Role of dti in differentiating high grade glioma and solitary metastasis

Context: Diffusion tensor imaging (DTI) is an advanced MR technique that describes the movement of water molecules by using two metrics, mean diffusivity (MD), and fractional anisotropy (FA), which represent the magnitude and directionality of water diffusion, respectively. We hypothesize that alterations in these values within the tissue surrounding brain tumours reflect combinations of increased water content and tumor infiltration and that these changes can be used to differentiate high-grade gliomas from metastatic lesions. Aim: To differentiate between vasogenic and infiltrative edema using FA and MD values. Settings and Design: This is a prospective study, conducted in the Department of Radiodiagnosis and Imaging, Kasturba Medical College, Manipal. Number of study subjects were 30 patients. Methods and Material: • Imaging was performed on a 1.5T Philips Achieva MRI machine using a head coil. • DTI images was then acquired to allow comparison of the results. Statistical analysis used: Student independent t-test. Results: For perilesional FA values, p-value is 0.003, statistically significant for differentiating glioma and metastasis. The cut-off value is 0.174, above which is high grade glioma and below is metastasis. Sensitivity is 78.6 % and specificity is 73%. For perilesional MD values, p-value is 0.138, not statistically significant for differentiating glioma and metastasis. Conclusion: The FA value changes surrounding gliomas, can be attributed not only to increased water content, but also to tumor infiltration.