Cancer Center Amsterdam, Department of Medical Oncology, Academic Medical Center, Amsterdam, The Netherlands; Cancer Center Amsterdam, LEXOR (Laboratory for Experimental Oncology and Radiobiology), Academic Medical Center, Amsterdam, The Netherlands.
Department of Radiology & Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands; Department of Radiation Oncology, Academic Medical Center, Amsterdam, The Netherlands.
Int J Radiat Oncol Biol Phys. 2018 Nov 15;102(4):1052-1062. doi: 10.1016/j.ijrobp.2018.04.064. Epub 2018 May 4.
To compare 6 diffusion-weighted imaging (DWI) MRI models for response evaluation in patients with pancreatic ductal adenocarcinoma (PDAC).
DWI images were acquired at 3T for b = 0-600 s/mm in fourteen patients with advanced PDAC during 2 separate pretreatment sessions and 9 patients with (borderline) resectable PDAC pre and post neoadjuvant chemoradiation. Data was fitted with a mono-exponential (ADC), double mono-exponential to b = 0 and 100 s/mm (ADC), and b = 100 and 600 s/mm (ADC), IVIM model with D* free (D, f, D*) and fixed (D, f), tri-exponent (D, f, f), and stretched exponent model (DDC, α). Goodness of fit (adjusted R), tumor to normal tissue contrast, repeatability (coefficient of variation), and parameter correlations (Spearman's rho) were assessed for the repeated measures. Treatment induced changes were assessed and compared to the repeatability.
The mono-exponential model had the lowest goodness of fit in both tumor (R = 0.94) and normal-appearing pancreas (R = 0.88). Tumour to normal tissue contrast was higher for the 'non-diffusion' parameters (ADC, f, D*, f, f, α), with better repeatability for the diffusion parameters (ADC, ADC, D, DDC). Diffusion parameters were strongly correlated between the models (rho ≥0.81) and showed a general treatment associated increase. All models were able to identify individual treatment effects, showing a change greater than the repeatability in 5 out of 9 patients for at least one of the parameters.
Individual treatment evaluation is possible with all investigated DWI models, with treatment associated changes exceeding the repeatability. The double monoexponential fit with ADC and ADC is able to discriminate between non-diffusion and diffusion related effects, is measured fast and can be performed on most commercial scanners, making it an attractive alternative for the more advanced multiparametric models in radiotherapy treatment evaluation.
比较 6 种扩散加权成像（DWI）MRI 模型在胰腺导管腺癌（PDAC）患者中的疗效评估。
14 例晚期 PDAC 患者在 2 次预处理时，13T 扫描仪上采集 b 值为 0-600 s/mm 的 DWI 图像；9 例（边界）可切除 PDAC 患者在新辅助放化疗前后采集 DWI 图像。数据采用单指数（ADC）、双单指数（b 值为 0 和 100 s/mm 的 ADC、b 值为 100 和 600 s/mm 的 ADC）、IVIM 模型（D自由（D、f、D）和固定（D、f）、三指数（D、f、f）和拉伸指数模型（DDC、α）拟合。评估重复测量的拟合优度（调整 R）、肿瘤与正常组织对比、重复性（变异系数）和参数相关性（Spearman 相关系数）。评估并比较治疗引起的变化与重复性。
单指数模型在肿瘤（R=0.94）和正常胰腺（R=0.88）中的拟合优度最低。“非扩散”参数（ADC、f、D*、f、f、α）的肿瘤与正常组织对比更高，扩散参数（ADC、ADC、D、DDC）的重复性更好。各模型之间的扩散参数相关性较强（rho≥0.81），且一般与治疗相关的增加。所有模型均能识别个体治疗效果，在至少 1 例患者的至少 1 个参数中，观察到的变化大于重复性。
所有研究的 DWI 模型均可进行个体治疗评估，治疗相关变化超过重复性。双单指数拟合 ADC 和 ADC 能够区分非扩散和扩散相关效应，测量速度快，可在大多数商业扫描仪上进行，是放射治疗评估中更先进的多参数模型的一种有吸引力的替代方案。
