体素内不相干运动成像鉴别乳腺良恶性病变的价值并与定量动态增强MRI对比

Differentiation of benign and malignant breast lesions: a comparative study of intravoxel incoherent motion and quantitative dynamic contrast enhanced-magnetic resonance imaging

背景与目的:乳腺癌是女性最常见的恶性肿瘤,体素内不相干运动(intravoxel incoherent motion,IVIM)是近年来发展的基于双指数计算模型的功能成像方法,可反映单纯扩散和灌注两种效应。该研究旨在探讨IVIM各参数的可重复性及鉴别诊断乳腺良恶性病变的价值,与定量动态增强MRI(dynamic contrast enhanced-magnetic resonance imaging,DCE-MRI)比较,并探讨两种成像方法灌注参数的相关性。方法:收集发现乳腺占位性病变并获得术后明确病理结果的患者56例,共61个病灶,其中良性病变30个,恶性病变31个。患者术前均行IVIM及DCE-MRI检查。2名放射科医师独立对图像进行后处理,获得IVIM参数(D、D~*、f值),DCE-MRI参数(K^(trans)、K_(ep)、V_e值)。采用组内相关系数(intraclass correlation coefficients,ICC)检测2名医师IVIM测量值的一致性;采用独立样本t检验比较乳腺良恶性病变各参数值的差异;对于差异有统计学意义的参数采用受试者工作特征(receiver operating characteristic,ROC)曲线评价其鉴别诊断乳腺良恶性病变的效能;采用Pearson相关分析比较IVIM灌注相关参数与DCE-MRI的相关性。结果:2名医师IVIM测量值的组内、组间重复性均较好(ICC≥0.730,P均<0.05)。乳腺恶性病变的D值低于良性病变,而f、K^(trans)及K_(ep)值高于良性病变,差异均有统计学意义(P<0.05),D~*、V_e值差异均无统计学意义(P>0.05)。D、f、K^(trans)、K_(ep)值鉴别诊断乳腺良恶性病变的ROC下面积分别为0.896、0.677、0.796、0.847。D与K^(trans)、K_(ep)的ROC下面积差异无统计学意义(P>0.05)。以1.07×10^(-3) mm^2/s为诊断阈值,D值特异度最高(86.67%),以0.54/min为诊断阈值,K_(ep)值的灵敏度最高(98.36%)。相关分析显示f与K^(trans)、K_(ep)值及D~*与K^(trans)值均呈弱正相关,相关系数r分别为0.373、0.360和0.294(P?均<0.05)。结论:IVIM参数在不同医师分析中重复性较好,IVIM与DCE-MRI均有助于鉴别诊断乳腺良恶性病变,两种成像方法在反映组织灌注情况中存在相关性。

Background and purpose： Breast cancer is one of the most common malignant tumors among women. Intravoxel incoherent motion （IVIM） is a functional imaging technique based on the theory of biexponential model developed in recent years, which can exhibit diffusion and perfusion effects. This study aimed to investigate thereproducibility of IVIM parameters and the value in the diagnosis of breast lesions, comparing with quantitative dynamic contrast-enhanced magnetic resonance imaging （DCE-MRI） parameters, to explore whether correlations exist among perfusion parameters. Methods： A prospective study was performed in 56 patients with pathologically confirmed benign lesions （n=30）, malignant tumors （n=31）. All patients underwent DCE-MRI and IVIM imaging. Two radiologists measured the images independently to obtain the parameters from IVIM （D, D＇,f） and DCE-MRI （Ktrans, Kep, V~）. The data consistency between two observers was calculated with intraclass correlation coefficient （ICC）. All parameters were statistically compared between benign lesions and malignant tumors using independent sample t test. The receiver operating characteristic （ROC） curve was used to evaluate the ability of the parameters in differentiation of benign and malignant breast lesions. Pearson correlation analyses were used among the IVIM and DCE-MRI parameters. Results： The agreement between 2 radiologists was good for all parameters （ICC〉~0.730, P〈0.05）. D value was significantly lower in malignant lesions than in benign lesions, while the f, Kns and Kep values were higher than those in benign lesions （P〈0.05）. The D＊ and Ve values showed no differences between benign and malignant breast lesions （P〉0.05）. The areas under the ROC curve for D,f, Ktrans and Kpwere 0.896, 0.677, 0.796 and 0.847, respectively. There was no significant difference in the area under ROC curve between D and/dras, neither between the D and Kep （P〉0.05）. The D value showed higher specificity （86.67%） with the threshold of 1.07 x 10.3 mmZ/s. The Kp value showed higher sensitivity （98.36%） with the threshold of 0.54/min. The fvalue exhibited a positive correlation with/rns and Kep value with r of 0.373 and 0.360 （P〈0.05）, respectively. D＊ was also poorly correlated positively withs with an r of 0.294. Conclusion： The IVIM parameters showed good reproducibility between different radiologists. Both IVIM and DCE-MRI could be helpful in differentiating between benign and malignant breast lesions with positive correlation of the perfusion fraction.