Ultrasound Microbubbles For Diagnosis Of The Cervical Lymph Node Metastases In Rabbit’s Tongue Cancer

As everyone knows, the tongue cancer has the highest accidence inhuman’s oral and maxillofacial carcinomas, which is almost SCC. Thepatients with tongue squamous carcinomas get the cervical lymph nodeseasily and early and lung metastases at late stage. Once the patients getcervical lymph node metastases, the clinical tumor stage, the plan ofexamination and treatment and the prognosis of the disease will beaffected obviously. Thus it’s necessary for the therapeutic schedule andthe effect enhancement to diagnosis the cervical lymph nodes of thepatients attacked by the tongue cancer as soon as possible. As one kind ofthe common methods for the examination of cervical lymph nodes withtongue carcinoma, Doppler ultrasound has been widely and maturelyapplied in clinical, for the advantages of simple operation, no radiationand noninvasive. However, its litter poor diagnostic sensitivity andspecificity still can’t satisfy the requirement for the diagnosis yet.Ultrasound microbubble (UM) is a kind of emerging products in the fieldof modern ultrasonic medicine, developing rapidly in recent years. UMenhances the resolution of ultrasonic imaging by changing the ultrasoniccharacteristics of diseased tissues and organs, so as to improve theultrasonic diagnostic sensitivity and specificity, which has been thehotspot on the researches in ultrasonic medicine. In this study, we established the large animal model of the tonguecarcinoma and cervical lymph node metastases in the rabbits by the freshintact hepatic VX2tumor tissue and observed the occurred rules of thelymph node metastases. Then we chose the best time to examine the nodesdifferent in character by Doppler ultrasound and microbubbles contrastenhanced ultrasound imaging, in order to make the diagnostic tests forboth. We compared the differences between the ultrasonic images beforeand after the injection of ultrasound microbubbles. The purpose was toevaluate the potential application and diagnostic value of ultrasoundmicrobubbles for the cervical metastatic lymph nodes with tonguecarcinoma.Methods1. To establish the large animal model of tongue carcinoma andcervical lymph node metastasesThe rabbits′fresh hepatic intact VX2tumor tissues were transplantedto the left lateral border of the tongues of30New-Zealand White rabbits,and then the incisions were accurately closed. The rabbits wererandomly divided into1-,3-and5-Week Group by the time of death(n=10each). We observed the growth and general shape of the tonguetumor and cervical lymph nodes at the fixed periods. The specimens oftransplanted carcinomas and swelling lymph nodes were examinedgenerally and pathologically after the death, according to which we choosethe appropriate timing for the nodes’ ultrasonic examination.2. Doppler ultrasound and ultrasound microbubble contrast-enhancedimaging of the cervical lymph nodes20New-Zealand White rabbits were transplanted by the intact VX2tumor tissues as above. We made Doppler ultrasound and ultrasoundmicrobubble contrast-enhanced imaging for the cervical lymph nodes according to the results of the establishment. The images were observed toanalysis the ultrasonic characteristics of the reactive and metastatic nodes.Compared to the pathological examination, we made diagnostic tests andROC curves for the methods both. Meanwhile the echo intensity values ofthe metastases were examined both before and after the contrast. Thediagnostic value and potential application of them for neck lymph nodemetastases were evaluated.Results1. The tongue tumors were touched smoothly without ulcer in8rabbits of the1-week group, of which the character was intermediate hard.The bigger and hard tumors with ulcer were touched in9rabbits of the3-week group and the swelling, mobile and soft cervical lymph nodeswere palpable. The bulky tumors with obvious ulcers, even the defect ofthe tongue, were touched in9rabbits of the5-week group and the nodeswere palpable, some of which were hard, uneven-formed and less mobile.The pathological results show that the VX2tumor was PDSCC and grewwell in8rabbits of the1-week group.9rabbits of the3-week group gotthe tumor and6swelling reactive lymph nodes were found in left cervicalarea.9rabbits of the5-week group got the tumor and7got the lymphnodes metastases.25swelling lymph nodes were found in both sides,12were diagnosed the reactive lymph nodes and the rest, all in deep cervicalarea, were metastases.2.19rabbits got tumors and there were53swelling nodes in deepcervical area,24were reactive lymph nodes and29were metastatic bypathology. By Doppler ultrasound,27lymph nodes with high uniformityand clear boundary of cortex and medulla were diagnosed the reactive (5were mistaken) and the rest with uneven form and disordered structurewere the doubtfully metastatic (3were mistaken). By the ultrasound microbubbles imaging,26nodes with the contrast agents almost gatheredin the surrounding vascular were diagnosed the reactions and the rest withthe contrast agents unequally gathered inside were the doubtful metastases(2were mistaken). The diagnostic sensitivity, the specificity and the AURwere83%,92%and0.851of Doppler, which were93%,100%and0.966of ultrasound microbubbles imaging. EI values of post-contrast were69.2±4.01, significantly higher than those of the pre-contrast （38.7±4.18）statistically（P＜0.01）.Conclusion1. We can successfully establish the large animal model of tonguecarcinoma after1week of the intact VX2tumor tissues transplant. Thereare cervical lymph node metastases, at first in deep cervical area, after5weeks of the transplant when the experimental rabbits still have goodliving condition. VX2tongue squamous carcinoma in rabbits is highlysimilar to human, taking the biological behavior and metastaticcharacteristics for examples. Thus this model is considered suitable fortongue cancer and cervical lymph node metastases’ study in the5th weekafter the transplant of VX2intact tumor tissue.2. The cervical lymph nodes in different character have their ownultrasonic imaging characteristics. Doppler ultrasound is simple operationand noninvasive for the diagnoses, while the ultrasound microbubblesimaging is minimally invasive for the injection of contrast material.However, the post can increase the visibility of the metastatic nodes andimprove the diagnostic sensitivity and specificity, so it may provide us anew diagnostic method in clinic. The ultrasound microbubbles imaginghas high diagnostic value and potential application for the cervicalmetastatic lymph nodes from tongue carcinoma.