| Objective:To investigate the diagnostic value of multiple b-values diffusion weighted imaging(DWI)in predicting the genotypes of isocitrate dehydrogenase1(IDH1)in WHO grade ?-? astrocytomas.Methods:A retrospective analysis of 32 cases of WHO grade ?-? astrocytoma patients with IDH genetic information and image information from January 2015 to December 2018 was done in our hospital.All patients underwent routine MRI scan and multiple b-value DWI scan before operation.The images were clear and complete.After the pathological diagnosis of astrocytomas,the specimens were made into tissue wax blocks and sent to special inspection agency;Sanger gene sequencing analysis was performed to obtain a complete and clear diagnosis result of IDH gene.The original image was imported into the GE AW4.4 workstation,pseudo-color maps of Aquaporines related diffusion coefficient(AQP-ADC),true diffusion coefficient(D),perfusion related diffusion coefficient(D*)and perfusion fraction(f)were obtained by MADC and AQP post-processing software.Under the supervision of two experienced imaging doctors,the author manually mapped the region of interest(ROI)in the parenchymal parenchyma(the most prominent area of ??enhancement)and the normal facial parenchyma in the same layer.Parameters of AQP-ADC,D,D*,f value were therefore obtained,these calculated parameters were calibrated(the tumor parenchyma parameter value divided byIV the contralateral normal brain parenchyma parameter value)to obtain relative AQP-ADC,(rAQP-ADC),relative D(relative D*),relative f(rf)and etc.The obtained data were statistically analyzed by social science statistical software package(SPSS 19.0).A t-test was used to analyse the difference of parameters between IDH mutation group and IDH wild-type group in WHO grade ?-? astrocytomas.Statistically significant parameters??were plotted to receiver operating characteristic(ROC)curves,then calculate threshold,sensitivity,and specificity.Results:(1)In WHO grade ?-? astrocytomas,the mutation rate of IDH is 53.13%;(2)In WHO grade ?-? astrocytomas,the IDH mutation group patients are generally younger than the IDH wild group,while there is no significant difference between genders.(3)In WHO grade ?-? astrocytomas,the rD value of IDH mutation group was higher than IDH wild type,D*,rD*,rf value was lower than wild type,the difference was statistically significant(P <0.05),no statistic significance was observed in the other parameters(P>0.05).The area under the ROC curve of the rD was 0.706,when the rD value was 1.839,the sensitivity was 64.71%,and the specificity was 80.00%,The area under the ROC curve of the D* was 0.814,when the D* value was 0.00267,the sensitivity was 88.24%,and the specificity was 66.67%,The area under the ROC curve of the rD* was 0.759,when the rD* value was 0.969,the sensitivity was 58.82%,and the specificity was 93.33%,The area under the ROC curve of the rf was 0.710,when the rf value was 1.875,the sensitivity was 88.24%,and the specificity was 53.33%.Conclusion:Multiple b-value DWI has certain application value for diagnosis of IDH genotype in WHO grade ?-? astrocytomas,in which the D* of the tumor has the largest area under the ROC curve,which means it has the highest diagnostic value for IDH gene mutations.The rD* value of tumor has the biggest specificity in diagnosis of genotypes.As a new technology of magnetic resonance imaging,multi-b value DWI can reflect the microstructural changes of lesions objectively through quantitative parameters,which can provide more imformation in preoperative non-invasive diagnosis of WHO grade ?-? brain glioma IDH genotyping before surgery.It has important clinical significance for treatment options and prognosis evaluation. |
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