| This study want to establish Walker-256transplatation tumor Model in SD Rats and evaluated tumor hypoxia by R2*a,△R2*detected by BOLD-MRI method using3.0Tesla clinic MRI equipment and Multi-echo FPGR sequence; to explore the correlation of R2*a,△R2*of Walker-256tumor with pathologic markers of angiogenesis(MVD,VEGF,ICD) and hypoxia endogenous markers (HIF-1α,CAⅨ; to discuss the correlation of R2*a,△R2*of Walker-256tumor with hypoxia markers(HV,HV%,SUVmax) evaluated by18F-FMISO PET/CT examination; and to evaluate the feasibility of monitoring the change of tumor re-oxygenation after a single dose irradiation by BOLD-MRI, in the end.Part Ⅰ The R2*Signal Change of Murine Walker-256Tumor after Inhaling Carbogen detected by BOLD-MRI:A Preliminary StudyObjective:To establish Walker-256transplatation tumor Model in SD Rats, and explore the feasibility of detecting the R2*signal changes on murine Walker-256tumor after inhaling Carbogen by BOLD-MRI.Materials and Methods:Walker-256tumor cell implanted subcutaneously in right lower abdomen of95female SD rats(160-180g). MRI scan was performed on the tumor-forming rats when the maximum diameter of tumor reach1-3cm, using a3.0Tesla MR system (Signa HDx,GE) equipped with a3inch animal surface coil. BOLD-MRI was done by using a Multi-echo SPGR sequence twice:inhaling air and10minute after inhaling Carbogen. All images were transfered to GE ADW4.3workstation, then a baseline R2*(R2*a)and R2*(R2*b) after inhaling Carbogen of tumor was calculated using R2Star analysis software and△R2*was calculated through "△R2=R2*b-R2*a", meanwhile the volume of tumor were calculated as well. The difference of R2*signal pre and post the inhaling of Carbogen was compared with a paired t test, Pearson correlation was calculated between R2*a,△R2*and the volume of tumor, respectively. The correlation between R2*a and△R2*were also assessed by Pearson correlation analyses. The discrepancy of the volume and R2*a were compared across two groups with different change direction ofAR2with Wilcoxon test.Results:68of95female SD rats formed the tumor (71.57%). Mean△R2*decreased significantly (-2.26±3.90) from41.18±22.29S-1during breathing air to38.91±21.35S-110min after inhaling Carbogen(P=0.00).△R2*was inversely correlated with R2*(r=-0.32, P=0.02). The R2*a was not well correlated with volume of tumor, but△R2*(r=0.35, P=0.02). No significant differences of volume and R2*a were detect across two groups with various change direction of△R2*(p=0.076, p=0.11).Conclusions:BOLD-MRI can detect the R2*signal change of murine Walker-256tumor pre and post the inbreathing of Carbogen. The R2*decrease significantly after inhaling Carbogen, however, the individual variation was remarkable. PartⅡ R2*Signal of BOLD-MRI Correlated to Angiogenesis and capillary vessel Structure on Murine Walker-256Tumor:A Preliminary StudyObjective:To explore the relationship between R2Signal of BOLD-MRI and Markers of Angiogenesis as well as vascular structure (MVD, ICD, VEGF) on murine Walker-256tumor.Materials and Methods:33tumor-bearing female SD rats were examined by a3.0Tesla MR system (Signa HDx, GE) equipped with a3inch animal surface coil, when the maximum diameter of tumor reached1-3cm. BOLD-MRI was done by using a Multi-echo SPGR sequence twice:inhaling air and10minute after inhaling Carbogen. Images were transfered to the GE ADW4.3workstation. Then a baseline R2*(R2*a) and R2(R2*b) after inhaling Carbogen of tumor was calculated using R2Star analysis software and△R2*was calculated through "AR2*=R2*b-R2*a". Rats were killed by cervical dislocation and the tumors were resected after MRI examination immediately. Hematoxylin and Eosin staining and immunohistochemistry (CD34,VEGF) were performed and the score of MVD,ICD and immunohistochemistry intensity index of VEGF were calculated. Pearson correlation was calculated between R2a,△R2*and MVD, ICD, VEGF, respectively. The correlation within MVD, ICD and VEGF were also calculated by Pearson correlation analyses.Results:All33rats were performed MRI examination, but only29murine data fitted the inclusive criterion. MVD of tumor was well correlated with VEGF (r=0.58, p=0.03), But no correlation were observed between R2*a,△R2*and MVD,ICD,VEGF.Conclusions:No obvious correlation between R2*a,△R2*and angiogenesis as well as vascular structure on murine Walker-256tumors were founded. PartⅢ R2*Signal of BOLD-MRI Correlated to HIF-la and CAⅨ on Murine Walker-256Tumor:A Preliminary StudyObjective:To explore the relationship between BOLD-MRI and hypoxia endogenous markers (HIF-1α,CAⅨ) in murine Walker-256tumor.Materials and Methods:33tumor-bearing female SD rats were examined by a3.0Tesla MR system (Signa HDx, GE) equipped with a3inch animal surface coil, when the maximum diameter of tumor reached1-3cm. BOLD-MRI was done by using a Multi-echo SPGR sequence twice:inhaling air and10minute after inhaling Carbogen. Images were transfered to the GE ADW4.3workstation.then a baseline R2*(R2*a) and R2(R2b) after inhaling Carbogen of tumor was calculated using R2Star analysis software and△R2*was calculated through "△R2*=R2*b-R2*a". Rats were killed by cervical dislocation and the tumors were resected after MRI examination immediately. Hematoxylin and Eosin staining and