An Investigation Of The Value Of Diffusion Tensor Imaging In The Differential Diagnosis Between Malignant Gliomas And Metastasis Tumors

Background and purposeMalignant gliomas and metastatic tumors are the most two common brain tumors in adult. The incidence rate for mail and femail patient is fairly. As is known to all, Glioma is the most common primary brain tumor with occupying 40%～50% of primary brain tumors. And gliomas are divided into four classes according to World Health Organization (WHO) classiffication of tumours of the central nervous system:in which gradeⅠ～Ⅱfor low-grade gliomas, gradeⅢ～Ⅳfor high-grade gliomas. Metastases occupy 40% of brain tumors, in which 25～30% are solitary ones. Imaging examinations, especially computerized tomography (CT) and magnetic resonance imaging (MRI) play an important role in diagnosis of the two kind tumors, and could provid significant informations not only about the localization but also in qualitative aspact. Particularly, having no ionizing radiation, high soft tissue resolution and multi-dimensional, multi-sequences imaging, MRI has gradually become a routine inspection items for brain tumors. In clinical work, however, the differential diagnosis of solitary metastasis and gliomas faces certain difficulties if only relying on conventional CT and MRI examinations. As it is different in the biological behavior, clinical course, treatment options and prognosis of these two kind tumors, it is particularly important for us to have a right preoperative diagnosis and differential diagnosis between them.In recent years, with the developement of MRI equipment and renovation of computer level, advanced MRI technology and the application of the original sequences is also increasingly used. Diffusion tensor imaging (DTI) is based on echo-planar imaging (EPI) technology, provides us to observe the microcosmic movement of water molecules in micro-organization in vivo. With fast scanner speed, application of muti-parameters, such as the fractional anisotropic (FA), apparent diffusion coefficient (ADC), volume ratio(VR), exponential attenuation(ExAt), eigenvalue(E1, E2, E3). Now DTI have become a hot spot in clinical work, especially is widely used to diagnose brain white matter lesions, optic neuropathy, and brain tumors.This paper aims to explore the values of multi-parameters of DTI sequence in the differential diagnosis between malignant gliomas and solitary brain metastases before operation, and help clinician develop treatment programs.Materials and methodsIn this study subjects were divided into two groups, both of supratentorial tumors:malignant glioma group and the group of metastatic tumors. While, malignant glioma includes glioblastomas, glioma WHOⅢ～Ⅳgrade, gliomas WHOⅡ～Ⅲgrade with obvious edema, and gliosarcoma.All the 43 cases are confirmed by pathology, disease history, or clinical follow-up.All patients were examed by a Siemens 3.0T MRI scanner and they were all accepted routine MRI, DWI, and DTI. After scanning, We transport diffusion tensor images into Nuro 3D and select different regions of interest to get FA value, ADC value, VR value, ExAt value, E1, E2, E3 value, including parenchyma of tumors, immediate peritumoral edema, distant edema and the contralateral hind limbs of internal capsule or the normal signal hind limbs of ipsilateral internal capsule if the patient has bilateral lesions in the hemisphere. The comparative ratios of parameters, including ADC, FA, VR, ExAt, E1, E2 and E3 of tumor, immediate and distinct peritumoral edema to the hind limbs of internal capsule for each tumor type, then the comparisions of ratios between two type tumors were conducted using the two independent samples t test. While the comparisons of tumor and peritumoral tissues in the same type tumors were conducted using the single-factor analysis of variance or K-S rank sum test.Results(1) Malignant gliomas are 27 cases, including 11 glioblastoma,11 glioma WHOⅢ～Ⅳgrade,2 astrocytomas WHOⅡ～Ⅲgrade,1 oligodendrocyte cell tumor of WHOⅡ～Ⅲgrade,1 mixed glioma(astrocytomas and oligodendrocyte), and 1 gliosarcoma. There are 4 cases of glioma patients with multiple brain lesions,1 patients with 2 lesions in bilateral frontal lobes,1 patient with 2 lesions in right frontal lobe,1 patient with 2 lesions in the left temporal-occipital lobe,1 patients with 2 lesions in the right temporal-occipital lobe. The other 4 lesions are get away for too small or quite benign. 