The Quantitative Relation Between Microvascular Permeability, And Glioma Grading Study

Glioma is the most harmful disease to the human being's health which causes death or disability. Treatment effects and prognosis for patients with glioma mostly depend on the histopathologic grade. Therefore, in clinical practice, it is very important to accurately evaluate the grade of gliomas before the treatment.Contrast agent (CA) bolus injected into the vascular will leak into the surrounding tissues due to the breakdown of blood-brain barrier (BBB) in gliomas, which will result in the increment of intensity of T₁-weighted signal. Based on the fact, the quantitive relationship between microvascular permeability and histopathologic grade of gliomas was discussed by employing T₁-weighted dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) technique in this paper. 28 patients with gliomas were imaged by using T₁-weighted MRI technique. Firstly, all the T₁-weighted images acquired before bolus injection of CA were processed to calculate the baseline T₁ value of artery and tumor area. Extracting the T₁-weighted signals during blous injection of CA and normalized to the baseline, the mean signal intensity-time curves (STC) in ROI of artery and focal area were drawn respectively. Secondly, based on pharmacokinetic analysis, the signal intensity were transformed into concentration of CA and the mean concentration-time curves (CTC) of the two ROI were established. Some semiquantitative and quantitative parameters of microvascular permeability were measured using nonlinear fitting method. Finally, the quantitive relationship between these paremeters and grades of gliomas were established by comparing with histopathology results. Independent-Samples H-test and U-test for these parameters was performed, and a P less than 0.05 for a parameter was considered as statistically significant.The results showed that the initial enhancement rate (E_R), volume transfer constant (K^trans), and size of the extravascular extracellular space (V_e) all can be used to distinguish between the low and the high grade gliomas accurately before treatment, and the quantitive index K^trans is the parameter with the highest sensitivity and specificity.