Functional Magnetic Resonance Imaging Of Astrocytic Tumors: A Study Of Tumor Pathological Grading

Partâ… Evaluation of the pathological grade in astrocytic tumors:Application of MR perfusion-weighted imaging (PWI)Objective:Assessment of perfusion-weighted magnetic resonance imaging(perfusion weighted imaging,PWI) for astrocytic tumors preoperative value ofhistological grade.Materials and Methods:110 cases supratentorial astrocytictumors confirmed by surgery and pathology were analyzed,all cases underwentconventional,contrast MRI scan and PWI examination by using Siemens 1.5Tmagnetic resonance imaging system.According to the World Health Organization(WHO) classification of central nervous system tumors and grading criteria:110cases of astrocytic tumors,40 cases of low-grade (gradeⅠ～Ⅱ),70 cases ofhigh-grade (gradeⅢ～Ⅳ),of which 33 cases and 37 cases are gradeâ…¢,â…£.Pseudo color pictures of CBV were obtained by PWI on the post-processingworkstation,ROI placement were proceeded through application of hot spotsanalysis,maximum rCBV values of solid part,surrounding area of tumor,and thecorresponding contralateral normal white matter are caculated.Comparison ofdifferent levels of maximum tumor rCBV values were assessed by using analysis ofvariance;comparison between the two groups using t test;drawing ROC curve todetermine the ideal maximum value of rCBV threshold between high-grade andlow-grade astrocytic tumors.A significance level of 5% was assumed.Results:Themaximum value of rCBV in the solid part of astrocytic tumors are related positivelylinearly with pathological levels,the maximum rCBV values of gradeâ… -â…¡,â…¢,â…£were 1.708±0.535,4.207±0.808 and 6.693±1.220 respectively,significantdifferences were showed among all grades of astrocytic tumors(both P=0.000);Themaximum value of rCBV in the surrounding area of astrocytic tumors are also relatedpositively linearly with pathological levels,the difference between levels with thesame statistical significance (P=0.000).Compared the maximum rCBV values of solid part and surrounding area of astrocytic tumors,the former superior to the later.To the highest rCBV values of solid part of tumor to identify the high-level andlow-grade astrocytic tumors,2.618 as the ideal threshold,the A_Z value obtained underthe ROC curve of 0.993,the sensitivity and specificity were 98.60%,95.00%.Conclusion:PWI examination can obtain CBV map which reflect blood volumechanges in astrocytic tumors,and the blood volume change of solid part of tumor islinear related with the histological grade,so by testing and calculation of themaximum rCBV value,will be able to assess the level of tumor pathology.PWIexamination for preoperative evaluation of astrocytic tumors have a higher value ofhistological grade.Partâ…¡Application of MR diffusion-weighted imaging(DWI)toassess the pathological grade in astrocytic tumors andrelated research between the ADC value and Ki-67 labelingindexObjective:To evaluate diffusion-weighted magnetic resonance imaging (diffusionweighted imaging,DWI) for astrocytic tumors preoperative value of histologicalgrade,and correlation between the minimum ADC value of tumor and Ki-67 labelingindex of.Materials and Methods:The first part of the same.All patients wereunderwent conventional,contrast and DWI MRI scan by Siemens 1.5T magneticresonance imaging system.Post-processing workstation for access to ADC map.ROImethodology were used to detect the amount of solid tumors and tumor-surroundingarea part of the minimum ADC value.Pathological sections were obtained after Ki-67immunohistochemistry to determine the Ki-67 labeling index,analyzed itsrelationship with the minimum ADC value of solid part.Different grades tumors ofminimum ADC value of solid part and surrounding area were assessed by multiple analysis of variance;different levels of tumor Ki-67 labeling index comparsion usingrank sum test;comparison between the two groups using t test;drawing ROC curveto identify the high-level and low-grade astrocytic tumors is part of the minimumADC value of the ideal threshold.The linear correlation analysis between theminimum ADC value of solid part and Ki-67 in astrocytic tumors were assessed byPearson correlation method.A significance level of 5% was assumed.Results:Theminimum value of ADC in solid part of astrocytic tumors and its pathological levelwas negatively correlated,the minimum ADC values of gradeⅠ～Ⅱ,â…¢andâ…£ofastrocytic tumors were 1.40±0.162×10^-3mm²/s,1.067±0.146×10^-3mm²/s and0.854±0.16×10^-3mm²/s,for different levels of solid tumor ADC value was showedstatistically significant difference (P=0.000).The minimum value of ADC in thesurrounding area of astrocytic tumors and its pathological level was also negativelycorrelated,(P=0.000).Analysis showed that part of solid tumors and peri-tumorareas for the assessment of the minimum ADC value of histological grade astrocytictumors showed similar results.To the minimum ADC values of solid part of tumor toidentify the high-level and low-grade astrocytic tumors,the obtained area under theROC curve A_Z value of 0.963,1.196×10^-3mm²/s as an ideal threshold,the sensitivityand the specificity were 90.60%,84.30%.Immunohistochemical analysis,between thepathological grade of tumor Ki-67 labeling index were significantly different (P=0.000);tumor Ki-67 labeling index and minimum ADC value of solid part wasnegatively correlated (r=-0.754,P＜0.05).Conclusion:DWI can obtained the ADCmap of astrocytic tumors,which reflect the limited degree of movement of watermolecules,and solid tumor part