Enhancement degree of brain metastases: correlation analysis between enhanced T2 FLAIR and vascular permeability parameters of dynamic contrast-enhanced MRI

Objectives To investigate the correlation between enhancement degrees of brain metastases on contrast-enhanced T2-fluid-attenuated inversion recovery (CE-T2 FLAIR) and vascular permeability parameters of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Methods Thirty-nine patients with brain metastases were prospectively collected. They underwent non-enhanced T2 FLAIR, DCE-MRI, CE-T2 FLAIR, and contrast-enhanced three-dimensional brain volume imaging (CE-BRAVO). Quantitative parameters of DCE-MRI were evaluated for all lesions, which included volume transfer constant (K trans ), rate constant (K ep ), and fractional volume of the extracellular extravascular space (V e ). Contrast ratio (CR) and percentage increase (PI) values of all lesions on CE-T2 FLAIR were also measured. The tumor enhancement degree on CE-T2 FLAIR in relation to CE-BRAVO was visually classified as higher (group A), equal (group B), and lower (group C). Results A total of 82 brain metastases were evaluated, including 31 in group A, 19 in group B, and 32 in group C. The K trans and K ep were negatively correlated with the CR ( ρ = − 0.551, p < 0.001 and ρ = − 0.708, p < 0.001, respectively) and PI ( ρ = − 0.511, p < 0.001 and ρ = − 0.621, p < 0.001, respectively). The K trans and K ep of group A were significantly lower than those of group C (both p < 0.001). No significant difference was found in V e among the groups ( p = 0.327). Conclusions The enhancement degree of brain metastases on CE-T2 FLAIR is negatively correlated with K trans and K ep values, which indicate that vascular permeability parameters may play an important role in explaining the difference in enhancement between CE-T2 FLAIR and CE-BRAVO. Key Points • The enhancement degree on CE-T2 FLAIR was negatively correlated with K trans and K ep values. • The vascular permeability of brain metastasis accounted for the difference in enhancement degree between CE-T2 FLAIR and CE-BRAVO. • CE-T2 FLAIR is useful for detecting brain metastases with mild disruption of the blood-brain barrier.