| Purpose: To evaluate the potential of DWI and 1H-MRS in diagnosing of brain tumors and defining the tumor boundary by analysing the parameters obtained from peritumoral edema.Materials and methods: Seventy-eight patients with brain diseases(73 brain tumors,3 brain abscesses,2 inflammatory granulomas) underwent routine, diffusion-weighted and/or proton spectroscopic MR imaging. Except for seven patients with metastases and two patients with abscesses were confirmed by clinic,all patients were confirmed by pathology. Comparisons of apparent diffusion coefficients( ADC ), exponential diffusion coefficients( EDC) and metabolic ratios including of Cho/NAA,Cho/Cr,Cho/nCho were done among normal, peritumoral edematous and tumoral tissues. The peritumoral signal abnormality was divided into two regions to allow investigation of whether ADC( EDC) and metabolic ratios varies with distance of from the enhancing portion of the tumor. The immediate peritumoral area was defined to be within a 1-cm distance from the outer enhancing tumor margin; the distant peritumoral region was defined as greater than 1 cm from the tumor. ADCs(EDCs) and metabolic ratios obtained from the peritumoral regions among intracranial diseases were compared by using the one-way ANOVA. The two-way ANOVA was used to determine if there was a significant difference in the intracranial diseases among different peritumoral regions. All the statistical data were displayed as x±s,a P value of less than 0.05 indicated a statistically significant difference. Results: 1.DWI DWI signal in peritumoral edema of intracranial diseases demonstrated iso-intensity ( 66.67% ) and slight hypointensity ( 33.33% ). ADC(EDC) in immediate and distant perifocal edema of brain tumors and inflammatory diseases were significantly higher(lower) than normal white matter(P<0.02). ADC(EDC) of immediate perifocal edema were prominently significant for differentiating high-grade gliomas from low-grade gliomas, metastases, meningiomas and inflammation(P<0.05), while no significantly difference was recorded among ADC(EDC) in distant peripheral edema of all diseases(P>0.05). As for high-grade glioma, the ADC(EDC) of immediate peritumoral edema was lower (higher) than that of distant edema(P<0.05), and the former is similar to the contrast-enhancing portion(P>0.05). The ADC(EDC) in immediate, distant peritumoral edema and solid portion of low-grade glioma could not distinguish from each other(P>0.05). The ADC(EDC) of immediate peripheral edema in patients with meningioma or inflammatory disease differed significantly from those of distant peripheral edema(P<0.05). A threshold value of 14.85 for ADC in immediate perifocal edema provided 87.5%,73.17%,71.19% and 88.24% for the sensitivity, specificity, positive predictive value(PPV) and negative predictive value(NPV) for differentiation of a high-grade glioma from metastasis, meningioma and inflammation. A threshold value of 15.20 provided 93.75%,80.00%,96.77% and 66.67% for the sensitivity, specificity, NPV and PPV for differentiation of a high-grade glioma from low-grade one. 2.1H-MRS High-grade glioma showed abnormal spectra outside the area of contrast enhancement, which demonstrated elevated Cho level, normal of decreased NAA level. This spectra is prominently different from normal tissue and solid tumoral tissue. The Cho/NAA in immediate peritumoral edema of patients with high-grade glioma was higher than that seen with low-grade glioma, meningioma, metastasis and inflammatory disease (P<0.05). The Cho/NAA of immediate edema surrounding high-grade glioma is higher than that of distant edema (P<0.05). The Cho/NAA between immediate and distant edema had no statistic significance in patients with low-grade glioma, metastasis and meningioma. A threshold of 1.70 for Cho/NAA in immediate perifocal edema provided 76.92%, 86.36%, 86.96% and 76.00% for the sensitivity, specificity, PPV and NPV for differentiation a high-grade glioma from metastasis, meningioma and inflammation. A threshold of 1.35 for Cho/NAA in immediate p... |
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