The Clinical And Experimental Study Of MR Perfusion Weighted Imaging In Cerebral Gliomas

Gliomas are most common primary neoplasms of the brain. They have a heterogeneous histologic spectrum, and at biopsy their grade thus tends to be underestimated. In spite of improvements in the results of surgery, radiation therapy and chemotherapy, the prognosis of patients with gliomas, particularly those with high-grade tumors, remains poor. For planning the optimal treatment strategy and assessing prognosis, accurate histologic grading is essential, and for this, vascular proliferation is an important criteria; in determining the histologic grade of a glioma, the evaluation of tumor vascularity is therefore valuable. Recent developments in MR perfusion weighted imaging (MR PWI) techniques can assess distribution of microvessel and blood perfusion of tissue,and provide hemodynamics information. So MR PWI have permitted the creation of cerebral blood volume (CBV) maps, leading to thequalitative and quantitative assessment of tumor vascularity. These maps have helped in the assessment of tumor grade and in targeting the site of biopsy. The purpose of this study was to evaluate the role of MR PWI in pre-operation grading of gliomas and investigate the feasibility of rat C6 brain glioma model in MR PWI research.Objective:1 To evaluate the value of MR PWI in preoperative grading of cerebral gliomas.2 To investigate the expression of NF- k B protein and the relationship between the expression of NF- k B and angiogenesis in cerebral gliomas.3 To investigate the correlation of rCBV with vascular endothelialgrowth factor ( VEGF ) protein expression and microvessel density (MVD) in cerebral gliomas.4 To study the value of conventional MR in long-term follow-up andthe feasibility in MR PWI research of rat C6 brain glioma model.Methods:1 MR examinations were performed preoperatively in 30 patients with suspected supratentorial gliomas. All the 30 cases were proved by operation and pathology. The procedures of MR examinations included plain MR scan, PWI and routine contrast-enhanced MR scan. The pulse sequence of PWI was GE-EPI. The CBV and CBF maps were calculated from the original data of perfusion images and the maximum rCBV and maximum rCBF of gliomas were acquired from CBV and CBF maps through measurement on the region of interest (ROI). Theresults of maximum rCBV and rCBF were correlated with those of histopathologic gradings. The correlation between rCBV and rCBF was evaluated using spearman's rank correlation analysis.2 The expression of NF- k B p65 protein, VEGF protein and MVD in 30 cases of cerebral gliomas and 10 cases of normal brain tissue were detected inimunohistochemically.The correlation of NF- k B, VEGF and MVD was studied.3 According to the situation of VEGF protein expression, all the 30 cases were divided into two groups including positive VEGF protein expression group [VEGF( + )] and negative VEGF protein expression group [VEGF(-)]. Wilcoxon test was used for comparing the difference between the two groups. Linear correlation analysis was used for observing the correlation between rCBV and MVD in gliomas.4 By using the sterotatic method to implant C6 cells into the right caudate nucleus of rat, to set up the rat C6 brain gliomas model.The cell density of inoculation is 1x106 /10ul. On the following days, common condition and MR features of the rats were observed. MR PWI were performed in the dying rats. The specimens of tumors for pathological study were collected in the dying time or after the death of rats immediately.Results:1 The rCBV and rCBF in grade I-II gliomas were 0.72-4.26 and 0.82-2.89 respectively, with a mean of 2.10+0.88 and 1.52+0.65. The rCBV and rCBF in grade III-IV gliomas varied from 0.89-10.02 and 1.50-6.04 with a mean 5.23+1.89 and 4.81+1.60. The difference in rCBV and rCBF was statistically significantbetween grade I-II and III-IV gliomas (student t test, p<0.01). There was a strong correlation between rCBV a...