The Application Study Of Proton MR Spectroscopy On Intracranial Tumors

【Objective】1.To investigate the metabolic changes of 2D- multi-voxel proton magnetic resonance spectroscopy(2D-multi-voxel ~1H MRS) in enhancement areas of different brain tumors and to evaluate its role in differential diagnosis of brain tumors.2.To investigate the metabolic changes of 2D-multi-voxel ~1H MRS in edema areas of different brain tumors and to evaluate its role in differential diagnosis of brain tumors.3.To investigate the metabolic changes of 2D-multi-voxel ~1HMRS between high -grade and low-grade gliomas and to evaluate its role in preoperative judegment the grade of gliomas.【Methods】1.Investigation objects61 cases of brain tumor patients underwent MR imaging,contrast-enhanced MR imaging and 2D-~1HMR spectroscopy imaging.In addition to some of Intracranial metastases tumors confirmed by clinical,all the remaining cases were Confirmed by postoperative pathology.In 61 cases,26 cases was glioma,in which 14 cases was low-grade(Ⅰ-Ⅱ) glioma,12 cases was high-grade(Ⅲ-Ⅳ) gliomas,andl7 cases was meningiomas,18 cases was metastatic tumor. 2.MRI scanning methodsAll scanning adopt GE signa exciteⅡ3.0T MRI scanning equipment. Conventional MRI scan used eight Channel coil Dedicated for head.getting T1WI, T2WI image by SE and FSE Sequence and getting Enhanced image in T1WI after Gd-DTPA injection,Scan Parameters:T1WI(TR/TE,600/16ms),T2WI(TR/TE, 5100/138ms),Thickness 5-8mm,Pitch 2mm,FOV 24×18mm,matrix 512×288. ~1HMRS scanning used eight Channel Coil Dedicated for head.Adopted 2-D multi-voxel(PROBE/SI) PRESS sequence,and set TR /TE:1000ms/144ms. Frequency Coding set of 16,Direction is A/P,voxel thickness lOmm,Pitch 20mm, NEX 1,FOV18×18m.Scan positioning some in Enhanced-T1WI image of complete Axial and another in T2WI image of complete Axial,The MRS scan VOI Should Including tumor areas,peri-tumor edema areas and a part of normal areas away from tumor areas,but should try to avoid skull,fat,liquid Organization and so on.The MRS scan started after FWHM＜lOppm,chress＞98%.3.Image postprocessing and survey dataOn the" FuncTool' Workstations,All of cases setting three regions of interest (ROI),which are located respectively in enhanced tumor regions,edema regions near the enhanced areas for 1-2cm and normal regions away from tumor,in the "AI+MI" Images.Observed the changes of the metabolism in the corresponding spectrum images(SI),measured the relative ratio of Cho / Cr,NAA / C,Cho / NAA,and Recorded Lip and Lac whether appeare in Every cases.4.Statistical analysisSPSS 13.0 statistical package was used.The measurement data were represented as mean±standard.(1).comparing each relative ratio of metabolites of normal areas in the three tumor groups;(2).Comparing each relative ratio of metabolites between the enhanced areas and normal areas in each groups,and comparing each relative ratio of metabolites of enhanced areas in three tumor groups;(3).comparing each relative ratio of metabolites of edema regions in the three tumor groups;(4).Comparing each relative ratio of metabolites Respectively in enhanced region,edema regions between the high-grade gliomas and low-grade gliomas.one-way ANOVA was used in Comparison in different tumor groups,paired-samples T-test was used in Comparison between two regions in same tumor group,one sample T-test was used in Comparison between high-grade and low-grade gliomas.Testing standards "α" adopted 0.05.【Results】1.MRS appearance in normal areasSpectrum image showed There were similar metabolites situation in normal regions among three groups,appearing highest NAA peak,lower Cr and Cho peak. Cho/Cr,NAA/C,Cho/NAA all showed no significance among three groups.No Lac or Lip peak appeared in normal areas.2.MRS appearance in enhanced tumor areasSpectrum image showed roughly similar metabolites situation in enhanced regions among three groups,appearing highest Cho peak,lower Cr and NAA peak Varying degrees,particular,Lower NAA appeared in meningiomas group. Comparison between enhanced and normal regions,showed higher Cho/Cr,Cho/ NAA and lower NAA/Cr in enhanced regions in each tumor groups,there was statistically significant difference between meningiomas and each of other tumor groups for NAA / Cr,Cho / NAA,appearing there were higher Cho / NAA and lower NAA/Cr in meningiomas group.There was no significant between glioma and metastatic tumor for all The relative ratio of Metabolites,There was no significant among Threee groups for Cho/Cr.Lac appeared in 3 cases of meningiomas,6 cases of gliomas and 4 cases of metastatic tumor,lip not appeared in no case of meningiomas group,4 cases of gliomas and 8 cases of metastatic tumor.3.MRS appearance in edema areasSpectrum image showed The metabolites situation in edema regions is different from glioma group to each of other groups,appearing higher Cho peak, lower NAA and Cr peak in glioma group,the similar metabolites situation between meningiomas and metastatic tumor groups,appearing higher NAA peak,lower Cho and Cr peak.on all metabolites ratio,there was statistically significant differences between glioma groups and each of other groups,appeared higher Cho / Cr and Cho / NAA,lower NAA/ Cr