| part 1The Study on DCE-MRI in Rabbit VX2 Liver Tumor Model after RFAObjective:To explore the pathological characteristics and DCE-MRI findings of rabbit VX2 liver tumor model after RFA.Methods:Twenty rabbit liver VX2 tumor models were established by planting the tumor tissue suspension into rabbits' liver and then underwent MRI on the second week.Eighteen rabbit liver tumor models were successfully established,and then divided into contrast group(8)without any treatment undergoing MRI on the 3rd and 4th week sequentially,and experimental group(10)treated with RFA undergoing MRI within 24 hours,1 st(the same time with constrast group on the 3rd week)and 2nd week(the same time with constrast group on the 4th week)after treatment respectively.SEMENS VERIO 3.0 T system was performed with the sequences including FL2d-T1WI,TSE-T2WI and FL 2d-T1WI-vibe for DCE-MRI.The volume of tumors in contrast group and RFA ranges in the experimental group were measured and calculated respectively,and the characteristics of MR images were analyzed after each examnation.The various perfusion parameters of the tumor and the RFA ranges in border,center and peripheral liver tissues were measured by using available software on workstation(Tissue 4D,Syngo MR B17)including Ktrans,Kep and Ve.Two or three rabbits will be executed randomly after each examnation and then the others were executed to take out the livers on the last time of examnation.The multi places of specimen of tumors and RFA ranges would subject to Hematoxylin and eosin(HE)staining and CD34 immunohistochemical staining and then The cancer cells and the microvessel density(MVD)in different parts of tumors were observed under microscope.Results:The average volume of tumors in control group were(0.28±0.06)cm3?(1.38±0.48)cm3,(4.45±1.84)cm3 on the 2nd,3rd and 4th week respectively with statistically significant difference(p<0.05),while the volume of RFA ranges in the experimental group showed no statistically difference on 3 times MRI.For the control group's tumor on the 2nd,3rd and 4th week,the measured Ktrans in tumor border part were(0.823±0.202)min-1,(0.851±0.175)min-1,(0.902±0.146)min-1 higher than the central part(0.293±0.095)min-1,(0.269±0.109)min-1,(0.270±0.132)min-1 as well as peripheral normal liver tissue(0.491 ± 0.150)min-1,(0.466±0.130)min-1,(0.516±0.081)min-1 respectively at same time with statistically significant difference(p<0.05).For experimental group's RFA areas,the measured average values of Ktrans in edges of leisions were(1.030±0.217)min-1,(0.665 ± 0.089)min-1,(0.962 ±0.140)min-1,(0.887±0.120)min-1 at the day before RFA treatment and 24h,1w,2w after treatment respectively,and the Ktrans at 24h after treatment was significantly lower than other time with statistically significant difference(P<0.05).There was no statistically difference between any two groups for Kep and Ve.The histopathology examination showed that tumors in control group were squamous cell carcinoma and the cells were distributed densely in the edge but orther parts.For the experimental group's RFA areas,there was different reactions in different parts.The border of RFA areas showed hyperemic and hemorrhagic zone with many more inflammatory cells,and the centers showed grayish yellow coagulative necrosis at 24 hours after RFA.The border was fibered gradually at the 1st and 2nd week after RFA,and it would form dense envelope finally.The residual tumors were seen located in the outer edge of the ablation lesions in 8 cases of the 10 tumors after RFA treatment.MVD values in the edges of the tumors in control group were higher than the central part at each time.For the experimental group's RFA areas the average MVD value were 41.33±2.08,22.50±2.12,40.00±2.82,39.17±4.02 at the day before RFA treatment and 24h,1w,2w after treatment respectively,and the MVD value at 24h after treatment was significantly lower than other time with statistically significant difference(P<0.05).Conclusion:The MVD and Ktrans always maintain high level in the edges of rabbit VX2 liver tumor model,and that decreased within 24h after RFA treatment due to serious damage of tumor,but rised in later period because of residual tumors increasing.DCE-MRI perfusion imaging can be indirect response to pathological changes of RFA areas at different times by varying parameters.part 2The Evaluation of DCE-MRI in HCC after RFA Treatment Objective:To explore the value of DCE-MRI in evaluation HCC after RFA treatment.Materials and methods:The MRI data of 47 patients with HCC after treatment was analyzed in the First Affiliated Hospital of Guangxi Medical University from 2013 March to 2014 December.Male 39 cases,female 8 cases,age 37?75 years old,the average age was 54.2 ±9.7 years,median age 53 years.All of the 47 patients were diagnosed according