The Application Of ~1H-MRS In The Diagnose Of Common Intracranial Tumors

The types of intracranial tumors is a great variety, and the classification of them is very complex. And there have a world of differents in the aspect of cure method and prognosis by the different type and different level neoplasm. The routine examination of CT and MRI can merely put out the preliminary diagnosis to aim directly at location, morphous and size of tumors, but can hardly determine the nature of them. MRS as the only noninvasive examination can observe the change of the cellular metabolism continuous, and carry out the qualitative analysis with the metabolism, biochemistry and chemical compound ingredients of the tumors. Accordingly, MRS could provide more quantity and more precise information of neoplasm, could provide liable theory in laying treatment perscription and evaluating therapeutic efficacy.The change of routine MRI and MRS which has taken by the 99 cases of intracranial tumors of different types were analyzed retrospectively. The purpose of this investigation is to evaluate the diagnostic and differential diagnosis value of MRS in the intracranial tumors. The results can provide evidence to diagnose more accuratly, confirm level and boundary of tumors, understand the characteristics of neoplasm, it also play a key role in the prognose of clinical process.Methods: All case were performed by SIEMENS 1.5T Avanto MR system, use the phased-array coil to complete MR scanning. At first, routine MR: transverse section scan included T1WI,T2WI,FLAIR, sagittal T1WI and coronal T1WI scan. Scan series and parameters: transverse, sagittal and coronal T1WI scan use SE series: TR/TE=400/7.8ms; transverse T2WI scan use TSE series: TR/TE=3250/99ms; transverse FLAIR series: TR/TE=9000/109ms, TI=2500ms. the slice thickness was 6mm, the slice interval was 0.6mm, the matrix was 256×256, FOV: 230mm×230mm. MR enhancement scanning: GD-DTPA was injected through vein, dosage: 0.1mmol/kg, and then take the transverse, sagittal and coronal T1WI scaning. ~1H proton Magnetic reconance spectroscopy used chemical shift imaging (CSI) methord: TR/TE=1500/135ms, FOV:160mm×160mm , VOI: 80mm×80mm, stimulated time: 4, acquisition time: 7min12s. Compared the ratio of NAA/Cho, NAA/Cr, Cho/Cr with region of tumors, perienhancement and normal regions.Results: Routine MR plain scan in T1WI intracranial tumors usually manifest equal or lower signal, and uniform or nonuniform higher signal in T2WI, nonhydropsia or different level hydropsia surrounding tumors. Enhancement scanning: neoplasm can manifest non-enhancement, uniform or nonuniform enhancement, so there has some difficulty in the classfication of intracranial tumors, can hardly make qualitative diagnose preoperation. The tumors'~1H–MRS is obviously different with normal brain tissue. The ratio of NAA/Cr,NAA/Cho cut down, the ratio of Cho/Cr step up. The NAA/Cr ratio in the region of glioma enhancement is obviously different with meningioma and metastasis(P<0.05). Analysis perienhancement feature of MRS in further step, we have discovered the metabolism ratio in perienhancement of glioma is obviously different with normal tissue(P<0.05). But meningioma and metastasis do not have the feature(P>0.05). The diversity of NAA/Cho ratio in the perienhancement of 3 different tumors has statistics sense(P<0.05). At last, compared the metabolism ratio with tumors and perienhancement of different types of tumors, the ratio of NAA/Cho in meningioma have obviously cut down to the perienhancement, and Cho/Cr ratio step up(P<0.05).Conclusion:1,Routine MR plain scan in T1WI intracranial tumors usually manifest equal or lower signal, and nonuniform higher signal in T2WI, accompainied with different level hydropsia surrounding tumors and enhancement, so there has some difficulty in the classfication of intracranial tumors.2,The tumors'~1H–MRS is obviously different with normal brain tissue. The ratio of NAA/Cr, NAA/Cho cut down, the ratio of Cho/Cr step up.3,~1H–MRS could classified different type of intracranial tumors in molecular level, so it can retrieve the defect of routine MR in clinic.4,~1H–MRS could provide quantitative and semiquantitative method to assay the grade of malignacy, supply consult information for pathology classify, for overall and accurate evaluation with tumors pre-operated, for formulating reasonable treatment perscription.5,The evaulation of perienhancement by mult-voxel ~1H–MRS is very valuable for the classification of glioma meningioma and metastasis and the designation of tumors'infiltrating extent.