Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94143, USA.
Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA 94143, USA.
Tomography. 2022 Mar 22;8(2):891-904. doi: 10.3390/tomography8020072.
Background parenchymal enhancement (BPE) of breast fibroglandular tissue (FGT) in dynamic contrast-enhanced breast magnetic resonance imaging (MRI) has shown an association with response to neoadjuvant chemotherapy (NAC) in patients with breast cancer. Fully automated segmentation of FGT for BPE calculation is a challenge when image artifacts are present. Low spatial frequency intensity nonuniformity due to coil sensitivity variations is known as bias or inhomogeneity and can affect FGT segmentation and subsequent BPE measurement. In this study, we utilized the N4ITK algorithm for bias correction over a restricted bilateral breast volume and compared the contralateral FGT segmentations based on uncorrected and bias-corrected images in three MRI examinations at pre-treatment, early treatment and inter-regimen timepoints during NAC. A retrospective analysis of 2 cohorts was performed: one with 735 patients enrolled in the multi-center I-SPY 2 TRIAL and the sub-cohort of 340 patients meeting a high-quality benchmark for segmentation. Bias correction substantially increased the FGT segmentation quality for 6.3-8.0% of examinations, while it substantially decreased the quality for no examination. Our results showed improvement in segmentation quality and a small but statistically significant increase in the resulting BPE measurement after bias correction at all timepoints in both cohorts. Continuing studies are examining the effects on pCR prediction.
背景实质增强（BPE）在动态对比增强磁共振成像（MRI）中的乳腺纤维腺体组织（FGT）与乳腺癌患者新辅助化疗（NAC）反应相关。当存在图像伪影时，全自动分割 FGT 进行 BPE 计算是一项挑战。由于线圈灵敏度变化导致的低空间频率强度不均匀性称为偏置或不均匀性，会影响 FGT 分割和随后的 BPE 测量。在这项研究中，我们在受限的双侧乳房体积上使用 N4ITK 算法进行偏置校正，并在 NAC 期间治疗前、早期治疗和方案间时间点的三个 MRI 检查中，比较基于未校正和校正图像的对侧 FGT 分割。对两个队列进行了回顾性分析：一个队列有 735 名患者参加了多中心 I-SPY 2 试验，340 名患者为分割的高质量基准。偏置校正后，6.3-8.0%的检查中 FGT 分割质量显著提高，而没有检查的质量显著下降。我们的结果表明，在两个队列的所有时间点，校正后分割质量都有所改善，并且校正后的 BPE 测量值略有但统计学上显著增加。正在进行的研究正在研究其对 pCR 预测的影响。