of water molecules is limited by the extent of theirhistological grade was negatively correlated,therefore we will be able to assess thelevel of tumor pathology through detection of the minimum ADC value.MinimumADC value of solid part can reflect the degree of Ki-67 expression,and can be usedfor preoperative evaluation of astrocytic tumor histological grade. Partâ…¢Assessment of the pathological grade in astrocytic tumor:Comparison and combination of PWI,DWIObjective:Explore the evaluation of relevance between maximum rCBV values andminimum ADC value of pathological grade in astrocytic tumor,as well as thecomparison and combination of PWI,DWI assess the effectiveness of tumorpathology.Materials and Methods:To study the objects and methods with the firstand second part.Were drawn to the maximum part of solid tumor rCBV values andthe minimum ADC value of identifying high-grade and low-grade astrocytic tumorsof the ROC curve,area under the curve comparison between the two A_Z values.Asignificance level of 5% was assumed.Results:The assessment of high-grade(gradeⅢ～Ⅳ) astrocytic tumors,the maximum rCBV value of solid part was negativecorrelated with the minimum ADC value (r=-0.338,P=0.004);and in theassessment of low-level (gradeⅠ～Ⅱ) astrocytic tumors,the maximum rCBVvalue of solid part was showed no correlation with the minimum ADC value (r=0.131,P=0.419).To the maximum rCBV values of solid part of tumor to identify thehigh-level and low-grade astrocytic tumors,2.618 as the ideal threshold,the A_Z valueobtained under the ROC curve of 0.993,the sensitivity and specificity were98.60%,95.00%.To the minimum ADC values of solid part of tumor to identify thehigh-level and low-grade astrocytic tumors,the obtained area under the ROC curveA_Z value of 0.963,1.196×10^-3mm²/s as an ideal threshold,the sensitivity and thespecificity were 90.60%,84.30%.Joint part of the same solid tumor the maximumrCBV values of and minimum ADC value of histological grade astrocytic tumorassessment,according to the first and second part of the chosen threshold of 2.618and the ideal 1.196×10-3mm²/s as the standard,the obtained a sensitivity of 82.9%and specificity was 97.50%.Conclusion:As the assessment of high-grade andlow-grade indicators for astrocytic tumors;in the assessment of high-grade(gradeⅢ～Ⅳ) astrocytic tumors,the maximum rCBV value of solid part was negative correlatedwith the minimum ADC value.Identification of high-grade and low-grade astrocytic tumors,the maximum rCBV value of solid part is superior to the minimum ADCvalues.Compared with a single indicator,combined with maximum rCBV values andthe minimum ADC value in the solid part as a standard,and can not improve on thehigh-level identification of tumor,but such methods in combination with its clinicalvalue.Partâ…£Assessment of the difference of ADC value in thepathological grade of astrocytic tumor:Application ofdiffusion-weighted imaging (DWI)Objective:To investigate the application of different b value diffusion-weightedimaging (DWI) of the difference between the ADC value (ADC_difference) to assessvalue in the pathological grade of astrocytic tumors.Materials and Methods:Aprospective study of 33 cases supratentorial astrocytic tumors confirmed by surgeryand pathology,all cases were underwent routine MRI,PWI and DWI and different bvalue scan by using Siemens 3.0T MRI system.In 33 cases of astrocytic tumors,low-grade (gradeⅠ～Ⅱ) were 8 cases,the high-grade (gradeⅢ～Ⅳ)were 25cases (of which 10 cases of tumor gradeâ…¢,â…£-grade tumors in 15 cases).We obtaindifferent b value ADC map on the workstation,pseudo color Fig of ADC_difference byusing ADC map data of 50s/mm² minus ADC map data of 3000s/mm².On the basisof conventional and contrast MRI scan,choose the solid part of tumor on the ADC_difference map,place ROI which reflect the highest signal intensity of the color parts.Comparsion of different levels of ADC_difference were assessed by analysis of variance;comparison between the two groups by using t test.Linear correlation analysis wreeassessed by Pearson correlation method.A significance level of 5% was assumed..Results:The highest ADC_difference of gradeⅠ～Ⅱ,â…¢andâ…£were (0.91±0.07)×10^-3mm²/s,(1.81±0.38)×10^-3mm²/s and (2.36±0.32)×10^-3mm²/s,significantdifference of the highest ADC_difference were showed among the solid part of astrocytictumors (F=59.336,P=0.000).The highest ADC_difference between low-grade (gradeâ…  ～Ⅱ) and high-grade(gradeⅢ～Ⅳ) also showed a significant difference (t=7.907,P=0.000).In astrocytic tumors,the highest ADC_difference of solid part and pathologicalgrade were significant positively correlated.High-grade (gradⅢ～Ⅳ) astrocytictumors,the highest ADC_difference of solid part was significant positive correlated withmaximum rCBV values (r=0.829,P=0.000),while in low-level (gradeⅠ～Ⅱ)tumor was no significant correlation (r=0.259,P=0.536).Conclusion:In this paper,we applied different b value of ADC_difference methods for the assessment of astrocytictumors of the pathological level at home and broad.ADC_difference maps were obtainedby application of a small b value (0,50 s/mm²) and large b values (0,3000s/mm²),which reflect microcirculation and provide perfusion information.Differentpathological grade of astrocytic tumors is part of the difference between the highestADC_difference,so this method can be used for preoperative assessment of tumor grade.ADC_difference method is simple,easy and prompt access to results,which is expected tobecome a new technique reflect microcirculation reperfusion of lesions.