【作者】 蒋朝霞；

【导师】 彭卫军； 李文涛； 周良平； 顾雅佳；

【作者基本信息】 复旦大学 ， 影像医学与核医学， 2009， 博士

【摘要】 第一部分兔VX2肝癌模型功能磁共振成像的实验研究目的建立稳定的兔VX2肝癌模型,探讨磁共振扩散、灌注及波谱对该模型进行成像的技术可行性。方法选用16只新西兰大白兔,将VX2瘤组织碎块种植于肝包膜下,建立移植性肝癌模型。2周后将接种成功的VX2兔行常规MRI（包括T1WI、T2WI）、多个b值的扩散加权成像（DWI）、灌注成像（PWI）和磁共振波谱（MRS）,将所有原始图像传输至工作站进行后处理:①设定b值后重建扩散加权图像并生成ADC图;②绘制相对肝血容量图（rHBV）,选取ROI,获得信号强度—时间曲线;③用Function tool 2处理自动获取谱线后,根据基线及代谢峰情况进行质量评分。MRI扫描完毕后行DSA检查,并取肿瘤标本做病理学检查,包括常规H-E染色和免疫组化分析,使用的抗体有抗CD31、抗VEGF、抗p53抗体。结果①肝脏种植成功率93.8%（15/16）,共种植18个病灶,大部分为单发结节（12/15,80%）。②所有肿瘤在DWI上均成功检出,呈高信号,ADC图上呈低信号,b值升高时,DWI图像质量下降;肿瘤在rHBV伪彩图上呈红色,以周边区明显,灌注曲线满意;波谱采集技术成功率为100%,谱线质量为:1分2个,2分3个,3分9个,4分4个。③DSA显示肿瘤由肝左动脉供血,血供丰富。④肿瘤在肝内形成浸润性癌巢,CD31表达于兔肝VX2瘤血管内皮细胞,VEGF和p53分别在肿瘤细胞的胞浆和胞核中染色。结论兔VX2肝癌模型血供丰富,接种成功率高,DSA操作方便,行磁共振功能扩散、灌注和波谱成像成功率高,技术上可行。第二部分应用扩散加权成像早期评价肝癌TACE疗效的研究目的评价磁共振扩散成像在兔VX2肝癌动脉化疗栓塞（TACE）后疗效监测中的作用,并探讨兼顾ADC测量准确性及图像对比噪声比（contrast-tonoiseratio,CNR）的最佳b值。方法选用12只新西兰大白兔,将VX2瘤组织碎块种植于肝包膜下,建立移植性肝癌模型。2周后将接种成功的VX2兔行常规MRI（包括T1WI、T2WI）和多b值扩散加权成像（b=0,200,400,600,1000,2000 s/mm²）。MRI检查后用超液化碘油与阿霉素制成乳化栓塞剂行TACE治疗。治疗后3天行MRI复查,方法同前。扫描完成后将所有原始图像传输至工作站,设定b值后重建扩散加权图像并生成ADC图。由同一名放射科医生在DWI图像上肿瘤区、正常肝实质及背景分别放置感兴趣区（region of interest,ROI）,然后将每个ROI复制到相应的ADC图上。在一系列不同b值的DWI和ADC图上计算每个ROI的信号强度（signal intensity,SI）和ADC值,共测量三次,取平均值,并在所有DWI图像上测量每个肿瘤的CNR。检查完毕后将所有动物处死取肝脏做病理,测量肿瘤坏死范围,以百分数表示,并研究ADC值与肿瘤坏死百分数之间的相关性。使用单因素方差分析（One-way ANOVA）分别对治疗前、后不同b值条件下测得的ADC值、CNR作比较;使用配对t检验对治疗前、后的所有肿瘤ADC值和CNR进行比较;使用Pearson相关分析研究ADC值与肿瘤坏死百分数的关系。结果当b值升高时,DWI图像质量随之下降。同一病灶不同b值所测得的ADC值之间有显著性差异（P＜0.001）,当b=600,1000,2000 s/mm²时,治疗前后的ADC值具有显著性差异（P＜0.05）。同一病灶不同b值条件下的CNR之间有显著性差异（P=0.000）,当b=600,1000 s/mm²时,治疗前、后图像的CNR具有显著性差异（P＜0.05）。TACE治疗后,肿瘤平均坏死率为（89.1±10.6）%,除了b为200时,其它b值均显示ADC值与肿瘤坏死率正相关,尤其当b为1000或2000时,相关性更高（P＜0.01）。结论通过测量ADC值可以早期监测肝癌TACE的疗效;若要兼顾图像的CNR和肿瘤ADC值测量的准确性,则建议b值取1000 s/mm²。第三部分磁共振灌注成像评价兔VX2肝癌TACE疗效的研究目的通过研究兔VX2肝癌TACE治疗后的磁共振灌注（PWI）参数变化,并与微血管密度（MVD）和血管内皮生长因子（VEGF）相对照,探讨PWI在监测肝癌TACE疗效中的价值。方法选用24只新西兰大白兔,将VX2瘤组织碎块种植于肝包膜下,建立移植性肝癌模型。2周后将接种成功的VX2兔行常规MRI（包括T1WI、T2WI）和PWI检查。将24只兔平均分为A、B两组,A组动物MRI检查后用超液化碘油与阿霉素制成乳化栓塞剂行TACE治疗,B组不治疗。治疗后3天A、B两组均行MRI复查,扫描序列及参数同前。扫描完成后将所有原始图像传输至工作站,绘制相对肝血容量图（rHBV）,选取ROI,获得信号强度—时间曲线,测量以下指标:达峰时间（TTP）,最大信号下降率(SRR_max)和最大信号下降斜率（SS）。检查完毕后将所有动物处死取肝脏做免疫组化染色,计算MVD和VEGF染色强度。使用配对t检验比较治疗组和对照组肿瘤的各个灌注参数以及VEGF、MVD有无差别;用Pearson相关分析研究灌注参数与VEGF、MVD有无相关性。结果肿瘤周边高灌注区在rHBV伪彩图上呈红黄色,设ROI获得信号强度—时间曲线,肿瘤高灌注区的曲线呈陡直倒置的峰。A组肿瘤治疗后中央低灌注区范围较治疗前增大,部分肿瘤中央低灌注区的灌注曲线呈不规则的锯齿。治疗组的SRR_max、SS较对照组显著下降（P＜0.05）;TTP较对照组延长,但无显著性差异（P＞0.05）。治疗组肿瘤的MVD较对照组显著下降;VEGF较对照组表达增高,但无统计学差异。SRR_max、SS与对照组及治疗组的MVD均呈正相关,r分别为0.620、0.532,0.731、0.698（P＜0.05）,VEGF与各灌注参数之间均无相关性。结论SRR_max、SS与MVD密切相关,通过PWI检查可评价肿瘤TACE后的血流灌注变化。第四部分应用氢质子波谱早期评价兔VX2肝癌TACE疗效的研究目的探讨¹H-MRS作为定量分析方法早期评价肝癌TACE疗效的可行性。方法选用16只新西兰大白兔,将VX2瘤组织碎块种植于肝包膜下,建立移植性肝癌模型。2周后将接种成功的VX2兔行常规MRI（包括T1WI、T2WI）和¹H-MRS。MRI检查后用超液化碘油与阿霉素制成乳化栓塞剂行TACE治疗。治疗后3天行MRI复查,扫描序列及参数同前。扫描完成后将所有原始图像传输至工作站,根据基线及代谢峰情况进行质量评分,3分或4分的合格波谱通过SAGE软件进行定量分析,计算Cho与Lip峰高及峰下面积的比值。检查完毕后将所有动物处死取肝脏做病理,观察肿瘤坏死情况。对肿瘤治疗前、后的胆碱与脂质峰峰高和峰下面积比值使用配对t检验进行比较。结果治疗前采集到谱线15个,技术成功率为15/16（93.8%）,合格谱线13个;治疗后采集到谱线13个,技术成功率为13/16（81.3%）,合格谱线10个;治疗前后均获得可分析波谱的肿瘤有10例。治疗后Cho与Lip峰高及峰下面积的比值均较治疗前显著下降（P值分别为0.031和0.023,均＜0.05）。10例治疗前后均获得可分析谱线的肿瘤平均坏死率为（82.5±12.4）%。结论¹H-MRS通过相对定量检测Cho/Lip的变化,能早期评价VX2肝肿瘤对TACE治疗的反应,但¹H-MRS检查的技术成功率和稳定性还有待提高。更多还原

