Institute of Biomedical Engineering, Bogazici University, Istanbul, Turkey.
Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey.
Curr Med Imaging. 2022;18(10):1061-1069. doi: 10.2174/1573405618666220303111026.
The prediction of pathological responses for locally advanced rectal cancer using magnetic resonance imaging (MRI) after neoadjuvant chemoradiotherapy (CRT) is a challenging task for radiologists, as residual tumor cells can be mistaken for fibrosis. Texture analysis of MR images has been proposed to understand the underlying pathology.
This study aimed to assess the responses of lesions to CRT in patients with locally advanced rectal cancer using the first-order textural features of MRI T2-weighted imaging (T2-WI) and apparent diffusion coefficient (ADC) maps.
Forty-four patients with locally advanced rectal cancer (median age: 57 years) who underwent MRI before and after CRT were enrolled in this retrospective study. The first-order textural parameters of tumors on T2-WI and ADC maps were extracted. The textural features of lesions in pathologic complete responders were compared to partial responders using Student's t- or Mann-Whitney U tests. A comparison of textural features before and after CRT for each group was performed using the Wilcoxon rank sum test. Receiver operating characteristic curves were calculated to detect the diagnostic performance of the ADC.
Of the 44 patients evaluated, 22 (50%) were placed in a partial response group and 50% were placed in a complete response group. The ADC changes of the complete responders were statistically more significant than those of the partial responders (P = 0.002). Pathologic total response was predicted with an ADC cut-off of 1310 x 10 mm/s, with a sensitivity of 72%, a specificity of 77%, and an accuracy of 78.1% after neoadjuvant CRT. The skewness of the T2-WI before and after neoadjuvant CRT showed a significant difference in the complete response group compared to the partial response group (P = 0.001 for complete responders vs. P = 0.482 for partial responders). Also, relative T2-WI signal intensity in the complete response group was statistically lower than that of the partial response group after neoadjuvant CRT (P = 0.006).
As a result of the conversion of tumor cells to fibrosis, the skewness of the T2-WI before and after neoadjuvant CRT was statistically different in the complete response group compared to the partial response group, and the complete response group showed statistically lower relative T2-WI signal intensity than the partial response group after neoadjuvant CRT. Additionally, the ADC cut-off value of 1310 × 10 mm/s could be used as a marker for a complete response along with absolute ADC value changes within this dataset.
磁共振成像（MRI）在新辅助放化疗（CRT）后预测局部晚期直肠癌的病理反应是放射科医生面临的一项挑战，因为残留的肿瘤细胞可能被误认为是纤维化。已经提出对 MR 图像的纹理分析来了解潜在的病理学。
本研究旨在使用 MRI T2 加权成像（T2-WI）和表观扩散系数（ADC）图的一阶纹理特征评估局部晚期直肠癌患者对 CRT 的反应。
本回顾性研究纳入了 44 例接受 MRI 检查的局部晚期直肠癌患者（中位年龄：57 岁），这些患者在 CRT 前后均接受了 MRI 检查。从 T2-WI 和 ADC 图上提取肿瘤的一阶纹理参数。使用学生 t 检验或曼-惠特尼 U 检验比较病理完全缓解者和部分缓解者的病变纹理特征。使用 Wilcoxon 秩和检验比较每组 CRT 前后的纹理特征。计算受试者工作特征曲线以检测 ADC 的诊断性能。
在评估的 44 例患者中，22 例（50%）被分为部分缓解组，50%被分为完全缓解组。完全缓解者的 ADC 变化明显大于部分缓解者（P=0.002）。在新辅助 CRT 后，ADC 截断值为 1310×10mm/s 时，预测病理完全反应的灵敏度为 72%，特异性为 77%，准确性为 78.1%。新辅助 CRT 后，完全缓解组的 T2-WI 偏度与部分缓解组相比有显著差异（完全缓解者 P=0.001，部分缓解者 P=0.482）。此外，新辅助 CRT 后，完全缓解组的相对 T2-WI 信号强度明显低于部分缓解组（P=0.006）。
由于肿瘤细胞向纤维化的转化，新辅助 CRT 后完全缓解组的 T2-WI 偏度与部分缓解组相比有统计学差异，新辅助 CRT 后完全缓解组的相对 T2-WI 信号强度明显低于部分缓解组。此外，在该数据集内，ADC 截断值 1310×10mm/s 可以与绝对 ADC 值变化一起用作完全缓解的标志物。
