Background The aim of the study was to assess the role of diffusion-weighted imaging (DWI) to evaluate treatment response in patients with liver metastases of colorectal cancer. Patients and methods In this retrospective, observational cohort study, we included 19 patients with 18 responding metastases (R-Mets; follow-up at least one year) and 11 non-responding metastases (NR-Mets; local tumor recurrence within one year) who were treated with high-dose-rate brachytherapy (HDR-BT) and underwent pre- and post-interventional MRI. DWI (qualitatively, mean apparent diffusion coefficient [ADCmean], ADCmin, intraindividual change of ADCmean and ADCmin) were evaluated and compared between pre-interventional MRI, first follow-up after 3 months and second follow-up at the time of the local tumor recurrence (in NR-Mets, mean: 284 ± 122 d) or after 12 months (in R-Mets, mean: 387+/−64 d). Sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) for detection of local tumor recurrence were calculated on second follow up, evaluating (1) DWI images only, and (2) DWI with Gd-enhanced T1-weighted images on hepatobiliary phase (contrast-enhanced [CE] T1-weight [T1w] hepatobiliary phase [hb]) Results ADCmean significantly increased 3 months after HDR-BT in both groups (R-Mets: 1.48 ± 0.44 and NR-Mets: 1.49 ± 0.19 x 10−3 mm2;/s, p < 0.0001 and p = 0.01), however, intraindividual change of ADCmean (175% vs.127%, p = 0.03) and ADCmin values (0.44 ± 0.24 to 0.82 ± 0.58 x 10−3 mm2/s) significantly increased only in R-Mets (p < 0.0001 and p < 0.001). ADCmin was significant higher in R-Mets compared to NR-Mets on first follow-up (p = 0.04). Sensitivity (1 vs. 0.72), specificity (0.94 vs. 0.72), PPV (0.91 vs. 0.61) and NPV (1 vs. 0.81) could be improved by combining DWI with CE T1w hb compared to DWI only. Conclusions DW-MRI seems to be helpful in the qualitative and quantitative evaluation of treatment response after HDR-BT of colorectal metastases in the liver.

中文翻译：

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弥散加权成像在结直肠肝转移患者高剂量率近距离放射治疗后反应预测和评估中的作用

背景 本研究的目的是评估弥散加权成像 (DWI) 在评估结直肠癌肝转移患者治疗反应中的作用。患者和方法 在这项回顾性、观察性队列研究中，我们纳入了 19 名患者，其中 18 名有反应转移瘤（R-Mets；随访至少一年）和 11 名无反应转移瘤（NR-Mets；一年内局部肿瘤复发）接受高剂量率近距离放射治疗 (HDR-BT) 治疗并接受介入前和介入后 MRI 的患者。评估并比较介入前MRI、3个月后第一次随访和局部肿瘤发生时的第二次随访之间的DWI（定性、平均表观扩散系数[ADCmean]、ADCmin、ADCmean和ADCmin的个体内变化）复发（在 NR-Mets 中，平均值：284 ± 122 天）或 12 个月后（在 R-Mets 中，平均值：387+/-64 天）。在第二次随访时计算检测局部肿瘤复发的敏感性、特异性、阳性预测值 (PPV) 和阴性预测值 (NPV)，评估 (1) 仅 DWI 图像，以及 (2) 采用 Gd 增强 T1- 的 DWI肝胆期加权图像（对比增强 [CE] T1 权重 [T1w] 肝胆期 [hb]）结果 两组 HDR-BT 后 3 个月，ADCmean 显着增加（R-Mets：1.48 ± 0.44 和 NR-Mets： 1.49±0.19×10−3毫米2;/s, p < 0.0001 且 p = 0.01)，然而，ADC 的个体内变化均值 (175%与.127%，p = 0.03）和 ADC 最小值（0.44 ± 0.24 至 0.82 ± 0.58 x 10−3毫米2/s）仅在 R-Mets 中显着增加（p < 0.0001 和 p < 0.001）。首次随访时，R-Met 中的 ADCmin 显着高于 NR-Met（p = 0.04）。灵敏度（1与。0.72), 特异性 (0.94与。0.72），PPV（0.91与。0.61) 和净现值 (1与。与仅使用 DWI 相比，DWI 与 CE T1w hb 相结合可以改善 (0.81)。结论 DW-MRI 似乎有助于定性和定量评估结直肠肝转移瘤 HDR-BT 后的治疗反应。