| Objective:To evaluate the character of metabolites in gliomastumors,peritumoral areas and contralateral normal areas in vivo by 2Dproton MR spectroscopy and to report its significance to gliomas indiagnosis,differential diagnosis,pathological grade,managementplanning and differentiation of delayed cerebral necrosis andrecurrence of cerebral gliomas after radiotherapy.Methods:30 pathologically confirmed cerebral gliomas underwent MRimaging,contrast-enhanced MR imaging and MR spectroscopy by SiemensSymphony 1.5T(11 cases underwent operation or radiotherapy beforethis study).2D1H-MRS used PRESS sequence which was used with TR/TE =1500/270ms, slice 5mm,multivoxel phase-encoding steps,and 23×23cmFOV to scan tumors,peritumoral areas and contralateral areas.It shouldbe careful to avoid the cystoid part of the tumors or/and normal braintissue and normal fat tissue while scanning.3D Shim Fieldmap,watersuppression,receiving signal were automatic completed and then phasecorrection ,baseline correction.The peaks of NAA,Cho,Cr, Lip,and Lacin tumors,peritumoral areas,contralateral normal areas were measuredwith FuncTool analysis package.The peak ratios of the metabolites werecalculated by SPSS12.0 statistic package and compared with each other.The peak ratios of NAA/C ,Cho/Cr ,NAA/Cho ,NAA/(Cho+ Cr),Lac/Cr, Lip/Cr,Lac/NAA and Lip/NAA were indicated by average and standard deviation.The diameter of tumors all exceeded 1.5cm.All the patients were dividedinto three groups:benign (grade1,2),transitive (grade 3),malignant(grade 4) by the WHO 2000 grade standard. Result:There were 12 cases of benign tumors,10 cases of transitivetumors and 8 cases of malignant tumors in 30 cases of gliomas.Amongthese cases ,there were 5 cases of delayed cerebral necrosis and 6 casesof recurrence of cerebral gliomas after radiotherapy.The mean peakratios of NAA/Cho,NAA/Cr,,NAA/(Cho+Cr) in malignant tumors were 0.36±0.23,0.98 ±0.21,0.29±0.11,respectively,which were significantlower(p <0.05) than those in the contralateral normal areas. The resultof Cho/Cr and Lac/Cr in the mass were 2.85±1.35,0.37±0.36 repectively.It increased than that of contralateral areas.With the considerationof multivoxel MR spectroscopy,the results showed that increased Cho,decreased NAA and presence of Lac peaks were the main spectroscopicmanifestations of malignant gliomas.Significant increase of Cho in theperitumoral area was also detected.The mean peak ratios of NAA/Cho,NAA/Cr,NAA/(Cho+Cr)in transitive tumors were 0.75±0.13,1.31±0.23,0.46±0.41,respectively,which were significan lower(p<0.05)than tho-se in the contralateral normal areas.A significant difference exis-ted between the NAA/Cr ratios for gliomas of benign group and forgliomas of malignant group(p<0.05).A significant difference also exist-ed between the Cho/Cr ratios and NAA/Cho ratios for gliomas of benigngroups,and transitive,malignant group(p<0.05),but no significant dif-ference between transitive and malignant group.There is no significant difference between the Lac/Cr ratios for gliomas of three groups.And there was no reliable correlation between the lactate signal andthe grades of gliomas.We observed decreased or disappeared Cho,NAA,Crand appeared Lipid in three cerebral necrosis and disappeared Cho,NAAand Cr with a flat curve without Lac in two cerebral necrosis. Among6 cases with recurrence of cerebral gliomas after radiotherapy ,6 casesexhibited increased obviously Cho ,decreased or disappeared NAA,Cr andincreased Cho/Cr and decreased NAA/Cr, 2 cases showed abnormal lactate,no lipid. Conclusion:①The major proton spectroscopic features of gliomasare increased Cho ,decreased NAA or/and presence of Lac peaks.②Decre-ased or disappeared NAA,Cho,Cr and presence of Lipid peaks are themajor proton spectroscopic features of delayed cerebral gliomas necro–sis after radiotherapy.③The major proton spectroscopic featuresof recurrence of cerebral gliomas after radiotherapy are increasedobviously Cho,decreased or disappeared NAA,Cr.④Proton MR spectro-scopy provides a helpful technique of quantitative analysis for grad-ing of gliomas on MR images.⑤2D1H-MRS is capable of detecting meta-bolic abnormalities outside the tumor.It may be helpful in differ-ential diagnosis,stereotactic biopsy and management planning of cere-bral gliomas. |
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