in glioma group.There was no significant between meningiomas and metastatic tumor groups for Cho / Cr,Cho / NAA and NAA/Cr.4.different MRS appearance between high-grade and lowe-grade glioma(1).different MRS appearance in enhanced regionsThe Spectrum image showed in enhanced regions there were Increase Cho Peak both in high-grade and lowe-grade glioma groups,but higher in high-grade glioma groups than low-grade group,there were Reduced NAA Peak both in high-grade and lowe-grade glioma groups,but lower in high-grade glioma groups than low-grade group,Cr peak change little.There was significance in enhanced regions between high-grade glioma groups and low-grade group for Cho/Cr,Cho / NAA,NAA/Cr, showed higher Cho/Cr,Cho / NAA and lower NAA/Cr in high-grade glioma group. Lac appeared in 4 case of high-grade group,2 cases of lowe-grade group,Lip appeared in 3 cases of high-grade group,1 case of lowe-grade group.(2).different MRS appearance in edema regionsThe Spectrum image showed in edema regions there were higher Cho Peak and lower NAA peak both in high-grade and lowe-grade glioma groups.There was significance in edema regions between high-grade glioma groups and low-grade glioma group for Cho/Cr,showed higher Cho / Cr in high-grade group,but no significance for Cho / NAA,NAA/Cr between high-grade and lowe-grade group in edema regions.【Conclusions】1.2D-~1HMRS Technology can get Spectrum signals from different areas at one scanning,so that it not only get more comprehensive and Full information about the metabolism of tumor and The surrounding region tissues but also save time Greatly. At the same time,2D-~1HMRS Technology can select More appropriate and more exact voxel without inclusion of unwanted structures which may degrade the spectrum quality;2.There were similar metabolites situation in normal regions among three groups, appearing highest NAA peak,lower Cr and Cho peak.no significance for all metabolites ratio among three groups,that is MRS appearance of normal brain.3.Metabolites situation of enhanced areas were all different from normal areas in three groups,all appearing highest Cho peak,lower Cr and NAA peak Varying degrees,particular,Lower NAA appeared in meningiomas group,there was statistically significant difference between meningiomas and each of other tumor groups for NAA / Cr,Cho / NAA,appearing there were higher Cho / NAA and lower NAA / Cr in meningiomas group.The difference basis may lain in meningiomas does not contain neuron,so have lower or hiatus NAA peak therefore,based on all above MRS difference in enhanced areas,we can better distinguish meningiomas from other tumor.There was not significant for all the relative ratio of Metabolites between glioma and metastatic tumor in enhanced tumor areas,that is to say there was difficulty to differential diagnosis between glioma and metastatic tumor depend on MRS appearance in enhanced tumor areas.Lac is less significance to diagnosis from malignant tumor to benign tumor because Lac appeared in all tumor groups but appeared number was less in each groups.lip appeared in both gliomas and metastatic tumor groups,but no one in meningiomas groups,for this reason,it is possible for Lip can help diagnosis from malignant tumor to benign tumor better,but Lip is less significance to diagnosis between glioma and metastatic tumor.4.Spectrum image showed that the metabolites situation in edema regions is different from glioma group to each of other groups,appearing higher Cho peak, lower NAA and Cr peak in glioma group,the similar metabolites situation between meningiomas and metastatic tumor groups,appearing higher NAA peak,lower Cho and Cr peak.There was statistically significant differences between glioma groups and each of other groups,appeared higher Cho / Cr and Cho / NAA,lower NAA/Cr in glioma group,The difference basis may lain in the characteristic of Infiltrate growth in glioma,based on different MRS appearance in edema regions,it is more easy to diagnosis glioma from other intracal tumor.5.Cho Peak is higher in high-grade glioma groups than low-grade group in enhanced regions,NAA Peak lower in high-grade glioma groups than low-grade group in enhanced regions,there was significance in enhanced regions between high-grade glioma groups and low-grade group for Cho/Cr,Cho / NAA,NAA/Cr, showed higher Cho/Cr,Cho / NAA and lower NAA/Cr in high-grade glioma group. There was significance in edema regions between high-grade glioma groups and low-grade glioma group for Cho/Cr,showed higher Cho / Cr in high-grade group. based on different MRS appearance between high -grade and low-grade gliomas,it is better to help Preoperative pathological grade of gliomas.Though,"Lac","Lip" all appeared more in high -grade gliomas than in low-grade gliomas,the value of helping Preoperative pathological grade of gliomas is pend for studying further.6.Here are a lot of Influencing factor for MRS Imaging and analysis,and there existence overlaps in Various tumor spectrum each other.the accuracy of MRS also is not high.Therefore,MRS as a new method can provide us More Metabolism information about tumor and the vicinity organizes,but only as the powerful replenish for MRI,not substitution.