基于体素内不相干运动的多扩散梯度因子值MR扩散加权成像在淋巴瘤疗效评价中的初步研究

Multiple b value diffusion-weighted MRI based on intravoxel incoherent motion model applied to lymphoma-pilot study

目的：运用基于体素内不相干运动（IVIM）的多b值DWI，评价淋巴结性淋巴瘤的疗效。方法选择2012年11月至2013年11月经病理确诊的淋巴结性淋巴瘤患者22例。患者分别在化疗前、2个化疗周期后进行1.5 T MRI平扫及多b值的DWI扫描，然后计算真性扩散系数（D）、灌注分数（f）、假性扩散系数（D＊）值。2个化疗周期后对疗效进行评价，按疗效将淋巴结分为完全缓解（CR）、部分缓解（PR）、稳定（SD）、进展（PD）4组。化疗前CR、PR、SD组D、f值的比较用Kruskal-Wallis H检验，两两之间的比较采用Nemenyi法。化疗前CR、PR、SD组D＊值的比较采用单因素方差分析。PR组化疗前与化疗后D、f、D＊的比较用配对样本t检验。把PR组和CR组合并为一组，作为疗效较好组，把SD组作为疗效较差组。用ROC曲线评估IVIM所得参数对疗效的预测效能。结果22例淋巴瘤患者化疗前进行了MRI平扫及多b值的DWI扫描，21例患者2个化疗周期结束后进行了MRI复查。CR组49个病灶、PR组17个病灶、SD组8个病灶、PD组0个病灶。化疗前CR组、PR组、SD组D值分别为（0.63±0.26）×10-3、（0.57±0.10）×10-3、（0.42±0.04）×10-3mm2/s，3组间差异有统计学意义（H=12.944，P=0.002），CR组和PR组D值差异无统计学意义（χ2=0.072，P=0.965），SD组D值低于CR组和PR组（χ2值分别为12.090、10.684，P值分别为0.002、0.005）。化疗前CR、PR、SD组间f值和D＊值差异无统计学意义（H=2.312，P=0.315；F=0.535，P=0.588）。PR组化疗后D值为（1.03±0.37）mm2/s，较化疗前明显升高（t=－4.781，P=0.001）；f值化疗后为（9.39±4.52）%，较化疗前明显升高（t=－2.294，P=0.036）；D＊值为（99.72±42.12）×10-3mm2/s，较前（（90.37±45.33）×10-3mm2/s）轻度升高，但差异无统计学意义（t=－0.579， P=0.570）。根据ROC曲线分析表明，D值的阈值为0.48×10-3mm2/s时，预测效能最佳，敏感度和特异度分别为100.00%和75.76%。结论淋巴瘤化疗前D值可以对疗效进行预测，化疗后D值的改变可以监测疗效，对疗效进行早期评估。

Objective To evaluate treatment effect of nodal lymphoma by using multiple b value diffusion-weighted MRI based on intravoxel incoherent motion （IVIM） model. Methods From November 2012 to November 2013, 22 patients with pathology confirmed lymphoma in Guangdong General Hospital were chosen. Patients were examined on a 1.5 T MR scanner with plain MRI scan and multiple b value diffusion-weighted MRI scan before and after cycle two of chemotherapy. According to chemotherapy response which evaluated after cycle 2 of chemotherapy, lymphoma nodes were divided into four groups：complete response （CR）, partial response （PR）, stable disease （SD）, progressive disease （PD）. Kruskal-Wallis H test was used to compare prechemotherapy D value, f value among CR, PR, SD groups. Nemenyi test was used to compare prechemotherapy D value between the two of CR, PR, SD groups. One-way ANOVA was used to compare D＊value among CR, PR, SD groups. Paired-sample t test was used to compare D, f, D＊value＆nbsp;between before and after chemotherapy in PR group. CR and PR group were ascribed to curative group, and SD group ascribed to poor response group. ROC curve was used to evaluate the predictive efficiency of parameters derived from IVIM. Results Twenty-two lymphoma patients were scanned before chemotherapy and 21 patients were scanned after cycle 2 of chemotherapy. There were 49 lesions in CR group, 17 lesions in PR group, 8 lesions in SD group and no lesions in PD group. Prechemotherapy D value of CR, PR, SD group were （0.63±0.26）×10-3, （0.57±0.10）×10-3,（0.42±0.04）×10-3 mm2/s, respectively. There was significant difference among the three groups （H=12.944,P=0.002）. There was no statistically difference of prechemotherapy D value between CR and PR group （χ2=0.072,P=0.965）. Prechemotherapy D value was lower in SD group than that in CR group （χ2=12.090,P=0.002） and PR group （χ2=10.684,P=0.005）. There was no statistically difference of prechemotherapy f value among CR, PR, SD groups （χ2=2.312,P=0.315） or D＊value （F=0.535,P=0.588）. D value significantly increased after chemotherapy in PR group [（1.03±0.37）× 10-3 vs.（0.63 ± 0.26）× 10-3 mm2/s, t=-4.781, P=0.001]. f value significantly increased after chemotherapy in PR group [（9.39 ± 4.52）% vs.（6.44 ± 3.25）%, t=2.294, P=0.036]. D＊ value slightly increased after chemotherapy but with no statistical difference in PR group [（99.72 ± 42.12）× 10-3 vs.（90.37 ± 45.33）× 10-3 mm2/s, t=-0.579, P=0.570]. When a D value of 0.48 × 10-3 mm2/s was used as the threshold value for predicting chemotherapy response, the best results were obtained with sensitivity of 100.00%and specificity of 75.76%.Conclusions Prechemotherapy D value can predict chemotherapy response and D value can monitor chemotherapy response in lymphoma.