不同对比剂剂量对乳腺癌模型DCE-MRI半定量参数影响的研究

Effect of different contrast agent doses on the semi-quantitative parameters of dynamic contrast-enhanced MRI of rodent mammary tumor model

目的探究不同对比剂剂量对Walker256大鼠模型进行磁共振动态增强扫描（DCE—MRI）后时间-信号曲线（TIC）类型及半定量参数的影响，以确定评估化疗疗效更为适当的参数。方法建立Walker256大鼠乳腺癌模型，随机分成3组，每组4只，Bruker 7T小动物MR扫描仪行MR平扫及DCE—MRI扫描，1-3组对比剂剂量分别为0．2、0．3、0．5mmol／kg。观察肿瘤MR表现和TIC类型及计算半定量参数，统计分析强化后各半定量参数是否在3个剂量组间存在差异。结果1-3组肿瘤TIC类型均为流出型。不同对比剂剂量在首过强化率（Efirst）、最大强化率（Emax）、最大排泄率（Ewash）和信号增强比（SER）之间的差异均具有统计学意义（P〈0．05）；而达峰值时间（Tpeak）和最大排泄速率（Vwash）无剂量依赖性，其差异均无统计学意义（P〉0．05）；各组平均信号值与峰值过后扫描次数之间具有高度负线性相关（r=-0．972，P=0．000；r=-0．971，P=0．000；r=-0．989，P=0．000）；回归方程斜率Slopewsah（流出斜率）在3组问差异均无统计学意义（P〉0．05）。结论TIC类型、Tpeak、Vwash及Slopewash不易受剂量影响，可使不同医疗中心的DCE数据具有一定的可比性，可作为监测新辅助化疗疗效的优选参数。

Objective To explore the effects of different doses of contrast agent （CA） on types of time-signal intensity curves （TICs） and semi-quantitative parameters after dynamic contrast-enhanced MRI （DCE-MRI） on Walker 256 murine breast tumor model. Methods A total of 12 rats burdened Walker256 breast cancer models were established and divided into 3 groups randomly, 4 in each group. Routine MR and DCE-MRI scans of the rats using Brnker Pharrnascan 7T MR scanner were performed. Doses for the 3 groups were 0.2, 0.3, and 0.5 mmol/kg, respectively. MR data, TICs types and semi-quantitative parameters from each different dose group were statistically studied and compared to observe the differences. Results Tumors were enhanced significantly after injection. The types of TICs in all tumors were the III pattern which was not influenced by CA doses. Semi-quantitative parameters of first enhancement （Efirst）, maximal enhancement （Emax）, washout enhancement （Ewash）, and signal enhancement ratio （SER） showed statistical differences among the three dose groups （P〈0.05）. Semi-quantitative parameters of time to peak （Tpeak） and washout velocity （Vwash） showed no statistical differences among the three dose groups （P〉0.05）. Mean signal intensity of each group was highly negatively linear correlated with scan times after the peak （r=-0.972, P=-0.000; r=-0.971, P=0.000;r=-0.989, P=0.000）. The washout slope （slopewash） showed no statistical differences among the three groups （P〉0.05）. Conclusions Injection doses of CA didn＇t change the TIC type, Tpeak, Vwash, and Slopewash. These parameters are comparable among different medical centers and can be considered as prior parameters to monitor the efficacy of neoadjuvant chemotherapy.