【Abstract】 PartⅠStudy of functional MR imaging in a rabbit model bearing VX2 liver tumorObjective To develope a rabbit model of liver tumor and investigate the feasibility of diffusion MR（DWI）,perfusion（PWI） and magnetic resonance spectroscopy（MRS） in this animal model.Methods Sixteen adult male New Zealand White rabbits were selected as carrier rabbits,the VX2 tumor cells were implanted into the left lobe of the liver,and thus developed the implanted model of hepatic carcinoma.Two weeks later,15 rabbits bearing VX2 tumors successfully underwent conventional MRI（including T2WI and T1WI）,DWI,PWI and MRS examination. All the raw data were transferred to the post processing workstation for further analysis.DSA and pathological examination were performed subsequently, immunohistochemical staining of CD31、VEGF and p53 were also performed. Results①Fifteen rabbits（93.8%） were implanted successfully,18 tumors were detected on MRI,most of them were solitary（12/15,80%）.②All tumors were detected on DWI,manifested as a hyper-intense lesion,whereas hypo-intense on ADC map.Quality of DWI degraded as the b value increasing.The tumor was red on rHBV map,the perfusion curves were satisfactory.MRS was successfully conducted in all tumors,the quality of MRS was:2 spectra scored 1;3 scored 2;9 scored 3;4 scored 4.③DSA showed the tumor was hypervascular,and the left hepatic artery exclusively supplies blood flow to the tumor.④CD31 expression was detected in the vascular endothelial cells,VEGF and p53 expression was revealed in the tumor cells. Conclusion The rabbit model bearing VX2 liver carcinoma is hypervascular and can be easily developed.It’s technically feasible to perform the diffusion-,perfusion-weighted MR and MRS study in the rabbit liver tumor. PartⅡMonitoring hepatic tumor response to TACE in rabbits by diffusion-weighted magnetic resonance imagingObjective To evaluate diffusion-weighted MR in assessing tumor response to transarterial chemoembolization（TACE） in a rabbit model,and to explore the diffusion gradient b-factor that optimizes both the measurement of apparent diffusion coefficient（ADC） and contrast-to-noise（CNR）.Methods VX2 carcinoma cells were implanted in the livers of 12 healthy New Zealand white rabbits.All 12 rabbits beating VX2 tumors were treated with TACE.Conventional and diffusion-weighted MRI with various b values（0,200,400,600,1000,2000s/mm²） was performed using the same protocol before and 3 d after being treated with TACE. ADC values and contrast-to-noise ratio（CNR） of each tumor pre- and post-treatment with different b factors were compared.Percentage of necrotic area in each rabbit at histological specimen was calculated.The ADCs and CNRs of the same tumor on different b values were analyzed by ANOVA;the ADCs and CNRs between pre- and post-treatment were compared by Paired-sample T Test;and the correlation between ADC values and extent of necrosis was analyzed by a Pearson’s correlation test. Results The quality of diffusion-weighted images diminished as the b value increased. ADCs and CNRs of the same lesion measured on different b-value DWI were significantly different（P＜0.05）;ADC values between pre- and post-treatment were significantly different when b=600,1000,2000s/mm²（P＜0.05）;CNRs between preand post-treatment were significantly different when b= 600,1000 s/mm²（P＜0.05）.The mean percentage of necrotic cells present within the tumor was（89.1±10.6）%.A significant positive correlation was found between ADC values and the extent of necrosis with all b values except for b200,a higher relative coefficient between ADC values and percentage of necrosis was found on DWI with b1000 and b2000（P＜0.01）.Conclusion DWI can early evaluate