Suo Shiteng, Lin Naier, Wang He, Zhang Liangbin, Wang Rui, Zhang Su, Hua Jia, Xu Jianrong
Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Philips Research China, Shanghai, China.
J Magn Reson Imaging. 2015 Aug;42(2):362-70. doi: 10.1002/jmri.24799. Epub 2014 Nov 19.
To compare three different curve-fitting methods for intravoxel incoherent motion (IVIM) analysis in breast cancer.
Diffusion-weighted imaging was acquired in 30 patients with breast cancer using seven b-values (0-800 s/mm(2) ). Three curve-fitting methods were used for biexponential IVIM analysis: a. Direct estimation of D (diffusion coefficient), D* (pseudodiffusion coefficient) and f (perfusion fraction) (Method 1), b. Estimation of D first and then D* and f (Method 2), c. Estimation of D and f first and then D* (Method 3). Goodness-of-fit, parameter precision (coefficient of variance [CV]), parameter difference and correlation with relative enhancement ratio (RER) and initial area under the curve (IAUC) from dynamic contrast-enhanced (DCE) MRI of the three methods were determined and compared.
Among the three biexponential methods, Method 1 best described most of the pixels (63.20% based on R(2) ; 44.52% based on Akaike Information Criteria). The CV of D calculated from Method 2/3 (14.95%/13.90%), the CV of D* from Method 2 (77.04%) and the CV of f from Method 3 (80.87%) were the lowest among the three methods. Significant difference was observed for each IVIM-derived parameter calculated from all the three methods (P = 0.000-0.005). Only the perfusion-related f value calculated from Method 2 was correlated with RER (r = 0.548; P = 0.002) or IAUC (r = 0.561; P = 0.001).
IVIM-derived parameters differ depending on the calculation methods. The two-step fitting method with D value estimation first was correlated with DCE MRI perfusion.
比较三种不同的曲线拟合方法用于乳腺癌体素内不相干运动（IVIM）分析。
对30例乳腺癌患者采用7个b值（0 - 800 s/mm²）进行扩散加权成像。采用三种曲线拟合方法进行双指数IVIM分析：a. 直接估计D（扩散系数）、D*（伪扩散系数）和f（灌注分数）（方法1）；b. 先估计D，再估计D和f（方法2）；c. 先估计D和f，再估计D（方法3）。确定并比较三种方法的拟合优度、参数精度（变异系数[CV]）、参数差异以及与动态对比增强（DCE）MRI的相对增强率（RER）和曲线下初始面积（IAUC）的相关性。
在三种双指数方法中，方法1对大多数像素的描述最佳（基于R²为63.20%；基于赤池信息准则为44.52%）。方法2/3计算的D的CV（14.95%/13.90%）、方法2计算的D*的CV（77.04%）和方法3计算的f的CV（80.87%）在三种方法中最低。从所有三种方法计算得到的每个IVIM衍生参数均观察到显著差异（P = 0.000 - 0.005）。仅方法2计算的灌注相关f值与RER（r = 0.548；P = 0.002）或IAUC（r = 0.561；P = 0.001）相关。
IVIM衍生参数因计算方法而异。先估计D值的两步拟合方法与DCE MRI灌注相关。
