MR Spectroscopy Of Human Astrocytoma And The Correlation With The Expression Of Ki-67 And Bcl-2

Background and Objective:Astrocytoma is a common intracranial neoplasms derived from the neural epithelium and mainly composed of neoplastic astrocytes. Definitions of tumor hierarchy and the degree of malignancy carry the significant values in determining treatment programs. In the past, the diagnosis of astrocytoma was based primarily on plain and enhanced MRI examinations,which,however, had the limitations in the grading of malignant astrocytoma. MR spectroscopy (MR spectroscopy, MRS) is not only used to analyze a series of specific nucleus and its compounds by MR phenomenon and the role of chemical shift,but also is the only non-injury approach of studying human organs, tissue metabolism, biochemical changes and quantitative analysis of compounds, acquiring biochemical metabolism information of living tissue.With respect to complicated histologic, pathological grade and obvious disparity in immunophenotypic features,their prognoses are quite different and difficult to evaluate. Recent studies suggest that some gene changes,material expression, glioma proliferation and pathological grade are closely related with patient prognosis. Ki-67 proliferation antigen is the most known representative of proliferation index. bcl-2 is a more in-depth study of apoptosis suppressor gene.To make clear the influencing factors of astrocytoma prognosis, guide clinical treatment, purposes of this paper are as follows:1.to study the finding of astrocytoma proton magnetic resonance spectroscopy (proton magnetic resonance spectroscopy'H-MRS), its clinical significance and the 'H-MRS features associated with pathological levels; 2.to investigate the relationship between the Ki-67,Bcl-2 expressions of human astrocytoma. and its pathological classification；3.to approach the correlation between magnetic resonance spectroscopy of astrocytic tumors and the expressions of tumor cells bcl-2 protein, proliferating cell nuclear antigen (Ki-67).Materials and Methods:1. Materials:Collected from January 2006 to December 2009 by the General Hospital of Shenyang Military Region,52 cases of astrocytoma including 28 males and 24 females were confirmed by clinical surgery and pathology,Their ages were from 10to77 years, and the average was 38 years,. All patients underwent conventional MR and 1H-MRS examinations. All specimens were fixed by formalin, embedded by paraffin,and the typical lesions of paraffin blocks were serially cut.2. Method:2.1 MR equipment and imagingMagnetic resonance imaging was conducted by GE Signa MR/iTMl.5T Hispeed Plus superconducting magnetic resonance scanner. Standard head coil for transmitting and receiving coils. all patients were Supine position and underwent conventional T1-weighted imaging, T2-weighted images, enhanced scanning and multi-voxel spectroscopy scan. Intravenous bolus injection dose of GD-DTPA is 0.2mmol/kg weight by conventional contrast enhanced T2WI. before enhancing, the tumor area and the contralateral normal brain tissue area were measured by multi-voxel spectroscopy scanning and point-resolved spectroscopy (PRESS) sequence. Metabolite changes were detected in different regions.2.2 ImmunohistochemistryThe expressions of Ki-67 and bcl-2 protein in normal brain tissue astrocytoma were detected by applications of tissue microarray and immunohistochemical staining. The maximum of NAA/Cho, Cho/cr and the minimum of NAA/cr were recorded and the relationship with tumor grade was analyzed. The relationships between the above indices and ki-67, bcl-2 were investigated respectively.By streptavidin protein monoxide enzyme-linked method (Streptavidin/Peroxidase, SP), an antibody is mouse anti-human bcl-2 monoclonal antibody (to-use type); the other is mouse anti-human Ki-67 monoclonal antibody (to-use type) and both were purchased from Beijing Zhongshan Biotechnology Co., Ltd.. Paraffin sections of conventional de waxing, hydration, select the typical lesions of paraffin blocks of serial sections. Followed by immunohistochemistry kit for detection,the steps according to a prospectus.3. The results determineThe bcl-2 positive cells appeared brown-yellow granules in cytoplasm and Ki-67 positive cells appeared it in nucleus as a standard. According to the percentage of positive cells and staining intensity,these cells were divided into three:the number of positive cells≥25%, with light brown for the (+); positive cells>75%, with dark brown positive cells for the (+++); and color intensity in between for the (++);Results:1. The findings of MRI and'H-MRS:MRI findings were as followings:the signal intensity was mostly heterogeneous on T1WI,T2WI,the apparent and partial intensified.Cr slightly decreased, and NAA distinctly decreased, but Cho obviously increased in astrocytoma. The ratio of NAA/Cho,NAA/Cr decreased,howerer, Cho/Cr increased. The ratio of Cho/cr in the high grade astroaytoma was higher, while NAA/cr and NAA/Cho was lower than that of low grade astrocytoma and control group. There was significant correlation between the ratios of NAA/Cr, Cho/cr and NAA/Cho and the pathological grading of astrocytoma,there was significantly negative correlation in the ratios of NAA/Cr and NAA/Cho (rs was-0.632,-0.798 respectively),and positive correlation in the ratios of Cho/Cr(rs was 0.816).2. Immunohistochemistry results:The protein expressions of ki-67 and bcl-2 in astrocytoma was related with malignancy of astrocytoma. Positve expression of ki-67,bcl-2 increased with increasing clinicopathologic grades (r=0.600, p<0.01). Ki-67 and bcl-2 in the low-level and high-level group were significantly different (P<0.05); The expressions of Ki-67 and bcl-2 was closely related (P<0.05).The ratio of Cho/cr was strongly positively correlated with expressions of bcl-2 and ki-67(r=0.745, p<0.01; r=0.818, pp<0.01 respectively).The ratio of NAA/Cho was weakly positively correlated with expressions of bcl-2 and ki-67(r=-0.253, p<0.01; r=-0.501, p<0.01 respectively). The NAA/cr of astrocytoma was weakly related with expressions of bcl-2 (r=-0.374, p<0.01) and ki-67 (r=-0.436, p<0.01).Conclusion1. The degree of expressions of Ki-67 in low grade and high grade astrocytoma was distinct and increased with the level.2. The degree of expressions of bcl-2 in low grade and high grade astrocytoma was different and raised with the hierarchy3. bcl-2 and Ki-67 played significant roles in the occurrence and development of cerebral astrocytoma,, and the two joint detections can be used to judge the degree of malignant astrocytoma indicators.4.'H-MRS has made it possible to evaluate the grade of astrocytoma. MRS can reflect the protein expressions of Ki-67 and bcl-2 in astrocytoma in principle, predict metabolism, the potential growth, invasiveness of astrocytoma and also can forecast prognosis of astrocytomas before surgery. The ratios of Cho/cr, NAA/Cho reflected pathologic grade of astrocytoma more steadily and were more valuable than NAA/cr.