The Value Of Conventional MR And Diffusion-weighted Imaging In Diagnosis Of Meningiomas

Objective: The Purpose of this study is to verify the reliability ofroutine MR imagine to differentiate benign from atypical/malignantmeningiomas and common different sub-types.Materials and Methods: we retrospectively reviewed139patients(120cases of them have a judgment of subtype) with pathologically provenintracranial meningioma, focused on the relationship between conventionalradiologic characteristic and the grades of tumor or some specific histologicsubtypes of meningioma, we including the tumor site、tumor size、the shapeof the tumor、the degree of peritumoral edema and the signal intensity ofthe lesions on T1WI、T2WI、T2Flair, also the age and gender were to becovered.Results:Meningiomas were histologically graded as benign (n=130),atypical (n=6) and malignant (n=3). Fibrous, Meningothelial, transitional andangiomatous，microcystic were the most frequent benign sub-types (46,35,17and7，3cases, respectively).1、age、gender of the patients: There was no statistical differencebetween typical and atypical/malignant meningiomas when considering age orgender; there was a statistical significance between Fibrous andMeningothelial when considering gender，Fibrous were more commoninfemale（P=0.01）.2、size、shape and location of the tumour: tumour size did not differ significantly among pathological levels or subtypes. But there weresignificant differenc when considering shape and location, atypical/malignantmeningiomas show more “lobulated” shape (P=0.043),and always located inthe skull base compared with benign meningiomas(P=0.005); alsomeningothelial and atypical prefer occurred in the skull base than othersubtypes(P＜0.005).3、Peritumoral edema：the degree of edema by descending order ofmeningothelial、atypical、angiomatous、microcystic、 transitional、Fibrous,and there were statistical significance between meningothelial andtransitional（P=0.002）、meningothelial and Fibrous（P＜0.01)）、atypical andFibrous （P=0.023）。there was no statistical significance between benign andatypical/malignant group. The edema appeared about37.73%、78.43%、88.57%respectively according to tumor size. There exsit a positivecorrelation between tumor size and Peritumoral edema(r=0.312**、 P＜0.01).4、MR signal intensity: the signal intensity of tumor did not differsignificantly between benign and atypical/malignant group on T1WI、T2WIand T2Flair. But microcystic and angiomatous obviously show hyperintenseon T2WI、hypointense on T1WI compared to the other(P＜0.005).there wereno statistical significance on T2Flair among subtypes.Conclusions: conventional magnetic resonance shows some radiologicfeatures which were found to have helpful in determining different tumorgrades or subtypes of meningiomas,those features may predict tumor”spathobiological behavior of some subtypes. Objective: This study aims to assessed the signal characteristica ondiffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC)measurements of meningiomas whether correlated with histopathologicfindings, whether DWI and ADC maps can differentiate benign fromatypical/malignant meningiomas,even among different sub-types.Materials and Methods:Pre-operative DW MR and ADC maps werestudied of94adult patients with meningiomas, whom were pathologicallyprovend. DWI signal intensity of tumors was classified as hypo-, iso-orhyper-intense to grey matter. ADC values were measured on ADC maps bytwo neuroradiologists unaware of the histopathologic findings, the ADCvalues of each lesion were expressed as the minimum ADC(ADCmin)、meanADC(ADCmean)、and maximum ADC(ADCmax). MRI and histological findingswere compared.Results:1、The signal intensity on DWI did not reach a significantcorrelation between benign and atypical/malignant meningiomas groups. thesignal intensity of microcystic meningioma on DWI is “lighter” than otherfrequent subtypes, But there was no statistically significant(p＞0.05).2、 All ADC values were played in the form of benign VSmalignant,ADCmin(92.61±16.95VS85.42±7.11)×10-5mm2/s、ADCmea（n97.34±18.53VS89.83±7.79）×10-5mm2/s、 ADCmax(103.49±20.96VS94.52±8.14) ×10-5mm2/s. There was no statistical difference between typical andatypical/malignant meningiomas when considering ADC values,butangiomatous are higher among meningothelial、atypical、angiomatous、transitional、Fibrous and Microcystic in all ADCs (P﹤0.05),the ADC valuesof angiomatous is (122.60±20.5)×10-5mm2/s、(129.00±20.90)×10-5mm2/s、（136.71±22.16）×10-5mm2/s respectively.Conclusions: According to this retrospective study, DWI and ADCmeasurement do not seem reliable in discriminating typical andatypical/malignant meningiomas, but show useful informations in identifyingsome histological sub-types. Hence, DWI and ADC values may providadditional value in surgical or treatment planning.