用性。材料与方法对晚期非小细胞肺癌患者，在ICI给药之前，给药后2、4、8周进行了胸部IVIM-MRI检查。在每个评估点评估表观扩散系数（ADC），ADC偏度（ADCskew），ADC峰度（ADCkurt），真实扩散系数（D），伪扩散系数（D *）和灌注分数（f），并从基线（Δ）。结果本研究招募了20名患者。ICI后4周ADC升高，ADCkurt和ΔADCkurt降低与客观反应和更长的无进展生存期（PFS）相关。4周时ΔADCskew降低与客观反应，疾病控制以及更长的PFS和总体生存率相关。ICI的功效与D，D *和f之间没有相关性。三名假进展的患者在第4周时均降低了ADC偏斜，其中有2位在第4周时均降低了ADCADCrt。相反，所有五位患有进行性疾病（PD）的患者在4周时均未出现ΔADCkurt升高，仅其中一名患者在4周时已降低了ΔADCkurt。结论ADC直方图的变化可能有助于预测长期疗效，并区分ICI后的假性进展与实际PD。