to?primary liver cancer diagnosis and treatment standard?of 2011 before treatment and less than 3cm in diameter.All patients receieved MRI examination after the treatment of RFA,and were divided into four groups based on the MRI follow-up examination time,respectively within 48h after RFA,48h?1m,1?3m and over 3m.The RFA2000 RF treatment system was used in RFA operation with guidance of ultrasound.Magnetic resonance imaging device is the SIEMENS Verio 3.0 T system The relevant series that were examined included:FL2d-T1WI,TSE-T2WI fat suppression and FL2d-T1WI-vibe for dynamic contrast-enhanced MRI(DCE-MRI).Double blind analysis of the images were completed by two experienced radiologists after examination.MRI characteristics of liver cancer after RFA at different time were observed and analyzed,which included(1)the location,size,shape andchanges of peripheral liver parenchyma in all groups.(2)signal characteristics of T1WI and T2WI(3)Different enhancement types of the RFA lesions including ringlike enhancement,edge enhancement and nodular enhancement were observed on DCE-MRI to determine tumor ablation completely,residues or local tumor progression.Perfusion parameters determination including Ktrans,Kep and Ve values,the relationship between the above three quantiz parameters is Kep=Ktrans/Ve.In the pseudo color map generated by Tissue-4D software,pseudo color red part represents the high perfusion area,blue represents low perfusion zone,between is yellow.Selected region of interest(ROI)in the pseudo color mapre respectively,in order to measure the perfusion paremates of the edge?central of RFA,and peripheral liver parenchyma.The edge part of the ROI was selected as the reddest part of pseudo color map,and visible vessels should be avoided in selection of ROI in normal liver tissue.After ROI selected,the above parameters will be calculated automatically by Tissue-4D software.All data was processed with SPSS 17.0 statistical analysis software,and measurement data was showed by x±s.Chi-square test Fisher method was used for comparing the signal changes of RFA lesions in each time group and single factor analysis of variance for comparing perfusion parameters within group and between group.Results:There were 80 lesions analyzed in 47 patients(17,18,21 and 24 lesions in the group within 48h,48h?1m,1?3m and over 3m respectively).RFA areas(within 1m)showed hyperintense on T1WI,and the lesions within 48h and in 48h?1m showed annular or homogeneous hyperintense were respectively 14(82.35%14/17)and 13(72.77%12/18).The signal of RFA areas on T1WI decreased 1 month later and the proportions of annular or homogeneous hyperintense decreased.Five(23.81%5/21)and two(8.33%2/24)cases in 1?3m and over 3m appeared hyperintense respectively on T1WI,obviously lower than the former two groups with statistically significant difference(P<0.05).There were 10(58.82%10/17),11(61.11%11/18),and 15 cases(71.4%15/21)in the group of within 48h,48h?1m and 1?3m were mainly heterogeneous hypointense respectively on T2WI.The signal changed 3 months later so that there were 10 homogeneous hypointense(41.67%10/24)and 7 isodense(29.17%7/24)in the group of over 3m.The difference of signal changing between the group of over 3m and three other groups was statistically significant(P<0.05).The boundary of RFA areas in all time groups was well-defined on T1WI,but less well-defined on T2WI.There were 13(76.47%13/17)and 14(77.78%14/18)leisions showed obviously ringlike enhancement in the edge in the group of within 48h and 48h?1m respectively,and 20(83.33%20/24)cases showed mild ringlike or no enhancement in the group of over 3m.The above difference between the group of within 48h or 48h?1m and over 3m was statistically significant(P<0.05).The liver parenchyma around RFA areas showed more abnormal perfusion in the group of within 48h(64.71%11/17)and 48h?1m(72.22%13/18)than that in the group of 1?3m(23.81%5/21)and over 3m(4.17%1/24)respectively,with statistically significant difference(P<0.05).There were 14 cases(16 RFA lesions)among 47 patients with continuous MRI data at the time of within 48h,48h?1m and over 3m.The parameter Ktrans measured at the edge part of RFA lesions in the group of over 3m was(0.502±0.109)min-1 lower than that in the group of within 48h(0.805±0.117)min-1 and 48h?1m(0.771±0.073)min-1.Ktrans at the edge part of RFA leisions was higher than that at the central part at the same time(P<0.05).Conlusion:DCE-MRI showed that Ktrans at the edge of RFA areas gradually decreased,and the Ktrans at central coagulation necrosis always low in HCC after RFA treatment.MRI findings and the measured perfusion parameters on DCE-MRI of RFA leision can quantitatively reflect its pathological changes at different times. |
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