| Objective To investigate 1H MR Spectroscopic profile of the common intracranial tumors and analyze changes in signal intensities of chemical resonance of major metabolites; To evaluate clinical applications of 1H MRS combining with MRI.Materials and Methods 107 cases with intracranial lesions examined by MRI were performed with 1H MRS. At the same time spectrums were obtained from contralateral normal-appearing brain parenchyma in 15 cases with brain tumors and 20 volunteers, which were granted as controlled group.All the cases were grouped according to pathology and following-up. The group one: intracranial tumor group(75cases) and controlled group(35 case); The group two: intracranial tumor and non-tumor (30 cases); The group three: neuroepithelial tumor(34 cases)and meningioma ; The group four : neuroepithelial tumor(34cases) and metastasis tumor(10cases). The group five: benign gliomas (grade I— Ⅱ astrocytoma ,12 cases) and malignant gliomas(grade Ⅲ -Ⅳ astrocytoma, 16cases).All the patients were examined on a 1.5T MR scanner (Magnetom Sonata Maestro Class, Siemens company). Single-voxel 1H MRS was performed using point resolved spectroscopy (PRESS) technique. Data post-process and display were done with SPECTROSCOPY post-process software package in LEONARDO work stage. Six major metabolites were observed: NAA, Cr, Cr2, Cho, Lac and Lip. Take the area under the curve as the relative density of the metabolites, and calculate the ratio of Cho/Cr , NAA/Cr , Cho/NAA. Finally the statistical value of all metabolite concentrations and their ratio was compared in different groups.Results1.The first group: compared with normal cerebral parenchyma , the NAA of all the intracranial tumors decreased or disappear. The Cho and ratios of Cho/Cr, Cho/NAA increased while the ratio of NAA/Cr decreased. Glx appeared in 93.8% ( 15/16) of all the meningiomas and Ala peak in 25% (4/16) was detected. Neverthless,neither of them was seen in other tumors. The specificity, sensitivity and accuracy were respectively 100%, 93.8%, 99%. NAA peak disappeared in the 83.3%(32/39) of non- neuroepithelial tumors(such as meningiomas, metastases, pituitary tumors , chordomas and cavernous hemangioma)which specificity and sensitivity is 94.4%, 82.1%. All the resonance signal peak vanished in 1 cavernous hemangioma, 1 chordoma and 1 osteoblastoma, but only Lip peak was detected.2.The second group: the group of tumor had higher Cho, the ratio of Cho/ Cr and Cho/NAA ( P<0.05 )and lower NAA( p<0.05 )than the group of non-tumor.3.The third group: glioma had higher NAA and lower Cho comparedwith meningioma (P<0.05) .4.The fourth group: the NAA concentrate of nueroepithelial tumors were higher than metastatic tumors. There was no statistic significance in the contents of other metabolites and the ratio of them between gliomas and metastases (P>0.05) .5. The fifth group: benign gliomas had higher NAA/Cr ratio, lower Cho, ratio of the Cho/Cr and Cho/NAA than malignant gliomas.Conclusions1.The 1H MRS manifestation of different intracranial tumors is relatively specific. 1H MRS can increase the diagnosis accuracy of the tumor that we cann t diagnose correctly. NAA resonance signal of all the intracranial tumors decreases or is absent. The Cho and the ratio of Cho/Cr and Cho/NAA increase in all the tumors especially in meningioma. The NAA peak decreases in gliomas, while disappears in non-neuroepithelial tumor, such as meningiomas and metastases, which is their character. Glx and Ala peaks specifically appear in meningiomas. NAA and Cr peaks disappear in metastatic tumor and appears single Cho peak or appears Lip and Lac peaks.2.There is different 1H MRS manifestation in intracranial tumors and non-tumor group. While intracranial tumor has lower NAA, higher Cho and the ratios of Cho/Cr and Cho/NAA.3.Compared with neuroepithelial tumor , meningioma has no NAA peak, while nuroepithelial tumor has NAA peak , but his density is lower; Both of their Cho and Cho/Cr increased, especially in meningioma which increased much more dramatically.4.Comparing nueroepithelial with metastatic tumors, NAA peak of the former decreases, while disappears in the latter.5. The Cho and the ratio of NAA/Cr, Cho/Cr and Cho/NAA of benign glioma are higher than malignant glioma. There is no statisticdifference in NAA, Cr and Cr2 between this two groups.6.As a non-invasive method to investigate substances and energy metabolization of the intracranial tumor !H MRS can supply biochemial information of metabolites of tissue, which is helpful to diagnosis and differential diagnosis of various intracranial tumors. It also can supply important information about grading and type of the tumors, and evaluation of recurrence post-operation, therapy effective and Stereotactic biopsy.7.1H MRS can't replace of conventional MRI in diagnosis and differential diagnosis of the intracranial tumors, which must be combined with the findings in conventional MRI.
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