Study Of Intracranial Tumor And Tumor-Like Diseases With ～1H-MRS At 3.0T

ObjectiveTo study intracranial tumor and tumor-like diseases with multi-voxel ~1H-MRS at 3.0 Tesla MR scanner and to analyze if there is significant correlation between the semi-quantitative data of ~1H-MRS and the quantitative data of immunohistochemical tests of the glioma specimens, then to evaluate the efficacy of combination of ~1H-MRS and DWI in differential diagnosis of intracranial tumor and tumor-like diseases, and finally to find if the result of ~1H—MRS could be influenced by contrast agent. Materials and Methods1.Before treatment 2D ~1H-MRS examinations were performed on 41 proved glioma patients with PRESS sequence. NAA, Cho and Cr were the main metabolites that were investigated. And the ratios of Cho/NAA and Cho/Cr were calculated. The positive expression of Ki-67, PCNA, MMP-2 were showed by immunohistochemical test(SP method). Quantitation of positive expression of Ki-67 was expressed by Ki-67 labelling index(Ki-67 LI) and calibrated opacity density(COD) was used to quantify those of PCNA and MMP-2. The statistical method was Linear correlation analysis. 2. Before treatment 2D ~1H-MRS and DWI examinations were performed on 82 proved intracranial tumor and tumor-like diseases patients with PRESS sequence, including41 gliomas, 19 meningiomas, 14 metastases, 6 abscesses and 2 NHLs. 3 metastases had received treatment before.The ratios of main metabolites and ADCs were measured in the solid part of masses, peritumoral edema(if any) and contralateral parenchyma respectively. The ADCs of cystic part of masses were also measured. ANOVA was used as the statistical method.3. 'H-MRS examinations were taken before and after administration of Gd-DTPA on 33 cases. Peak areas of NAA, Cho, Cr and Cho/Cr, Cho/NAA before and after administration of Gd-DTPA were comparedby paired-samples T test. Results1. Cho/NAA, Cho/Cr, Ki-67LI, PCNACOD and MMP-2C0D of malignant glioma were all more than those of benign glioma significantly. There were strong positive correlation between Cho/NAA, Cho/Cr and KA-67LI, PCNACOD and MMP-2C0D respectively.2. Cho/NAA, Cho/Cr, Lip/Cr, MI+Gly /Cr and ADC of solid part of masses showed significant differences between benign and malignant glioma. Cho/Cr, MI+Gly/Cr of solid part of masses and Cho/NAA of peritumoral edema revealed significant differences between malignant glioma and metastasis. The spectrum of meningioma was featured by its stable baseline, prominent high Cho peak at 3.2ppm and characteristic inverted Ala doublet at 1.47ppm. ADC of cystic part of abscess is significantly lower than that of benign, malignant glioma and metatstasis. ADCs of solid part of two NHLs were lower than those of contralateral parenchyma. 3. After contrast agent administration, only the decrease of peak area of Cho had statistical significance. Conclusions1. ' H-MRS examination and quantification of positive expression of Ki-67, PCNA, MMP-2 with immunohistochemical method are both helpful in grading glioma. There was strong positive correlation between Cho/NAA, Cho/Cr and Ki-67LI, PCNACOD and MMP-2C0D respectively. So 'H-MRS examination could take place of pathology examination to some extent. 2.Lip peak is most useful to distinguish benign and malignant glioma. Setting Cho/NAA=2. 0, Cho/Cr=2.0 andADC=l.lxlO"3mm2/s as thresholds, most benign and malignant gliomas could be differentiated. To discriminate malignant glioma and metastasis, maybe the peritumoral edema should be analyzed by 'H-MRS firstly. Because of the typical spectrum, meningioma is usually easy to be differentiated from other masses. Decreased ADC of abscess cyst is characteristic. 3. Administration of contrast agent will not influence the result of'H-MRS.SignificanceOur study shows that ' H-MRS and pathology examination definitely have correlation. To some degree, 'H-MRS has comparable diagnostic efficacy to pathology examination and has the potential to take place of the latter when it is difficult to determine if a biopsy is worthwhile. Frankly, our study is really primitive. More experience should be achieved from future work. And more exquisite and well-designed researches with large samples on profound topics should be performed to gain more persuasive evidence to verify diagnostic efficacy of MRS. Combination of 'H-MRS and DWI could offer more valuable information and complement each other to improve efficacy of differential diagnosis of intracranial tumor and tumor-like diseases. To examine an ill-defined lesion,' H-MRS could be performed after contrast agent administration to put the ROI precisely without the concern of influence of contrast agent on spectrum analysis.