The Establishment Of The Rabbit Vx2 Nasopharyngeal Tumor Model And Its Growth Characteristics Of 18f-fdg Pet-ct, Mri,, Pathology Series Study

Objective To establish a rabbit VX2 nasopharyngeal carcinoma(NPC)model and observe its growth and neck lymph node metastasis and distance metastasis pattern.Meanwhile,to investigate character from the 18F-FDG PET-CT,MRI image combined with the results of the pathology.Methods After anesthesia,tumor tissues from the VX2 NPC New Zealand rabbit was made the fluid with concentrating 1-2×10~7/ml,intracutaneous injecting VX2 tumor cell on the rabbits' groin to passage.Then tumor tissue mass suspension was injected into rabbit's nasopharynx guided by CT image.Detected by CT,VX2 NPC models were built in 41 rabbits after transplanted for 2-4 weeks.Therefore,the growth and metastatic character were observed by 18F-FDG PET-CT and MRIin addition to the specimen obtained by naked eyes and the results from pathology.Results Nasopharyngeal tumor in 37 rabbits were successfully formed,in the rate of 90.2%(37/41)after transplanted for 2-4 weeks.7 of the a total30 rabbits in the study died by accident.We can see the nasopharyngeal cancer cell have grown fast and expanded to a variety of critical anatomical structures,such as parapharyngeal spaces,nasal cavities,oropharynx,skull base,clivus,infratemporal fossa,cavernous and so on.Pathology of NPC was confirmed to be a low differentiation for squamous cell carcinoma.The metastasic rate of neck lymph nodes was 93.3%(28/30)and the metastasic ratio in double sides of neck lymph nodes was 43.3%(13/30).Lung metastases were found in two rabbits-in rate of 6.7%.Nasopathrynx structure and surrounding organs were clearly observed by 18F-FDG PET-CT,MRI.Conclusions We had successfully built a rabbit VX2 nasopharyngeal carcinoma model with high successful rate.Its disease progress of rabbit VX2 NPC model were resembling to the human NPC.18F-FDG PET-CT,MRI can clearly display the structure of nasopathrynx and surrounding organs.So it is an ideal animal model to study human NPC disease. Objective To establish VX2 NPC model and study the value of 18F-deoxyglucose positron emission tomography computed tomography (18F-FDG PET-CT)and Magnetic resonance imaging(MRI)on neck lymph node(LN)metastasis in rabbit VX2 nasopharyngeal carcinoma.Methods One week after the establishmentof 30 VX2 NPC models, 18F-FDG PET-CT,MRI,the anatomy and pathology diagnoses were completed in 48 hours.To observe neck lymph node from image compared with the result from the anatomy finding and the pathology.Results 1.53 neck lymph nodes were pick up from 30 VX2 NPC rabbits by resecteding,there were 42 positive lymph nodes confirmed by pathology.28 rabbits occurred neck lymph node metastasis,in the metastatic rate of 93.3%(28/30),and metastatic rate in double sides neck lymph node was 43.3%(13/30).2.Positive lymph nodes had significantly correlated with the lymph node volume with short diameter(P=0.003,0.008).Volume and short diameter of positive lymph node was larger than that of negative lymph node. 25 of 42 positive lymph nodes as volume≥0.5cm3 and 23 ones could be found by 18F-FDG PET-CT,in rate of 92%.9 of 17 positive lymph nodes smaller than 0.5cm3 could be found with 18F- FDG PET-CT,in rate of 52.9%.18F-FDG PET-CT could get correctly diagnosis with all of 6 positive lymph nodes(100%,6/6).The short diameter were 1.1-1.7cm,21 nodes from 24 positive lymph nodes(87.5%)were found as short diameter in 0.5-1cm.Even If short diameter were＜0.5cm,18F-FDG PET-CT also can be found 5 of 12 positive lymph nodes(41.7%),7 false negetive.3.The sensitivity,specificity, diagnostic accuracy,positive and negative predictive values in 18F-FDG PET-CT were 76.2%,100%,81.1%,100%respectively and 52.4% and 59.5%,90.9%,66.0%,96.2%and 37%in MRI respectively.4. The truth positive and false