| Background and PurposeGlioma is one of the most common primary intracranial neoplasms.Noninvasive assessing tumor grade and heterogeneity preoperatively are critical to selecting treatment protocol and evaluating prognosis.Diffusion kurtosis imaging(DKI)is an accurate technique in reflecting microstructure of tissue based on the diffusional non-Gaussianity of water in vivo.Our aim was to explore the value of pretreatment in DKI and conventional diffusion weighted imaging(DWI)in grading and evaluating the prognosis of patients with gliomas retrospectively.Materials and MethodsForty-eight consecutive patientswith gliomas underwent pretreatment DKI and DWI examination between September 2014 and December 2015.Diffusion parameters,including mean diffusivity(MD),fractional anisotropy(FA),mean kurtosis(MK),radial kurtosis(RK),axial kurtosis(AK)and minimum apparent diffusion coefficient(minADC),were assessed by region of interest defined in the solid part of tumor,and were normalized to the contralateral normal-appearing white matter.Tissue samples were underwent immunohistochemical staining of Ki-67.All the parameters were compared by using an independent T test and one-way ANOVA.The diagnostic efficiency of the each parameter in grading gliomas and 15-months prediction of survival(over 15-months:long survival group or less 15-months:short survival group)for patients with high-grade gliomas was assessed by a receiver operating characteristic curve and the area under the receiver operating characteristic curve(AUC).The favorable prognostic imaging biomarkers were further analyzed by using a Kaplan-Meier method with log-rank test.Correlations among each imaging parameter,Ki-67 labeling index(LI)and survival were analyzed by a Pearson and Spearman methods.Results DKI parameters(MK,AK,RK)and minADC showed significantly differences between low-grade and high-grade gliomas(P<0.001),as well as the lower gliomas(P<0.05).The significantly difference for MD was only found between low-grade and high-grade gliomas(P<0.05).FA did not show significantly difference between different grades of gliomas(P>0.05).MK with higher AUC for differentiating low-grade and high-grade gliomas(0.954)and the lower gliomas(0.861).The DKI parameters of the long survival group was significantly lower than that of the short survival group(P<0.001),while the mean minADC of the long survival group was significantly higher than that of the short survival group(P=O.002).Among these imaging parameters,the optimal cutoff value of MK(0.679)provided the best combination of sensitivity(87.5%)and specificity(82.4%)for differentiation of patients with long survival from those with short survival.The difference in the prognosis between two groups divided by using this cutoff value was significant(P<0.01,log-rank analysis).The Ki-67 LI was significantly higher in HGGs than that in LGGs(21.64%±13.08%vs.4.71%±3.67%,P<0.001).Ki-67 LI were evidently lower in the long survival group than those in the short survival group(30.00 ± 12.79 vs 15.38 ±9.50,P=0.002).Ki-67 LI was significant positive correlated with DKI parameters(P<0.001)and negative correlated with minADC(P<0.001),respectively.ConclusionThe abilities of DKI parameters(especially MK and RK)in differentiation low-grade and high-grade gliomas as well as the lower gliomas are greater than those of conventional diffusion imaging.Both DKI and conventional DWI have the potential to predict survival for the patients with high-grade gliomas.The preoperative DKI parameters,especially MK,show a higher sensitivity and specificity than conventional DWI for evaluating prognosis. |
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