| Objectives:1.Establish A model of inflammatory hyperplasia lymph node and metastatic lymph node to explore the optimal time of lymph node growth.2.To investigate the relationship between the diffusion sensitivity factor(b value)and the DWI image SNR(SNR),to find the best b value with best quality of the image.3.To investigate the value of the apparent diffusion coefficient(ADC)value and the relative apparent diffusion coefficient(rADC)value in the diagnosis of popliteal node metastasis in VX2 tumor rabbits.4.Through dynamic enhanced MRI,discusses the first minute increase rate ST1%,Tmax,maximum rate of reinforcement SImax%,peak enhancement rate Emax and TI-Time curve of in differentiating inflammatory hyperplasia and the value of metastatic lymph nodes.Methods:1.establish a inflammatory hyperplasia lymph node model and metastatic lymph node model in rabbits,and to explore the optimal time of lymph node growth.An average 32 New Zealand white rabbit were randomly divided into 2 groups,respectively,in the right thigh shares outside the rectus muscle injection of yolk emulsion and VX2 cell suspension,injection of yolk emulsion set up once a day on the third day routine MRI scan,injection of VX2 cell suspension group on the seventh day every 2 days do a routine MRI scan,observation record the change of the popliteal fossa lymph node size,began to appear smaller or necrosis in lymph nodes removed do pathological examinatio.2.MRI scansWith German SIMENS 1.5T MRI scanner AVANTO,MRI(T1,T2 scanning,diffusion weighted imaging(DWI)scan(b=0s/mm2,200 s/mm2,400 s/mm2,600 s/mm2,800s/mm2,1200 s/mm2,noncontrast and dynamic contrast-enhanced MRI scans)was performed in 10 New Zealand rabbit s with popliteal fossa VX2 tumor metastasis lymph node and 10 New Zealand rabbits with popliteal fossa inflammatory hyperplasia of reactivity lymph node.Observe the morphological characteristics of two groups of lymph nodes,find the best b value with highest SNR in this study,analyzed two groups of lymph node apparent diffusion coefficients(ADC),the relative apparent diffusion coefficient(rADC)values and DCE MRI hemodynamic parameters(SI1%1 min increase rate,Tmax,maximum rate of reinforcement Slmax%,and time-signal curve peak enhancement rate).3.Specimen collection and Pathological examinationAfter the scanning,the two groups of rabbits were dissected,and the complete lymph nodes were taken out,and the measured size was put into the labeled formalin liquid bottle and Sent to Pathological examination.4.Data analysis and statisticsSPSS 23.0 statistical software was used for all data,and the size of lymph node and metastasis group in the inflammatory group before and after the model was tested by self-controlled paired t.Diffusion weighted imaging with different b values signal-to-noise ratio SNR using single factor analysis,two groups of ADC values,rADC value of lymph node and dynamic enhanced imaging measurement parameter values to normality test,accord with normal distribution are two independent samples t test,if does not conform to the using Wilcoxon test.Establish ADC values,the receiver-operating characteristic(ROC)curve for the ADC value and rADC identify inflammatory hyperplasia and tumors lymph node metastatic lymph nodes of threshold,and calculate the corresponding threshold value under the diagnostic sensitivity and specificity of malignant lymph nodes;Time-signal is checked by chi-square after proper combination;P<0.05 was considered statistically significant.Results:1.The modeling results of inflammatory hyperplasia lymph nodes and metastatic lymph nodes.In this experimental inflammatory hyperplasia group,9 inflammatory hyperplastic lymph nodes were obtained,all of which were located in the right popliteal fossa,which reached the maximum in the 7th or 7th day.There were 17 metastatic lymph nodes in the tumor metastasis group,9 in the right popliteal fossa,5 in the right iliac artery,and the largest in the 14th or the 2nd day.2.MRI results.In conventional magnetic resonance imaging,the inflammatory lymph nodes are mostly oval,the lymph nodes are edema,the fat margins are blurred,and the surrounding soft tissue is indistinct.Metastatic lymph nodes are mostly round or spherical,with a clear outline.The size of lymph nodes before and after the formation of inflammatory hyperplasia with P= 0.000<0.05,and Z=-2.859b;The lymph node size of the tumor metastasis group was compared with P=0.000<0.05,and Z=-3.920b.Inflammatory lymph nodes and metastatic lymph nodes showed high signal on DWI,P>0.05.DWI image SNR can within a certain range increased with the increase of b value increases,when b = 800 s/mm2,when b>800 s/mm2,with the increase of b value,SNR gradually decline.the average ADC value of the inflammatory lymph node group was(0.982±0.025)x10-3mm/s2,and the ADC value of the metastatic lymph nodes was(0.769±0.071)x10-3mm/s2.The area under the ADC value curve of inflammatory reactive hyperplasia lymph node and metastatic lymph node was 0.881,the diagnostic threshold was 0.868,the sensitivity was 83%,and the specificity was 79%.the average rADC value of the inflammatory lymph node group was 0.782±0.015,and the rADC value of the metastatic lymph nodes was 0.556±0.008,The area under the rADC value curve of inflammatory reactive hyperplasia lymph node and metastatic lymph node was 0.938,the diagnostic threshold was 0.647,the sensitivity was 87%,and the specificity was 83%.Inflammatory hyperplasia lymph node SI1%was less than tumor metastatic lymph node,P<0.05,and the diagnostic threshold was 412.9,with a sensitivity of 96%and specificity 93%.There was a difference in Tmax,Emax,SImax%of two groups of lymph node,P>0.05.SI-Time curve inflammatory hyperplastic lymphadenopathy is type ? more,and metastatic lymph nodes in type ?,type ? curve is boyth seen in inflammatory hyperplastic lymph nodes and lymph nodes metastasis,?2= 31.175,P = 31.175<0.05.Conclusion(s):1.Injection of egg yolk latex and VX2 tumor suspension can successfully produce the inflammatory hyperplasia model of rabbit popliteal node and metastatic lymph node model,The difference of lymph node size before and after the model was statistically significant.The lymph nodes of the tumor group were larger than those of the inflammatory group,but the difference was not statistically significant.The lymph nodes in the inflammatory hyperplasia reached the maximum in 7±1 days,then the inflammation subsided,and the lymph nodes began to shrink.The lymph nodes of the tumor metastatic group reached with the large in 14±2 days,and then cystic degeneration and necrosis began to appear in the lymph nodes.The establishment of inflammatory hyperplasia lymph node model and metastatic lymph node model contributes to the experimental study of inflammatory lymph nodes and metastatic lymph nodes.2.Inflammatory hyperplastic lymph node metastasis lymph node and on DWI were high signal on the can,there was no statistically significant difference,When b =800 s/mm2,this study DWI image can obtain highest SNR(image SNR comparing two P values<0.05),the rADC value have more area under the ROC curve than ADC values,sensitivity,specificity of diagnosis of metastasis lymph nodes were improved.rADC is more accurate in identifying inflammatory lymph nodes and metastatic lymph nodes than ADC values,which can be used as a rapid and noninvasive method for identifying malignant tumor lymph node metastasis.3.Dynamic enhanced MRI can provide hemodynamic characteristics of lymph nodes,SI-Time curve combined with dynamic enhancement parameters can help to identify the inflammatory hyperplasia lymph nodes and metastatic lymph nodes. |
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