Partridge Savannah C, Steingrimsson Jon, Newitt David C, Gibbs Jessica E, Marques Helga S, Bolan Patrick J, Boss Michael A, Chenevert Thomas L, Rosen Mark A, Hylton Nola M
Department of Radiology, University of Washington, Seattle, WA 98195, USA.
Department of Biostatistics and Center for Statistical Sciences, Brown University, Providence, RI 02912, USA.
Tomography. 2022 Mar 4;8(2):701-717. doi: 10.3390/tomography8020058.
In diffusion-weighted MRI (DW-MRI), choice of b-value influences apparent diffusion coefficient (ADC) values by probing different aspects of the tissue microenvironment. As a secondary analysis of the multicenter ECOG-ACRIN A6698 trial, the purpose of this study was to investigate the impact of alternate b-value combinations on the performance and repeatability of tumor ADC as a predictive marker of breast cancer treatment response. The final analysis included 210 women who underwent standardized 4-b-value DW-MRI (b = 0/100/600/800 s/mm2) at multiple timepoints during neoadjuvant chemotherapy treatment and a subset (n = 71) who underwent test−retest scans. Centralized tumor ADC and perfusion fraction (fp) measures were performed using variable b-value combinations. Prediction of pathologic complete response (pCR) based on the mid-treatment/12-week percent change in each metric was estimated by area under the receiver operating characteristic curve (AUC). Repeatability was estimated by within-subject coefficient of variation (wCV). Results show that two-b-value ADC calculations provided non-inferior predictive value to four-b-value ADC calculations overall (AUCs = 0.60−0.61 versus AUC = 0.60) and for HR+/HER2− cancers where ADC was most predictive (AUCs = 0.75−0.78 versus AUC = 0.76), p < 0.05. Using two b-values (0/600 or 0/800 s/mm2) did not reduce ADC repeatability over the four-b-value calculation (wCVs = 4.9−5.2% versus 5.4%). The alternate metrics ADCfast (b ≤ 100 s/mm2), ADCslow (b ≥ 100 s/mm2), and fp did not improve predictive performance (AUCs = 0.54−0.60, p = 0.08−0.81), and ADCfast and fp demonstrated the lowest repeatability (wCVs = 6.71% and 12.4%, respectively). In conclusion, breast tumor ADC calculated using a simple two-b-value approach can provide comparable predictive value and repeatability to full four-b-value measurements as a marker of treatment response.
在扩散加权磁共振成像（DW-MRI）中，b值的选择通过探究组织微环境的不同方面来影响表观扩散系数（ADC）值。作为多中心ECOG-ACRIN A6698试验的二次分析，本研究的目的是调查不同b值组合对肿瘤ADC作为乳腺癌治疗反应预测标志物的性能和可重复性的影响。最终分析纳入了210名在新辅助化疗期间多个时间点接受标准化4-b值DW-MRI（b = 0/100/600/800 s/mm2）检查的女性，以及一个进行重测扫描的亚组（n = 71）。使用可变b值组合进行集中式肿瘤ADC和灌注分数（fp）测量。基于每个指标治疗中期/12周百分比变化对病理完全缓解（pCR）的预测通过受试者操作特征曲线（AUC）下的面积进行估计。可重复性通过受试者内变异系数（wCV）进行估计。结果显示，总体而言，双b值ADC计算与四b值ADC计算相比，预测价值不劣（AUC分别为0.60 - 0.61与0.60），对于ADC预测性最强的HR+/HER2-癌症也是如此（AUC分别为0.75 - 0.78与0.76），p < 0.05。使用两个b值（0/600或0/800 s/mm2）与四b值计算相比，并未降低ADC的可重复性（wCV分别为4.9 - 5.2%与5.4%）。替代指标快速ADC（b≤100 s/mm2）、慢速ADC（b≥100 s/mm2）和fp并未改善预测性能（AUC为0.54 - 0.60，p = 0.08 - 0.81），且快速ADC和fp的可重复性最低（wCV分别为6.71%和12.4%）。总之，作为治疗反应的标志物，使用简单双b值方法计算的乳腺肿瘤ADC可提供与完整四b值测量相当的预测价值和可重复性。
