| Part 1 Dynamic Assessment of Benign Lymph Nodes after Carbogen inhalation using Blood Oxygen Level-dependent MRIObjective To explore the dynamic changes of benign lymph nodes after Carbogen inhalation by blood oxygen level-dependent(BOLD)MRI.Methods The benign lymph node model in 20 New Zealand rabbits was established in the popliteal fossa and randomly divided into two groups,control group(Co良)(n=4)and Carbogen gas group(Ca良)(n=16).Ca良 group undergone BOLD-MRI at the baseline(R2*ca0良),after 10 minutes and 20 minutes Carbogen inhalation(R2*Ca10良,R2*Ca20良),and after 10 minutes and 20 minutes air inhalation(R2*Ca30良、R2*Ca40良).Co良group undergone BOLD-MRI 5 times at the same time when breathing air freely(R2*Co0良、R2*Co10良、R2*Co20良、R2*Co30良、R2*Co40良).The lymph nodes were resected for pathological analysis after the MR examinations.The central level of the lymph node in BOLD imaging were selected for image analysis of each lymph node,the area of interest outlining the lymph node was conducted and the corresponding R2* value was recorded.Data were statistically analyzed.Results All the tested lymph nodes were benign lymphoid tissue.The R2* values of lymph nodes of Ca良group decreased after 20 minute Carbogen inhalation,and then increased after breathing air again freely.LSD test was used to compare the differences of R2* values,the values of R2*Ca20 良were lower than that of R2*Ca0 良,the difference was significant(P=0.007<0.05),the values of R2*Ca20 良 was significantly lower than that of R2*Ca30 良(P=0.014<0.05),the values of R2*Ca20 良 was significantly lower than that of R2*Ca40 良(P=0.003<0.05),and the difference between R2*Ca0 良、R2*Ca30 良 and R2*Ca40 良 was not statistically significant(P>0.05).There was no significant change of the R2* values of Co良 group(F=0.284,P>0.05).Ca良 group compared with Co良 group,the values of R2*Ca20 良 was significantly lower than that of R2*Co0 良(P=0.011<0.05).The R2* values of the other four times points were not statistically significant(P>0.05).Conclusion The dynamic changes of R2* values of benign lymph nodes after Carbogen inhalation suggest that MRI-BOLD has the potential to monitor the state of oxygenation in tissues.Part 2 BOLD-MRI For Dynamic Assessment of Metastatic Nodes after Carbogen inhalation and The Diagnosis Of Metastatic And Benign Lymphoid Lesions:An Experimental StudyObjective To explore the dynamic changes of metastatic lymph nodesafter inhaling Carbogen by BOLD-MRI,and the value of identifying benign and metastatic lymph nodes.Methods The metastatic lymph node model in 20 New Zealand rabbits was established in the popliteal fossa and randomly divided into two groups,control group(Co恶)(n=4)and Carbogen gas group(Ca恶)(n=16).Ca恶 group undergone BOLD-MRI at the baseline(R2*Ca0恶),after 10 minutes and 20 minutes Carbogen inhalation(R2*Ca10恶,R2*Ca20恶,respectively),and after 10 minutes and 20 minutes air inhalation(R2*Ca30恶、R2*Ca40恶).Co恶 group undergone BOLD-MRI 5 times at the same times when breathing air freely(R2*Co0恶、R2* Co10恶、R2* Co20恶、R2* Co30恶、R2* Co40恶).The lymph nodes were resected for pathological analysis after the MR examinations.The central level of the lymph node in BOLD imaging were selected for image analysis of each lymph node,avoided the necrotic area,draw the substantive area of lymph nodes as the the area of interest,recorded the corresponding R2 * value.Data were statistically analyzed.Measure short-term of lymph nodes in benign and malignant groups,and the change of R2* was calculated as the ΔR2*20-0 value after 20 minutes Carbogen inhalation,The ROC curve was used to analysis the lymph node short-terms,baseline R2*0 andΔR2*20-0 values in benign and metastatic lymph nodes.Results All the tested lymph nodes were metastatic lymphoid tissue.The R2* values of lymph nodes of Ca恶 group decreased after 20 minutes Carbogen inhalation,and then increased after breathing air again freely.LSD test was used to compare the differences of R2* values,the values of R2*Ca20 恶were lower than that of R2*Ca0 恶,the difference was significant(P=0.002<0.05),the values of R2*Ca20 恶 was significantly lower than that of R2*Ca30 恶(P=0.016<0.05),the values of R2*Ca20 恶 was significantly lower than that of R2*Ca40 恶(P=0.005<0.05),and the difference between R2*Ca0 恶、R2*Ca30 恶and R2*Ca40 恶was not statistically significant(P>0.05).There was no significant change of the R2* values of Co恶 group(F=0.708,P>0.05).Ca恶 group compared with Co恶 group,the values of R2*Ca20 恶 was significantly lower than that of R2*Co20 恶(P=0.008<0.05).The R2* values of the other four time points were not statistically significant(P>0.05).The baseline R2*0 value of benign and metastatic lymph nodes was statistically significant(t=-0.64,P=0.53<0.05),the ΔR2*20-0 value of benign and metastatic lymph nodes was statistically significant(t=-6.54,P=0.000<0.05),there was no significant change of short diameters between benign and metastatic lymph nodes(t=-1.52,P=0.15>0.05),and areas under the curve of ROC of the three methods were 0.668、0.803、0.859。Conclusion The R2* value of metastatic lymph node changed dynamically after Carbogen inhalation.The change of R2* value of metastatic lymph nodes was more obvious than that of benign lymph nodes after Carbogen inhalation.The ΔR2*20-0 value has the most meaningful of discriminating lymph nodes in benign and malignant lesions.MRI-BOLD with inhalation of Carbogen gas may be helpful in the differential diagnosis of benign and malignant lymph nodes. |
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