the tumor necrosis after TACE by measuring ADC values.Taking into account both CNR and ADC measurement,b value of 1000s/mm² is recommended. PartⅢMonitoring hepatic tumor response to TACE in rabbits by perfusion-weighted magnetic resonance imagingObjective To evaluate the value of perfusion-weighted MR on assessing tumor response to TACE in a rabbit model by measurement of PWI parameters,with comparison of MVD and VEGF expression in the tumor.Methods VX2 carcinoma cells were implanted in the livers of 24 healthy New Zealand white rabbits.Conventional and perfusion-weighted MRI was performed 2 weeks later.All 24 rabbits bearing VX2 tumors in the livers were divided randomly into two groups: group A underwent TACE treatment,while group B untreated.Three days after treatment,both groups performed MRI study using the same protocol as before,rHBV map was developed on the post processing workstation,ROI was placed on the tumor and the signal intensity-time curve was obtained.The following parameters were measured:time to peak（TTP）,the maximal signal reduction ratio(SRR_max) and steepest slope（SS）.The tumors were dissected and sliced,and MVD and the staining intensity of VEGF were evaluated.The perfusion parameters and VEGF,MVD between pre- and post-treatment were compared by Paired-sample T Test;and the correlation between perfusion parameters and VEGF,MVD was analyzed by a Pearson correlation test.Results The peripheral area of the tumor was hyperperfusioned, which was red on rHBV map.SRR_max、SS of the tumors in TACE group were significantly lower than those of control group（P＜0.05）;TTP was prolonged without significant difference（P＞0.05）.MVD of the tumors in TACE group were significantly lower than those of control group;while VEGF was higher without significant difference.There was a positive correlation between SRR_max、SS and MVD both in group A and B,and there was no correlation between VEGF and all perfusion parameters.Conclusion SRR_max、SS are closely correlated with MVD,PWI can evaluate the change of the tumor perfusion after TACE treatment. PartⅣEarly assessing hepatic tumor response to TACE in rabbits by ¹H magnetic resonance spectroscopyObjective To evaluate the feasibility of ¹H-MRS on quantitative assessment of tumor response to TACE.Methods VX2 carcinoma cells were implanted in the livers of 16 healthy New Zealand white rabbits.All 16 rabbits bearing VX2 tumors were treated with TACE.Conventional MRI and ¹H-MRS was performed using the same protocol before and 3 d after being treated with TACE.Raw data were transferred to the post processing workstation,and the quality of the MRS was scored.The spectra scored 3 or 4 were analyzed quantitatively by SAGE,and Cho/Lip ratios were calculated.Percentage of necrotic area in each rabbit at histological specimen was evaluated.The Cho/Lip ratios between pre- and post-treatment were compared by Paired-sample T Test.Results ¹H-MRS was performed successfully in 15 tumors pre-treatment whereas 13 tumors post-treatment. Ten of all the MR spectroscopic data could be analyzed further.The Cho/Lip ratios decreased significantly post-treatment by comparison with those of pre-treatment（P＜0.05）.The mean percentage of necrotic cells present within the tumor was（82.5±12.4）%.Conclusion ¹HMRS has the potential of evaluation of early metabolite change in hepatic tumor by measuring the change of Cho/Lip,but its reproducibility and stability need to be improved.更多还原