兔VX2肝癌高能聚焦超声治疗后的磁共振灌注加权成像

MR perfusion-weighted imaging in rabbit models of hepatic VX2 tumors after high intensity focused ultrasound

目的探讨高能聚焦超声(HIFU)治疗兔VX2肝癌后的磁共振灌注加权成像(PWI)的成像技术及特征。方法新西兰大白兔20只,平均随机分成治疗组与对照组,制作肝癌模型。瘤株接种2周后进行常规MR及PWI扫描。此后治疗组行HIFU单次治疗,14d后对两组均行PWI检查,选取病灶与周围正常肝组织的感兴趣区(ROI),采用信号强度-时间曲线的最大信号下降斜率(SRSmax)作为定量指标,分析不同ROI的SRSmax下降程度及规律。结果对照组肿瘤中央区与瘤旁肝实质SRSmax的差异无统计学意义,治疗组内VX2瘤中央区、周边区及瘤旁肝实质SRSmax的差异均有统计学意义。治疗组与对照组肿瘤周边区SRSmax的差异有统计学意义。结论兔肝VX2瘤PWI表现与肿瘤坏死程度、范围基本相符,PWI可用于评价HIFU治疗后肝脏肿瘤的血管生成、破坏状况。

Objective To evaluate the imaging features of perfusion-weighted imaging （PWI） in the rabbit VX2 liver cancer after HIFU therapy. Methods Twenty New Zealand rabbits were randomly divided into treatment and control groups. Routine MR and PWI examinations were performed 2 weeks after tumor strain planted. After that, rabbits in the treatment group underwent HIFU treatment. PWI was performed after treatment in both groups 14 d after HIFU treatment in treatment group. ROls of lesions and near normal tissue were selected to test the blood flow value. Maximal signal reduction slope （SRSmax） was used as a quantitative parameter during PWI. Results Significant difference of SRSmax was found among center zone of tumor, peripheral zone and surrounding liver parenchyma in treatment group, also in the peripheral zone of tumor between treatment group and control group, but not between central and peripheral area of tumor in the treatment group. Conclusion PWI findings are basically consistant with tumor necrosis level and extent. PWI can be used to evaluate the formation and destroy of blood vessel after the HIFU treatment of liver tumor in rabbits.