The Correlation Between MDCT And Pathological Findings Of HCC After RFA Therapy: Experimental And Clinical Study

Objective:The purpose was to observe the findings of hepatic VX2 tumor in rabbitsafter radiofrequency ablation(RFA)using both unenhanced,contrast enhancedmulti-detector CT and CT perfusion.To analyse the CT attenuation values onpre-enhanced and tri-phase contrast-enhanced examination and different parametervaluesof CT perfusion among the different days after RFA therapy,to compare thedifferences between remnant tumor and inflammatory reaction after RFA therapy.Todiscuss the value of both contrast enhanced CT and perfusion CT in differentiatigremnant tumor from inflammatory reaction.The purpose was to observe the findingsof HCC after RFA using both unenhanced,triphase contrast enhanced MDCT andCT perfusion.To analyse the CT attenuation values on pre-enhanced,tri-phasecontrast-enhanced examination and different parameter values of CT perfusion amongthe different period after RFA therapy,to compare the differences between localtumor progression (LTP),intrahepatic distant recurrence (IDR)and inflammatoryreaction after RFA therapy.To discuss the value of both contrast enhanced CT andperfusion CT in differentiatig LTP,IDR from inflammatory reaction.Materials and Methods:Twenty-four rabbits with hepatic VX2 tumor were assignedinto four groups,6 rabbits each group.In each group,three rabbits were establishedthe remnant tumor model,the others three rabbits were no remnant tumor after RFAtherapy.Each group were evaluated by contrast enhanced CT and perfusion CTduring the course of ld,3d,7d,14d after RFA,respectively.After imaging evaluation,they will be killed and observed in pathology.To observe the findings of contrastenhanced CT and perfusion CT,and register the CT attenuation value and perfusionparameters value,acquire the time density curve and artifact color images of differentperfusion parameters such as BF,BV,MTT,PS and HAF.To compare the differencesof the CT attenuation value and perfusion parameters value between remnant tumorand inflammatory reaction after RFA therapy among the 4 groups,respectively.Todefine which phases of contrast enhanced CT and parameters of perfusion CT candifferentiate remnant tumor from inflammatory reaction effectively through statisticalanalysis. We studied 36 patients with 45 HCCs who were treated with percutaneous RFablation.Triphase contrast enhanced CT and perfusion CT were performed at the timeof lday,1 month,3 month,6month and 1 year after RFA therapy.There were 21,22,16,16,23 HCCs that were examined by both contrast enhanced CT and perfusionCT at 5 periods (that mentioned above)after RFA therapy,respectively.Among them,2,3,8,5,6 LTPs,IDRs were found at the 5 periods,respectively.There were 19,14,3 HCCs which had surrounding inflammatory reaction at the time of 1d,1m,3m,respectively.To compare the differences between LTP,IDR and inflammatoryreaction (hepatic tissure around RFA focuse at time of 6m and 1 y)on both the CTattenuation value of unenhanced,contrast enhanced CT and the perfusion parametersof perfusion CT.after RFA therapy.To discuss the value of the two methods of CTscan in differentiatig LTP,IDR and inflammatory reaction (hepatic tissure aroundRFA focuse).Results:There had no statistical differences between remnant tumor andinflammatory reaction on every phase of unenhanced and tri-phase contrast enhancedCT in the group of 1d and 3d after RFA therapy.They,however,had significantdifference on the arterial and portal venous phase in the group of 7d,and on thearterial phase in the group of 14d.There had significant difference between remnanttumor and inflammatory reaction on the perfusion parameter of BF in all the groups,and they had significant difference on the parameter of BV and HAF in all the groupsbut 7d group.Considered all the data of four groups,the perfusion parameter of BF,BV,HAF had significant difference in differentiating remnant tumor frominflammatory reaction through ROC analysis.There were four types of tissue can beseen on the pathological sample,from inner portion to outer portion were necrosisarea,inflammatory reaction and fibrous zone,remnant tumor and hepatic tissurewhich surrounding the RFA focus,there was no remnant tumor zone in the group ofablated completely.RFA necrosis area,inflammatory reaction area (transform tofibrous tissue after 7 days)and the area of hepatocellular edema can be seen onmicroscopy examination in the group of remnant tumor,and tumor cells can be seenbetween the area of inflammatory reaction and hepatocellular edema in the group ofablated completely. There had no statistical differences between LTP,IDR and inflammatoryreaction on every phase of unenhanced and tri-phase contrast enhanced CT at time ofld and lm.after RFA therapy.However,there had significant differences on theunenhanced CT scan and the phase of arterial and portal venous at time of 3m afterRFA therapy(P＜0.01).There had significant differences between LTP,IDR andhepatic tissue around RFA focuse on every phase of unenhanced and tri-phasecontrast enhanced CT at time of 6m and 1 y after RFA therapy.There had significantdifferences between LTP,IDR and inflammatory reaction on the perfusion parametersof BF,BV,HAF at time of ld,lm,3m after RFA therapy,however,they had nosignificant differences on the perfusion parameters of MTT and PS at all time afterRFA therapy,except for the PS at time of 3m(P＜0.05).There had significantdifferences between LTP,IDR and hepatic tissue around RFA focuse on the perfusionparameters of BF,PS and HAF at time of 6m and 1y,BV at 1y after RFA therapy.Considered all the data of earlier three groups,the perfusion parameter of BF,BV,HAF had significant difference in differentiating LTP,IDR from inflammatoryreaction through ROC analysis,the value of Az were 0.955,0.891,0.929,respectively.Conclusion:1.The remnant hepatic tumor of VX2 rabbits after RFA were alike thehumans'HCC residue and local recurrence,it can be copied easily and successfully.2.Ring like enhancement of RFA focuse on the contrast enhanced CTexamination may be based on the pathological change of inflammatory reactionaround it.Inflammatory reaction arrived its' peak at the day 3,then subsidedeventually,it can be substituted by fibrous tissue at day 14.3.It was hard to differentiate remnant tumor from inflammatory reaction atday 1 and day 3 using only triphase contrast enhanced CT examnination,however,itcan be done at day 7 and day 14.4.Inflammatory reaction may be appeared around the HCC focuse at earlierphase after RFA therapy,and subsided eventually at the subsequent 3 months.Theyhad similar enhancement in contrast enhanced CT scan between LTP,IDR andinflammatory reaction among part of cases.5.Tri-phase contrast enhanced CT scan could differentiate LTP,IDR from inflammatory reaction at time of 3m,and it could also differentiate between LTP,IDRand hepatic tissue around RFA focuse at time of 6m and 1 y after RFA therapy,that is,tri-phase contrast enhanced CT scan could meet the need of clinical diagnosis at timeof 3m,6m and ly after RFA therapy.Tri-phase contrast enhanced CT scan could notdifferentiate LTP,IDR from inflammatory reaction at time of ld and lm after RFAtherapy,because of their similar enhancement,it could differentiate throughmorphological change.6.Perfusion CT could differentiate LTP,IDR from hepatic tissue around RFAfocuse not noly on the parameters of BF,HAF at time of 6m and l y,but also BF,BV,HAF at time of ld,lm and 3m.Perfusion CT could make up the blind spot ofdifferentiate diagnosis that contrast enhanced CT could not do at the earlier phaseafter RFA therapy.7.We suggested that a new follow-up CT scan protocol after RFA therapyshould be performed at time of 1,3,6,9 and 12 month after RFA therapy.