Intravoxel Incoherent Motion Diffusion Weighted Imaging In The Differential Diagnosis Between High-grade Gliomas And Brain Metastases

Objective:To investigate the value of intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) in the differentiation of high-grade gliomas and brain metastases.Materials and Methods:The conventional MR imaging, contrast-enhanced MR imaging and IVIM-DWI were performed in 13 patients with high-grade gliomas and 17 cases with brain metastases before any treatment performed. The IVIM sequence was performed with 8 b values from 0 s/mm2 to 1000 s/mm2, all of the data fitted to the bi-exponential model. The diffusion constant D values and the pseudodiffusion coefficient of perfusion D* values of tumor parenchyma, peritumor edema region and the contralateral normal white matter region were measured, and then the relative D value (rD) and the relative D* value (rD*) in tumor parenchyma and peritumor edema region were calculated. All parameters were compared within the three regions of both tumor groups, and compared between the two groups in the corresponding region. It was defined as significant difference when P value was lower than 0.05. Receiver operating characteristic (ROC) analyses were performed to determine the optimal thresholds for differentiating the high-grade gliomas from the brain metastases by every parameter. In addition, the sensitivity, specificity, and area under curve (AUC) for identifying high-grade gliomas were calculated. Results:There were significant differences in D value and D* value of high-grade gliomas and D value of brain metastases between tumor parenchyma, peritumoral edema region and the contralateral normal white matter (P<0.05). The D* values of tumor parenchyma were statistically different from that of peritumoral edema region and the contralateral normal white matter in metastasis(P<0.05). There wasn’t significant difference in D* value between peritumor edema region and the contralateral normal white matter (P>0.05). There were significant differences in rD value and rD* value of high-grade gliomas and brain metastases between tumor parenchyma and peritumoral edema region (P<0.05). The D* value and rD* value of high-grade gliomas in tumor parenchyma and in peritumoral edema region were statistically different from that of brain metastases (P<0.05). ROC analysis showed that the diagnostic value of D* and rD* in tumor parenchyma and in peritumoral edema region were relatively high, and the D* value in peritumoral edema region was superior (AUC=0.84, P=0.000, the sensitivity was 84.6%, the specificity was 88.2%), the cutoff value was 5.12 x 10"3mm2/s. There wasn’t significant difference in the D value and rD value of tumor parenchyma and peritumor edema region and in the D value and D* value of the contralateral normal white matter between the two groups(P>0.05). Conclusion:IVIM DWI might be a noninvasive methods of differentiation brain metastases and high-grade gliomas.