| Purpose:To research the value of discriminating the lesion with radiotherapy by MSCT perfusion on New Zealand white rabbit VX2 nasopharyngeal carcinoma model, evaluate the accuracy of differentiating the lesion by MSCT perfusion according to pathology results, seek a new, applicable method to supply for the distinguishing lesion after radiotherapy by physical and pathological foundation.Materials and Methods:All white rabbits were injected VX2 carcinoma cell suspension in their nasopharynx through the CT guide, the growth information of white rabbit were examined after 2 weeks. The successful white rabbit VX2 nasopharyngeal carcinoma were received the radiotherapy, they were underwent conventional CT and CT perfusion scans in 1 weeks after the end of radiotherapy. All white rabbit were executed for pathology, the lesion were identified on microscopy.Results:22 white rabbits had tumors growth in nasopharynx and enrolled the experiment. The tumors sizes of 22 white rabbits ranged 1.5 from 5cm, the rate of successful New Zealand white rabbit VX2 nasopharyngeal carcinoma were 75.9%(22/29). There had 12 white rabbits with residual, and 10 white rabbits with non-residual according to pathological proof. The mean of MVD in residual white rabbits were significant higher than that of in non-residual (P<0.05). The means of BF, BV, and PS in residual white rabbits on CT perfusion were higher than that of in non-residual (P<0.05), the mean of MTT in residual white rabbits were statistical lower than that of non-residual((P <0.05). There had positive correlation between BF, BV, PS and MVD, and negative correlation between MTT and MVD.Conclusion:For New Zealand white rabbits VX2 carcinoma and nasopharyngeal carcinoma in human being have some same characters, such as hyper-vascular, indifferentiated squamous cell carcinoma, so the model of rabbit VX2 nasopharyngeal carcinoma is near to the'idealization of animal model criteria. The CT perfusion may assist to differentiate the character of lesion with nasopharyngeal carcinoma after radiotherapy for correlation between CT perfusion parameters and MVD, and will apply with information on human nasopharyngeal carcinoma after radiotherapy in the future. Objective:To investigate the differentiation of lesion with human nasopharyngeal carcinoma with radiotherapy by CT perfusion on virtue of results on animal experiments, analyzed the character of different lesion with nasopharyngeal carcinoma on CT perfusion, and assess the value of CT perfusion in clinic application and predicting the prognosis of nasopharyngeal carcinoma after radiotherapy.Material and Methods:174 patients with T2-T3 nasopharyngeal carcinoma after radiotherapy were enrolled in the study. All patients were received the conventional CT, CT perfusion, and pathology examinations. All patients were dived into two groups with pathologic finding as reference standards:residual groups and non-residual groups. The CT perfusion parameters, time-density curves (TDC), and MVD were recorded in all patients. The means of CT perfusion parameters between residual and non residual patients with NPC after RCT were compared by t-test for independent samples, the constituent ratio of TDC between residual and non residual were compared by X2 test. The correlation between CT perfusion parameters and MVD were compared rank correlation.Results:"Fast rise and slow down" and " fast rise and fast down" of TDC type were always found in residual patients with nasopharyngeal carcinoma after radiotherapy, "flat" and " slow rise and slow down" of TDC type were often detected in fibrosis, constituent ratio of TDC type had statistical difference between two groups (P<0.01). The mean of MVD in residual white rabbits were significant higher than that of in non-residual (P<0.05). The means of BF, BV, and PS in residual patients with nasopharyngeal carcinoma after radiotherapy on CT perfusion were higher than that of in non-residual (P<0.05), the mean of MTT in residual human nasopharyngeal carcinoma were statistical lower than that of non-residual (P<0.05). There had positive correlation between BF, BV, PS and MVD, and negative correlation between MTT and MVD.Conclusion:patients with post radiotherapy nasopharyngeal carcinoma have difference types of TDC of MSCT perfusion imaging, and will be helpful to differentiation between residual and non-residual patients. The CT perfusion may assist to differentiate the character of lesion with nasopharyngeal carcinoma after radiotherapy for correlation between CT perfusion parameters and MVD, and will apply with information on human nasopharyngeal carcinoma after radiotherapy. Objective To explore the accuracy of detecting residual after nasopharyngeal carcinoma (NPC) radiation therapy (RCT) by cutoff value of CT perfusion parameters.Materials and Methods This study was approved by the institutional review board of oncology hospital, and informed patient consent was obtained before study participation according to institutional and native guidelines.186 patients after NPC radiation therapy underwent CT perfusion. According to pathology, all cases were divided into two groups, local residual group and non-residual group.186 patients had 89 women,97 men, age range,22-61 years; mean age,43.2 years. On transverse images of the nasopharynx, the transverse image was selected for CT perfusion study when nasopharynx structures, internal carotid, and internal vein were clearly visualized. All patients underwent multi-detector CT scanner (LightSpeed ultra; GE Medical Systems). For initial localization of the lesion, a CT scan (120kV,250mAs) from cavernous sinus to alveloa process f maxillary was obtained without contrast medium during a breath hold and no deglutition. This series helped locate the lesion and set four dynamic acquisition slices at the correct level. Then, a 2 cm lesion region was selected for dynamic study in the maximal diameter of the lesion. A dynamic study of the selected area was performed at a static table position. Dynamic images (80kV,80mAs) were then obtained after 5 seconds in the injection of contrast media. A total of 50 ml of nonionic iodinated contrast medium (Ultravist 300, Schering) (300mg of iodine per milliliter) was inject at a rate 3.5 ml/sec through an 18-gauge intravenous cannula. This series provided a total of 340(images.To avoid respiratory motion artifacts, patients were clearly informed of a possible flushing sensation during contrast agent injection. All CT perfusion parameters between residual and non-residual patients with NPC after RCT were statistical analyzed. ROC curves were drawn in significantly statistical CT parameters in residual patients by SPSS 17.0, and helped to find cutoff value in diagnosing local residual.Results In BF, BV, and PS, there were statistical difference between local residual and non-residual change (P<0.05), and had statistical difference in MTT (P<0.05). With ROC curve help, BF, BV, and PS cutoff value was 337.20(ml/100g/min),10.18(100g/min),17.34 (ml/100g/min), sensitivity was 92.6%,96.3%,81.5%, specificity was 76.2%,81%,61.9%, and area under the ROC curve was 0.891,0.938,0.780 in diagnosing the residual patients with RCT, respectively, the optimal threshold value of MTT were not obtained for much more overlap.Conclusion CT perfusion many mirror hemo-dynamics of the various tissues after NPC radiation therapy, and have relative high accuracy in diagnosing the local residual in NPC with Radiation therapy.
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