体素内不相干运动参数在直肠癌术前分期中的诊断效能研究

Study on the diagnostic efficacy of intravoxel incoherent motion parameters within voxels in stage of rectal cancer before operation

目的:探讨体素内不相干运动(intravoxel incoherent motion,IVIM)参数在直肠癌术前分期中的诊断效能。方法:选取2018年6月—2019年3月于新疆医科大学附属肿瘤医院及石河子大学医学院第一附属医院接受直肠癌手术的97例直肠癌患者为研究对象,患者术前均进行磁共振成像(magnetic resonance imaging,MRI)及IVIM检查,并进行术后病理学分期,分析直肠癌术前IVIM参数在不同T分期、淋巴结转移及非转移的差异,以及IVIM参数(D^(*)和f值)与血管内皮生长因子(vascular endothelial growth factor,VEGF)和微血管密度(microvascular density,MVD)的相关性。结果:直肠癌术前IVIM参数(D、D^(*)、f值)在不同T分期(T_(1)+T_(2)与T_(3)+T_(4))之间差异有统计学意义(均P<0.05);单因素方差分析结果发现,D值在T分期(T_(1)+T_(2)与T_(3)+T_(4))中诊断效能最高;多因素logistic分析结果发现,D、D^(*)、f值3个参数综合诊断效能最高。在单纯T2和T3期两组之间,IVIM参数D、D^(*)值差异均有统计学意义(P均<0.05);单因素方差分析发现,D值在T2与T3期中诊断效能最高;多因素logistic分析发现,IVIM参数D、D^(*)这2个参数综合诊断效能最高。在直肠癌淋巴结转移及非转移方面,IVIM参数仅D值差异有统计学意义(P<0.05)。将IVIM参数在直肠癌淋巴结转移及非转移的差异性比较中差异有统计学意义的D值进行单因素方差分析发现,D值阈值为0.782×10^(-3) mm^(2)/s时,曲线下面积(area under curve,AUC)为0.635,阳性预测值(positive predictive value,PPV)为67.65%,阴性预测值(negative predictive value,NPV)为71.21%,灵敏度为83.37%,特异度为49.26%。对45例患者术后标本进行VEGF和MVD分析,并将VEGF和MVD与IVIM参数(D^(*)、f值)进行Spearman秩相关分析,结果发现,VEGF与D^(*)、f值之间的r为0.473、-0.432,相关系数假设检验差异有统计学意义(P均<0.05);而MVD与D^(*)、f值之间的r为-0.072、0.215,相关系数假设检验差异无统计学意义(P均>0.05)。结论:IVIM可辅助诊断直肠癌T分期情况及直肠癌淋巴结转移的状态,VEGF与D^(*)值具有正相关性,与f值有负相关性,在一定程度上可成为术前无创性预测VEGF的影像学指标。

Objective:To investigate the diagnostic efficacy of intravoxel incoherent motion(IVIM)parameters in preoperative staging of rectal cancer.Methods:From June 2018 to March 2019,97 patients with rectal cancer who underwent surgery in Cancer Hospital,Xinjiang Medical University and the First Affiliated Hospital of Shihezi University were selected as the study subjects.All patients underwent magnetic resonance imaging(MRI)and IVIM before surgery,and pathological staging after surgery.Postoperative pathological staging,the differences in preoperative IVIM parameters of rectal cancer at different T stages,lymph node metastasis and non-metastasis,and the correlation of IVIM parameters(D^(*) and f values)with vascular endothelial growth factor(VEGF)and microvascular density(MVD)were analyzed.Results:The preoperative IVIM parameters(D,D^(*) ,f values)of rectal cancer were statistically different between different T stages(T_(1)+T_(2) and T_(3)+T_(4))(both P<0.05);single factor analysis of variance found that D value was the highest in the T stage(T_(1)+T_(2) and T_(3)+T_(4));the multi-factor logistic analysis found that the D,D^(*) and f parameters hadthe highest comprehensive diagnostic efficiency.Between the two groups of simple T2 and T3 phases,the IVIM parameters D and D^(*) values were statistically different(both P<0.05);univariate analysis of variance found that the D value had the highest diagnosticefficacy in T2 and T3 phases;multivariate logistic analysis found that the IVIM parameters D and D^(*) had the highest comprehensivediagnostic efficiency.In lymph node metastasis and non-metastasis of rectal cancer,only the D value of IVIM parameters wasstatistically different(P<0.05).One-way analysis of variance was performed on the D value with statistically significant differencesin the comparison of lymph node metastasis and non-metastasis in rectal cancer.When the D value threshold was 0.782×10^(-3) mm^(2)/s,the area under curve(AUC)was 0.635 and the positive predictive value(PPV)was 67.65%.the negative predictive value(NPV)was 71.21%,sensitivity was 83.37%,and specificity was 49.26%.The VEGF and MVD analysis of postoperative specimensof 45 patients,and the spearman rank correlation analysis of VEGF,MVD and IVIM parameters(D^(*) and f values)found thatr between VEGF and D^(*) ,f values was 0.473,-0.432.The correlation coefficient hypothesis test was statistically significant(bothP<0.05).And r between MVD and D^(*) ,f values was-0.072,0.215,and the correlation coefficient hypothesis test was not statisticallysignificant(both P>0.05).Conclusion:IVIM can assist in the diagnosis of T stage and lymph node metastasis of rectal cancer.VEGF has a positive correlation with D^(*) value and a negative correlation with f value.To some extent,IVIM can be a noninvasiveimaging index to predict VEGF before operation.