The Correlative Study Of VEGF Expression Levels And Dynamic Contrast-enhanced T₁-weighted Imaging Together With Conventional MRI Feature In Astrocytoma

Objective: Vascular endothelial growth factor (VEGF) contributes to the progression of human astrocytoma by playing an important and pivotal role in inducing angiogenesis. We planed to investigate the correlation between VEGF expression levels and dynamic contrast-enhanced T1-weighted TurboFLASH imaging together with conventional MRI feature in astrocytoma.Methods: We examined 33 patients with histologically verified astrocytoma. Astrocytomas were classified grade â…  , â…¡ , â…¢ , â…£. Gadolinium-enhanced dynamic Turbo-FLASH imaging was performed preoperatively in all patients followed by conventional MRI. The steepest slope (SSmax) of curve and corresponding Tm1 in "first-pass" phase can be obtained by analyzing time-signal curve. The expression levels of VEGF were obtained (-, + , ++,+++) after all specimens were immunostained with anti-human VEGF monoclonal antibody postoperatively by streptavidin-peroxidase method. The same immunohistochemical technique was also used to detect microvascular density (MVD) with anti-human Factor â…§ related antigen monoclonalantibody. The correlation tests were used to determine the strength of the relationship between SSmax ,Tm1 and VEGF expression levels. Conventional MRI features (peritumoral edema , cystic degeneration and necrosis, the degree, shape of contrast enhancement ) of all specimens were compared with VEGF expression levels.Results: Significant difference (P<0.05) in SSmax , Tm1 was found among astrocytomas according to different VEGF expression levels. SSmax correlated well with VEGF expression levels (Ys =0.6810, P<0.001). Negative correlation existed between Tml and VEGF expression levels (ys=-0.6970, P<0.001). Peritumoral edema , cystic degeneration and necrosis, the degree of contrast enhancement became serious with VEGF expression upgrading, and the shape of contrast enhancement became irregular. There was significant difference (P<0.05) of MVD among astrocytomas according to different VEGF expression levels. There was significant difference (P<0.01) of VEGF expression in astrocytoma of all grades.Conclusion: VEGF expression levels correlated well with SSmax and Tml in astrocytoma, and the pathophysiological base is that VEGF plays pivotal role in inducing angiogenesis. VEGF expression in astrocytoma had obvious influences on peritumoral edema, cystic degeneration and necrosis, the degree and shape of contrast enhancement. TurboFLASH sequence with high time resolution and high T1 susceptiveness can beapplied to dynamic contrast-enhanced MRI. Combining dynamic contrast-enhanced MRI with conventional MRI features in astrocytoma can help to estimate VEGF expression and MVD.