Clinical Application Of 2D～1H-MRS In Evaluation Of Intracranial Gliomas

BackgroundGliomas are the most common primary neoplasms of the central nervous system with refractory and recurrent characteristics, an high disablement and lethality rate, Magnetic resonance imaging (MRI) is the well-established non-invasive tool of choice for evaluation of brain tumors because of its excellent tissue contrast and the availability of multi-planar and multi-parameter imaging, Moreover, the use of Gd-DTPA improves the depiction and detection of brain tumors, However, conventional post contrast MR images do not provide information about tumorous proliferation, neuron damage, tumor microvessel vascularity, hypoxia and micro-necrosis, which have close relation to tumors' invasiveness and patients' prognosis, It has great clinical significance to make a clear detection about tumor proliferation, neron damage, tumor vascularity, hypoxia and micro-necrosis, for choosing the apropos treatment plan and making an apt evaluation of prognosis.Functional magnetic resonance imaging(fMRI) have been used to evaluate the situation of metabolism and vascularity of glioma. Magnetic resonance spectroscopy(MRS) is the only feasible imaging way for non-invasively evaluating the metabolites in vivo, ~1H-MRS has broad clinical application prospects in diagnosing, differential diagnosing and grading of gliomas, In the past few years, some reports on intracranial gliomas either ~1H-MRS were often presented.With the rapid development of molecular biology, glioma was thought to be a disease involving multiple gene mutations. The synthesis and expression of proliferating cell nuclear antigens (PCNA) might be related to the state of proliferation of the neoplastic cells. PurposeAssessment of brain tumor proliferative potential provides important prognostic information that supplements standard histopathologic grading. Proton magnetic resonance spectroseopy(1H-MRS) gives completely different information, relating to cell membrane proliferation, neuronal damage, energy metabolism and necrotic transformation of brain or tumor tissues. The aim of this study was to investigate the relationship between 1~H-MRS and tumor proliferative potential in astrocytomas.Methods1. 58 patients with surgically and pathologically proved astrocytoma were analyzed. They were performed MR, MRS, and MR enhancement scan before operation. Fast spin echo(FSE) and spin echo(SE) pulse sequences were used for conventional MRI. Point-resolved spectroscopy(PRESS) was used for 2d~1ll-MRS.2. All the imaging data were transmitted to Sun spare ADW4.0 workstation for post-treatment and analysis. Functool 2000 software package was used for mapping of main metabites such as N-aeetyl aspartate(NAA), choline(Cho), creatine(cr), lipid(lip) and lactate(Lac), The ratio of metabolic material (Cho/Cr, ,NAA/Cho) came from different areas of tumors were calculated respectively.3. According to the result of the MRI and 1~H-MRS, we calculate the degree of malignancy of brain tumors preoperative.4. The result of surgically and pathologically were Contrasting analyze with the preoperative consequence, researching the correlation of the ratio of metabolic material, the degree of malignancy of brain tumors, and proliferating cell nuclear antigens.5. Drawing the correlation curve of the degree of malignancy of brain tumors with the ratio of metabolic material came from different areas of tumors and cell proliferation.ResultAll the patients tolerated conventional MRI and 2D~1H-MRS without producing motion artifacts, According to the diagnosis of postoperational pathology, they were divided into three groups, that is, astrocytoma (AS,n=21), anaplastic gliomas(AG,n=24) and glioblastoma multiforme(GM,n=13), The relative concentrations of NAA, Cho, Cr, Lip-Lac, and ratios of Cho/Cr and NAA/Cho see Tablel.The ratios of metabolic material (Cho/Cr, Cho/NAA) of astrocytoma proved high pathological grade were significantly higher those of astrocytoma proved lower pathological grade(p＜0.01). There was existed in the correlation between PCNA expression of different grade astrocytoma and the ratio of Cho/Cr(p＜0.01).The Cho/Cr ratios were significantly correlated with the expression of PCNA (r=0.959, p＜0.01).Conclusion1. For NAA, the higher the grade was, the lower the content, NAA can be the index of destruction of normal neuron and its axis. Cr had no obvious changes or slightly lowered in gliomas.2. For Cho and Cho/Cr, the higher the grade was, the higher their contents were, But Cho/Cr was more sensitive than Cho. For NAA/Cho ratio, the higher the grade was, the lower the ratio. NAA/Cho ratio can be looked as a synthesized index for evaluation of normal neuron destruction and tumor cell, proliferation.3. Lip-Lac content increased in gliomas, especially in high-grade ones.4. In our studay, the Cho/Cr ratios correlated significantly with PCNA integral light density, implying that the Cho/Cr ratios might predict the degree of the gliaI cell proliferation in astrocytomas. Conversely, in the light of cell proliferation, the Cho/Cr ratios in astrocytomas have the potential to predict the degree of malignancy of brain tumors.