The Applicative Value Of MR Diffusion Weighted Imaging In The Differential Diagnosis Of Cerebral Tumors

Backgrounds and Objective Diffusion weight imgaing (DWI) was the unique method to present the changes of the micro geometry structure of the human body, the motion of the water molecule and the temperature of the cell by performing the molecular diffusion measurement and imaging.The specifity of diffusion-weighted imaging (DWI) in the diagnosis of cerebral infarction is well established .DWI with echo-planar sequences has been applied to various brain lesions other than infarction, including brain tumors. Several studies have shown that DWI and calculation of apparent diffusion coefficient (ADC) may aid conventional MR imaging in the characterization of cerebral tumors. There are some arguments about using DWI and ADC values to distinguish the solid portion of the tumor from the peritumoral edematous region and to differentiate the tumor types or grade gliomas. Since the therapeutic approaches for the intracerebral tumors differ regarding the nature of the tumor and the grade of gliomas, the development of the imaging techniques that accurately depict these features in vivo is important for the determination of appropriate treatment strategy. As reported previously, high degree of tumor cellularity can affect water diffusibility on diffusion-weighted images. In view of these data, since different histological tumor types would have different cellularity, we carried out this study in order to research the contribution of apparent diffusion coefficient (ADC) values, relative apparent diffusion coefficient (rADC) values, exponent diffusion coefficient (EDC) values and relative exponent diffusion coefficient (rEDC) values, into differential diagnosis between several cerebral tumors.Materials and Methods One hundred and five patients with brain diseases (7groups: meningiomas ,low grade gliomas , high grade gliomas , metastasis, lymphoma, schwannoma, recurrent tumors)underwent routine and diffusion-weighted MR imaging , between Oct 2007 and Dec 2008.All the neoplasms proved pathologically. The ADC and the exponential diflusion coeficient (EDC)values were measured at the tumorous core,peritumoral edematous region, peritumoral white matter area and the contralateral white matter.The rADC and rEDC values of the tumorous core,peritumoral edematous region and peritumoral white matter were calculated.In statistical analysis, ANOVA and LSD tests were performed to determine if there are differences. All date were analyzed by SPSS 13.0 statistical software package.A significant difference was accepted if p was less than 0.05.The relationship between the various diffusion coefficient values and tumor diagnosis or grading was analyzed.Results1. Differences between the ADC values and the rADC values of low grade astrocytoma and lymphoma are significant(P<0.05); There is no statistic differences between high grade astrocytoma and lymphoma .2. ADC value and rADC value in high grade astrocytoma is significantly lower than that of low grade astrocytoma(P< 0.01). rEDC value in high grade astrocytoma is significantly higher than that of low grade astrocytoma(P< 0.01).3. For the rADC value of peritumoral edematous region of astrocytoma, significant difference was displayed when compared with that of meningioma or metastases (P< 0.05).Differences of peritumoral edematous region between lymphoma and the others are not significant(P>0.1).4. The differences between the lower and the high grade astrocytoma in peritumoral edematous region diffusion values are still need to study and research.5. DWI can help conventional MR imaging to distinguish the solid portion of the tumor from the peritumoral region.6.The minimum apparent diffusion coefficient (ADCmin) values measurements may help to differentiate the low grade astrocytoma from the high grade astrocytoma . 7. ADC and rADC values of necrotic region of the benign tumors and the malignant tumors are not significant(P>0.05).Conclusions The ADC and rADC values are very valuable in differentiating the tumor types and grading of brain glioma.The development of the imaging techniques that accurately depict these features in vivo is important for the determination of appropriate treatment strategy.