Differentiation of glioblastoma from solitary brain metastasis using apparent diffusion coefficient values and MR imaging characteristics

Objective: To evaluate minimum intratumoral apparent diffusion coefficient (ADC) values, peritumoral ADC values, and magnetic resonance imaging (MRI) characteristics in the differentiation of glioblastoma (GBM) from solitary brain metastasis. Materials and Methods: A cross-sectional study with retrospective review of MRI comparing minimum intratumoral ADC values, peritumoral ADC values, and pre-operative MRI characteristics of 22 patients with GBM and 19 patients with solitary brain metastasis was performed. Results: The minimum intratumoral ADC values and normalized minimum intratumoral ADC ratio of GBM of 621.64±145.68 ×10^-6 mm^2/second and 0.84±0.19, respectively, were significantly lower than the values of solitary brain metastasis of 725.75±181.64 ×10^-6 mm^2/second and 0.99±0.23. There was no statistically significant difference of minimum peritumoral ADC values and normalized minimum peritumoral ADC ratios between GBM and solitary brain metastasis. MRI characteristics, such as shape of tumor, presence of susceptibility foci, and restricted diffusion of GBM and solitary brain metastasis were significantly different. Conclusion: The minimum intratumoral ADC value was useful in differentiation between GBM and solitary brain metastasis. The minimum intratumoral ADC value and the normalized minimum intratumoral ADC ratio of GBM were significantly lower than those in solitary brain metastasis. Moreover, some MRI characteristics were in favor of differentiation between these two tumor entities including shape of tumor, presence of susceptibility artifact, and restrict diffusion.