negative of 18F-FDG PET-CT diagnosis were significantly correlated with volume of lymph node.The volume of truth position were larger than that of false negative,there were significantly different between them(P=0.001).4.Among the 12 lymph nodes of 18F-FDG PET-CT(+)MRI(-)were positive nodes confirmed by pathology diagnoses.5.The lymph nodes of 18F-FDG PET-CT(-)MRI(+)were only 1 negative and 5 positives.6.The volume based on 18F-FDG PET-CT,MRI images were larger than that of actually measure in specimens,but the volume on 18F-FDG PET-CT images were not significantly different from actually measure volume(P=0.107),MRI was significantly different from actually measure volume(P=0.001).Conclusion 1.the Characteristics of higher rate of neck lymph node metastatic in VX2 NPC were similar to the human NPC;2. 18F-FDG PET-CT was reliable and accurate in detecting the neck lymph node≥0.5cm3 or short diameter＞5cm.18F-FDG PET-CT is still an important tool to detect the neck lymph node of volume＜0.5cm3 or short diameter≤5cm.3.The volume of truth position were significantly larger than that of false negetive.4.combide the 18F-FDG PET-CT with MRI we can find more positive neck lymph nodes.5.The volume on 18F-FDG PET-CT was close to the actual measure than that of MRI. Objective To observe the growth of rabbit VX2 nasopharyngeal carcinoma(NPC)primary lesion and the invasive distance of tumor growth under the microendoscope,and to study characteristics of VX2 nasopharyngeal carcinoma primary lesion on 18F-deoxyglucose positron emission tomography computed tomography(18F-FDG PET-CT) image.Methods One week After establishment VX2 NPC model,18F-FDG PET-CT,Magnetic resonance imaging(MRI)and anatomy were completed within 48 hours.To observe growth of NPC primary lesion and adjust the invasive area of NPC based CT,MRI,PET-CT images: for the purpose of making pathology diagnoses on specimen obtained from different distance of tumor edge through eyes,we measure MAXSUV of NPC,and delineate tumor volume on PET-CT and MRI images.Results 1.VX2 rabbit NPC primary lesion had invasively grown to invade the surroundings tissues and organs,such as parapharyngeal spaces,Nasal cavities,0ropharynx,skull base,clivus,infratemporal fossa,cavernous and so on;2.The data was obtained on 360 specimens from four directions of 30 rabbits NPC,the distance of distal spread of NP tumor under microendoscope were 22 positive specimens in 0.5cm from tumour edges,in rate of 18.33%(22/120);6 positive specimens＞0.5cm and≤1cm from tumour edge,in 5%(6/120);1 positive specimens in＞cm and≤1.5cm from tumour edge,in 0.8%(1/120);3.There are 9 rabbit clivus were invaded by cancer cell in total 30 VX2 NPC rabbits,30%(9/30).CT found 1(11.1%),MRI found 5(55.6%)and PET-CT found 6(66.7%),so relatively PET-CT can found more invasive clivus cases;4.MAX SUM was negatively correlated with NPC volume(r=-0.426),but not relatived to neck node metastasis and distance metastasis;5.The volume based on 18F-FDG PET-CT images was smaller than that on MRI image,but there were not significantly difference between them. However,we discovered that14 cases volume had changed more than 50%between PET-CT and MRI images,1 increased and 13 decreased.Conclusion:1.Characteristics of invades growth in VX2 NPC is similar to human NPC;2.VX2 NPC' s clinical target volume(CTV) was mostly in 0.5cm from tumor edge confirmed microendoscope;3.For detection clivy invase,PET-CT can be found more cases than MRI,but PET-CT hasn't obviously advantage.4.MAX SUM of VX2NPC isn't a predict index to detect neck lymph node metastasis and distance metastasis.5.The volume based delineated on PET-CT was smaller than that based on MRI and some case volume had obviously changed between two checks.Thought there was no significantly different from them,it has huge different on tumor range between PET-CT and MRI.