兔VX2肝癌高能聚焦超声治疗后MR灌注加权成像的研究

目的 探讨兔VX2肝癌高能聚焦超声(HIFU)治疗后的MR PWI的成像技术及成像特征.方法 新西兰大白兔28只,采用组织块种植的方法制成28只兔VX2肝癌模型,使用1.5 T MR扫描仪行常规扫描后,将28只VX2肝癌模型兔采用随机数字表法分成治疗组与对照组,治疗组分为A、B、C 3个亚组,每组7只,分别于治疗后14、25和35 d对肿瘤行PWI检查;对照组7只不行HIFU治疗.选取病灶与周围正常肝组织的ROI,分别测最血流灌注值,PWI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,并行单因素方差分析比较其差异.结果 4组共23只VX2兔获得满意的信号强度-时间曲线,其中治疗组A、B、C 3个亚组分别为7、5和6只,3组肿瘤中央区SRSmax值分别为(12.6±3.4)、(9.8±2.6)、(1.0±0.4),差异有统计学意义(F=10.855,P<0.05);肿瘤周边区SRSmax值分别为(48.3±2.4)、(46.2±1.5)和(43.6±1.8),瘤旁肝实质SRSmax值分别为(14.4±3.0)、(12.2±1.4)和(14.8±5.0),差异均无统计学意义(P>0.05).3组不同ROI的SRSmax差异均有统计学意义(F值分别为7.435、8.625和12.595,P值均<0.05).结论 PWI可用于评价HIFU治疗后肝脏肿瘤的血管生成、破坏状况,有可能对不同方法治疗后的兔VX2肝癌的疗效评价进行定性分析.

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

Objective To discuss the imaging technology and characteristic of perfusion-weighted imaging in rabbit models of hepatic VX2 tumors. Methods Twenty-eight New Zealand rabbits were implanted in liver with VX2 tumor by tissue block. After routine scans were performed on 1.5 T MR scanner, 28 New Zealand white rabbits with VX2 carcinoma were divided randomly into treatment group and control group. Treatment group was divided randomly into group A, group B and group C, 7 animals per group. Perfusion weighted imaging(PWI) was performed in day 14, 25 and 35, respectively, after tumor implantation in all animals. Select the regions of interest (ROI) of the VX2 tumor center, tumor border and pars-tumor parenchyma. Maximal signal reduction slope ( SRSmax ) of the signal intensity versus time curves were created as quantitative variable, and the parameters were calculated and compared in all groups. Results Maximal signal reduction slope ( SRSmax ) of the signal intensity versus time curves were studied in 4 groups, 23 VX2 rabbits,7,5 and 6 in group A , B and C, respectively. The SRSmax of tumor center were ( 12. 6 ± 3.4), ( 9. 8 ± 2. 6 ) and ( 1.0 ± 0. 4 ), the difference was significant ( F = 10. 855, P < 0. 05 ). The SRSmax of tumor border were(48. 3 ± 2.4), (46. 2 ± 1.5 ) and (43. 6 ± 1.8 ) ( P > 0. 05 ). The SRSmax of para-tumor parenchyma were ( 14.4 ± 3.0 ), ( 12. 2 ± 1. 4 ) and ( 14. 8 ± 5.0 ) ( P > 0. 05 ). The difference was significant in different ROI in treatment groups( F value was 7. 435,8. 625 and 12. 595, respectively, P < 0. 05 ). Conclusion PWI can be used in evaluating the liver tumor angiogenesis and angio-degeneration with the treatment of HIFU. It will be possible for qualitative analysis of rabbit models of hepatic VX2 tumors by different treatments.