中文摘要：

目的探讨兔肝VX2瘤MR灌注成像（PWI）的最佳对比剂剂量，并评价MR灌注成像对兔肝VX2瘤的研究价值。方法采用随机区组设计将20只新西兰VX2瘤兔分为5组，每组4只，分别给予5种不同浓度（0．05、0．10、0．20、0．30、0．50mmol／kg）的钆双胺注射液（Gd-DTPA-BMA），以相同的流率（2ml／s），进行T2^＊W梯度回波-平面回波成像（T2^＊W-GE-EPI），对得到的兔肝VX2瘤及正常肝实质血流灌注效果进行定量和定性分析。结果以剂量0．2mmol／kg时VX2瘤灌注具有峰值时刻（TOP，12．50s）早、达峰时间（TTP，7．50s）短、最大信号下降百分率（SRRmax，54．33％）满意和平均通过时间（MTT，35．00s）适中的优点，其TOP、TTP和MTT与正常肝实质比较差异有统计学意义（P〈0．05）。5种浓度随着对比剂剂量的增加，VX2瘤灌注的TOP、TTP逐渐缩短，SRRmax逐渐增大，MTT明显延长。结论0．2mmol／kg为最优化的兔肝VX2瘤PWI剂量。

英文摘要：

Objective To optimize the contrast medium concentration for MR perfusion weighted imaging（ PWI ） of hepatic VX2 carcinoma in rabbits, and to evaluate the diagnostic value of MR PWI. Methods Twenty New Zealand White rabbits with VX2 carcinoma were divided into 5 groups in a randomized block design, and T2^＊ -weighted imaging with gradient-echo EPI was performed in rabbits after intravenous administration of contrast agent （ Gadodiamide Injection, Gd-DTPA-BMA） with five different concentrations （0. 05,0. 10,0. 20,0. 30,0. 50 mmol/kg） at a injection rate of 2 ml/s. Quantitative and qualitative evaluations were performed in blood perfusion of VX2 carcinoma and normal hepatic parenchyma. Results The time of peak （TOP） and the time to peak （TIP） of perfusion in VX2 carcinoma were shortened, the maximum signal reduction ratio （SRRmax） increased gradually and the mean transit time （MTT） elongated obviously with the increase of contrast medium concentration.MR perfusion in VX2 carcinoma was characterized by early TOP （12.50 s）, short TTP （7. 50 s）, satisfactory SRRmax （54. 33% ） and adequate MTT （ 35.00 s） with the concentration of 0. 20 mmol/kg. The TOP, TTP and MTI of VX2 carcinoma were significantly different from those of normal hepatic parenchyma （ P ≤ 0. 05 ）. Conclusion The 0. 20 mmol/kg is the most optimized concentration for PWI of rabbits hepatic VX2 carcinoma.