| ObjectiveTo investigate the clinical value of multivoxel proton magnetic resonance spectroscopy(~1H-MRS) and diffusion weighted imaging(DWI) of 3.0 T MRI in characterization of brain tumors.MethodsThirty-two patients with histological confirmed intracranial tumors (8 cases of low-grade gliomas, 8 cases of high-grade gliomas, 7 cases of single metastases, 9 cases of meningiomas) underwent conventional MRI,~1H-MRS and DWI. 1,~1H-MRS: Regions of interests included solid areas, edema areas and control areas. NAA, Cho, Cr and other metabolite peaks were measured from above regions, and NAA/Cho, NAA/Cr, Cho/Cr ratios were calculated for each voxel. Analysis of the concentration ratios is helpful to present the abnormal findings of brain tumors, and it is useful in the differential diagnosis of brain tumors and in characterization of metabolic changes associated with tumor progression, degree of malignancy, and distinction of neoplastic versus non-neoplastic lesions. 2,DWI: The ADC values were calculated from various areas including solid areas, edema areas and control areas, and the differences of the mean ADCs were analyzed. Analysis of ADC values has the contribution to distinguish the normal white matter areas from tumor component, edema, necrosis and cyst degeneration. DW imaging and ADCs were very effective in the grading the tumors and in the demarcation of tumors owing to the directional dependence of molecular diffusion. 3,Analysis of the characterization of ~1H-MRS and DWI in different areas of various brain tumors. Correlation Analysis between Cho/Cr and ADC values in parenchyma of tumors should be calculated.Results1,MRS:(1)The discrepancy of ~1H-MRS between common intracranial tumors and normal control regions: the peak of NAA and Cr decreased, even disappear, while the peak of Cho increased. The ratios of NAA/Cho and NAA/Cr decreased,while the ratios of Cho/Cr increased. The values differed between tumors and normal control regions(P<0.05).(2)The characterization of metabolites changes of meningiomas: the ratios of NAA/Cr and NAA/Cho in parenchyma of meningiomas were lower than high and low grade gliomas, metastases, while the ratios of Cho/Cr higher than other(sP<0.05); the ratios of NAA/Cr in peritumoral edema of meningiomas were higher than high and low grade gliomas, metastases, while the ratios of Cho/Cr in peritumoral edema lower than high-grade gliomas(P<0.05).(3)The values of metabolites differed between high and low grade gliomas: the ratios of NAA/Cr,NAA/Cho in parenchyma of high-grade gliomas were lower than low-grade gliomas, while the ratios of Cho/Cr higher than the other(P<0.05); the ratios of Cho/Cr in peritumoral edema of high-grade gliomas were higher than low-grade gliomas(P<0.05).(4)The values of metabolites differed between high-grade gliomas and metastases: the ratios of NAA/Cr and NAA/Cho in parenchyma of high-grade gliomas were lower than metastases(P<0.05), the ratios of Cho/Cr in parenchyma of two above tumors presented no significant differences, while the values in peritumoral edema revealed statistically differences between high-grade gliomas and metastases(P<0.05).2,DWI:(1)The distinction of mean ADCs between common intracranial tumors and normal brain: the values of ADC in parenchyma of high and low grade gliomas, metastases were significantly higher than normal control regions(P<0.05); while the ADCs in parenchyma of meningiomas were similar to normal.(2)The values of ADC differed between high and low grade gliomas: the ADCs in parenchyma and peritumoral edema areas of high-grade gliomas were both significantly lower than the other(P<0.05).(3)The values of ADC differed between high-grade gliomas and metastases: the ADCs in parenchyma of two above tumors presented no significant differences, while the values in peritumoral edema areas revealed statistically differences between high-grade gliomas and metastases(P<0.05).3,Correlation Analysis between Cho/Cr and ADC values in parenchyma of tumors:the data were calculated using x-y scatter, the correlation coefficient : r=-0.674(P<0.05)ConclusionMultivoxel ~1H-MRS non-invasively provides information on the biochemical profile of brain tissue, which varies according to the underlying disease process. It has the contribution to calculate spectroscopic ratios in the differentiation (benign vs malignant) and grading (low or high) of tumor types. It helps to definite the boundary of the lesions. In this study, we aimed to evaluate the hypothesis that the combination of MR spectroscopy and ADC calculation could improve the preoperative diagnostic effectiveness of MR imaging in patients with brain tumors, within an acceptable additional acquisition time. |
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