The Value Of DWI And SWI In Grading Of Gliomas

Objective:To evaluate the effectiveness of diffusion weighted imaging(DWI)and susceptibility weighted imaging(SWI)in the diagnosis of high and low grade gliomas.Materials and Methods: In this study,we retrospectively analyzed 20 patients with different grades of gliomas confirmed by pathology.According to the 2007 WHO classification of tumors of the central nervous system,the patients were divided into high-grade group(10cases)and low-grade group(10cases).All patients were underwent MRI,DWI,SWI and enhanced MRI before surgeon with Siemens Magnetom Trio A Tim 3.0T MRI.Combined with MRI enhanced scan,T1 WI and T2 WI images to determine the parenchyma part.(1)We measured Minimum apparent diffusion coefficient values(ADCmin)of tumor parenchyma and contralateral brain parenchyma in ADC images of DWI(b=1000,2000,and 3000 s/mm2)of different b values.(2)We calculated the ratio of ADCmin between the tumor parenchyma and contralateral normal brain,relative ADCmin(rADCmin).(3)Then using independent sample t-test analysised whether each parameterADC value of high-and low-grade group had statistical significant.After drawing the ROC curve of each parameter value.(4)Then using independent sample t-test analysised the difference of ITSS score between high and low grade group.The correlation between ITSS score and histological grading of glioma was analyzed by Spearman correlation test.After drawing the ROC curve to identify the optimal threshold of ITSS that yielded the best combination of sensitivity and specificity,to distinguish high-from low-grade gliomas.(5)We combined DWI and SWI to analyze the sensitivity and specificity in the diagnosis of glioma.Results :(1)With the increase of b values,the DWI images of high-grade gliomas showed high signal in the lesions,while most of the low-grade glioma DWI images showed that the lesions were reduced,and showed low signal.(2)In three different b values conditions,the level of glioma and the minimum ADC and rADC value were significantly negative correlation,and high values of b(rADCmin3000,r=-0.8172,P < 0.0001)with the highest absolute value of r value,shows that the maximum correlation.(3)When b value was the same,the ADCmin and rADCmin values decreased with the increase of glioma grade,and the ADCmin value was the highest at b=3000s/mm2.(4)Comparison of ADCmin values between high-and low-grade groups,b=1000,b=2000 and b=3000(s/mm2)group were statistically significant(P<0.05),There was no significant difference in rADCmin value between b=1000,b=2000 and b=3000(s/mm2)in the high-and low-grade group(P>0.05).(5)The most effective diagnostic rADCmin(b=3000s/mm2).(6)There was a significant difference in ITSS score between different grades of gliomas(t=8.497,P=0.000),and both of them were highly correlated(r=0.8947,P<0.001).When the ITSS score threshold was set to 1,the sensitivity and specificity of the diagnosis of high-grade gliomas were 90.91% and 88.89%,respectively.(7)The sensitivity of the two indexes combination was 100%,and the specificity was 90%,which was higher than that of each index.Conclusion:(1)The ADCmin value and rADCmin value of the DWI parameters were significantly different between the high and low grade gliomas,which was helpful to the grading of glioma,and the value of rADCmin(b=3000s/mm2)was the most significant in the diagnosis of gliomas(2)SWI was helpful to the grading of glioma,and the ITSS score and pathological grade were positively correlated.(3)DWI and SWI,as a commonly used functional magnetic resonance imaging technology,can be used to improve the efficiency of the classification of gliomas,which is an important supplement to conventional MRI.