16 cases metastatic tumors, there are 21 lesions in all, in which,7 cases are solitary,9 cases are multiple lesions. Aslo, because the lesions are too small,2-3 bigger lesions are selected in each cases.(2) Image performance①FA map:Both the solitary and edema of malignant glioma and metastasis appeared as gloomy comparied to the normal white matter. ②ADC map:For malignant gliomas:19 solitaries shows iso-intensity,5 ones performance as lower intensity,3 tumors are as higher signal. For edema,23 shows higher signals and 4 display as low or iso-intensity. And cystic change shows high signals. For metastasis,12 tumors are iso-intensity,8 tumors show low signal and 1 is high signal;as is talking to edema,17 cases are high signals and 4 are low signals.③VR map:Tumors and peritumoral edema appeared high signals, while the white matter fiber showed low signal, there are no white matter fibers in the tumor areas, white matter fiber in peritumoral edema showed rarefaction, mutilation, change of direction.④ExAt map:Solid part of the 2 types of tumors presented iso-signal or slightly lower than the brain parenchyma signal, the cystic parts of tumors and edema displayed significantly lower signal.⑤E1, E2, E3 map:The solid part of 47 cases of on E1 map were slightly lower than the normal white matter,and 1 malignant glioma showed higher than normal white matter; while the cysitic part, necrosis and edema ware all showing obviously high signals. The solid part of the 2 types tumors on E2 and E3 maps showed slightly high or iso-signals. The signals of peritumoral edema are visible high. (3) Parameter values analysis①ADC ratio:There was a statistic difference with the immediate peritumoral edema between the two type's tumors with P=0.036. For the in-group comparisons, there were significant differences among the parenchymal, immediate and distinct peritumoral edema of both glioma group and metastatic tumor group with P< 0.05.②FA ratio:There was a statistic difference with the parenchemal of the tumors between the two types with P=0. FA ratios can not differientiat the parenchyma and edema of gliomas, while for metastasis, there were significantly difference among parenchyma, immediate peritumoral edema and distinct edema. ③VR ratios can help to differentiat the solid part of the two kind of tumors with P <0.05. For gliomas, VR ratio can not different the three kind of natures(solid,immediate edema and distinct edema). For metastasis, VR ratios can tell the tumor and the distinct peritumoral edema.④ExAt ratios can not provide statistic significance between the two type tumors with the three natures of lesions. We find that the measurements of ExAt ratio can well distinguish the tumor, immediate peritumoral edema and distinct peritumoral edema of both tumors.⑤There are no statistic significances of El or E2 ratios between the two type tumors with solid part and peritumoral edema, but regarding to solid part of tumors and immediate peritumoral edema, E3 ratios can help to differientiat the two-type tumors. For the gliomas and metastasis, the three ratios all can help to discern the parenchyma, immediate peritumoral edema and distinct edema with P<0.05.Conclusions1. FA ratio, VR ratio and E3 ratio can help to differential malignant gliomas and metastasis in the parenchyma part.2. ADC ratio, E3 ratio are statistically differente in the immediate peritumoral edema between the both type tumors. 3. ADC ratio, ExAt ratio, E1 ratio, E2 ratio, E3 ratio can distinguish the different nature of the lesions of malignant gliomas (enhanced parenchyma of tumor, immediate and distinct peritumoral edema.)4. VR ratio can differentiate between parenchyma of tumor and distinct peritumoral edema of metastatic tumor; FA ratio, ADC ratio, ExAt ratio, E1 ratio, E2 ratio, E3 ratio can be well distinct among the enhanced part, immediate peritumoral edema and distinct peritumoral edema of metastatic tumor.5. DTI can help to differentiate malignant gliomas from brain metastatic tumors before operation.