Immunohistochemistry (HIF-1α,CA Ⅸ) were performed and the immunohistochemistry intensity index of HIF-1α,CAⅨ were calculated. Pearson correlation was calculated between R2a,AR2and HIF-la,CAⅨ respectively. The correlation within HIF-la,CAⅨ and correlation between MVD,ICD,VEGF and HIF-1α,CAⅨ were also calculated by Pearson correlation analyses.Results:All33rats were performed MRI examination, but only29murine data fitted the inclusive criterion. R2*a,△R2*of tumor were well correlated with CAⅨ, But no correlation were observed between R2a,AR2with HIF-la and no correlation were observed between HIF-laand CAⅨ. Obvious correlation were found between ICD and HIF-1α,CAⅨ; but no correlation between MVD,VEGF and HIF-1α,CAⅨ.Conclusions:R2*a,△R2were obvious correlation with CA Ⅸ on murine Walker-256tumor, but no correlation with HIF-1α. Part Ⅳ A Contrast Study of Hypoxia Evaluation in Murine Walker-256Tumor by BOLD-MRI and18F-FMISO PET Objective:To explore the feasibility of BOLD-MRI in evaluating hypoxia of murine Walker-256tumor compared to18F-FMISO PET hypoxia imaging.Materials and Methods:13tumor-bearing female SD rats were examined by a3.0Tesla MR system (Signa HDx, GE) equipped with a3inch animal surface coil, when the maximum diameter of tumor reached2-5cm. BOLD-MRI was done by using a Multi-echo SPGR sequence twice:inhaling air and10minute after inhaling Carbogen. Images were transferred to the GE ADW4.3workstation.then a baseline R2*(R2*a) and R2*(R2*b) after inhaling Carbogen of tumor was calculated using R2Star analysis software and△R2*, AR2*%was calculated through "AR2*=R2*b-R2*a,△R2*%=△R2*/R2*a×100%". All rats then were examined by PET/CT in18-22hours after MRI examination. Data were collected twice:2hours,4hours after18F-FMISO (22.2-29.6MBq) injected through caudal vein. All images were transferred to Siemens Syngo workstation. Parameters (SUVmax, TMRmax, HV, HV%) were calculated using TrueD software. After MRI and PET/CT examination, rats were killed by cervical dislocation and the tumors were resected immediately. Hematoxylin and Eosin Staining and Immunohistochemistry (CD34,VEGF,HIF-1α,CAⅨ) were performed and the score of MVD and immunohistochemistry intensity index of VEGF,HIF-la,CAⅨ were calculated. The difference of R2*signal pre and post the inhaling of Carbogen was compared with a paired t test, The difference of SUVmax (tumo、muscle)、TMRmax、HV detected in2hours,4hours after18F-Fmiso injected was compared with a paired t test. R2*a, AR2*,△R2*%and SUVmax, HV, HV%of tumor were assessed by Spearman correlation analyses. Meanwhile, SUVmax,HV,HV%and MVD、VEGF、HIF-1α、CAIX of tumor were also assessed by Spearman correlation analyses.Results:Only10rats finished all MRI, PET/CT, pathology examinations and data fitted the inclusive criterion.△R2*of tumor decreased significantly after10min inhaling Carbogen (P=0.00). There were significant difference on SUVmax(muscle),TMRmax and HV of tumor between2hours’and4hours’groups (p=0.01,0.00,0.02), but no difference was found on SUVmax(tumor) between two groups (p=0.39).△R2*%of tumor was obviously correlated with SUVmax, HV, HV%of tumor detected on4hours after18F-FMISO injected, but no2hours. R2*a and△R2*of tumor were no correlation with SUVmax, HV, HV%of tumor detected neither2hours or4hours after18F-FMISO injected. And no significant correlation were also found between SUVmax, HV, HV%on two groups and MVD, VEGF, HIF-1α, CAⅨ of tumor.Conclusion:R2*signal of Walker-256tumor can decrease after rats inhaling Carbogen. Evaluation hypoxia of murine Walker-256tumor by18F-FMISO PET may more suitable on4hours than2hours after18F-FMISO injected.△R2%of tumor may be a ideal surrogate on neoplastic hypoxia evaluating. Part V BOLD-MRI in Murine Walker-256Tumor After a Single Dose Irradiation:A Preliminary StudyObjective:To explore the feasibility of monitoring the change of tumor re-oxygenation after a single dose irradiation by BOLD-MRI.Materials and methods:6tumor-bearing female SD rats (160-180g) were treated with a single dose irradiation (20Gy) by linear accelerator when the maximum diameter of tumor reached1-3cm. BOLD-MRI was performed before radiotherapy and3-4hours,1day,3days after radiotherapy. BOLD-MRI was done by using a Multi-echo SPGR sequence twice:inhaling air freely and10minute after inhaling Carbogen. All images were transferred to GE ADW4.3workstation, then the baseline R2*(R2*a) and R2*(R2*b) after inhaling Carbogen of tumor and muscle were calculated using R2Star analysis software and△R2*was calculated through "AR2*=R2*b-R2*a". Analysis of variance was calculated within changes of R2*a andAR2*on tumors and muscles of four different time point groups. A paired t test was calculated between tumors and muscles of R2*a and△R2*.Results:R2*a of muscle was higher than tumor (p=0.000), but no difference on△R2*between tumor and muscle. Either tumor or muscle were no difference on R2*a and△R2*within four groups of different time point.Conclusion:Although fluctuation of R2*a and△R2*of tumors and muscles after a single dose irradiated have no statistical significance, but BOLD-MRI may be a potential method for monitoring changes of re-oxygenation on tumor and muscle after a single dose irradiation. |
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