الفهرس 
AnatomyOnly 14 pages are availabe for public view
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Abstract
Background: Intracranial cystic lesions are unnatural cavities in which the continuity of the brain parenchyma is disrupted because of different pathologies such as infections and tumors containing proteinaceous fluid and/or cellular/necrotic materials
Aim of Study: The purpose of this study is to investigate the value of some MRI modalities mostly DWI and MR Spectroscopy in differentiation of the common intracranial intra-axial cystic brain lesions to help these patients benefit from the best medical management and treatment.
Patients and Methods: This is a prospective study, conducted from April 2019 till April 2021. It is included forty adult patients of either sex with a cystic/necrotic intra-axial brain lesion with variable perifocal edema and rim enhancement on post-contrast study at MRI unit, radiology department, Ain Shams University (ASU) Hospital. All examinations carried out after signing the informed consent by the patient himself or his guardian if the patient is incapacitated by any means.
Results: The ADC values at center of lesions were not uniform. We found the lowest ADC value in the center of the lesion at the abscess 0.4x10 -3 mm2 /s and the highest ADC value 3.2 x10 -3 mm2 /s found in cystic neoplastic lesion. There was a significant difference in the center ADC values of neoplastic necrotic lesions mean ADC value was 1.95±1.08 x10-3 mm2 /s and 1.15±0.65x10-3 mm2 /s found in abscess lesions, with a cut off value, sensitivity, specificity, positive predictive value (PPV) negative predictive value (NPV) and accuracy value of: 1.55, 92.9%, 91.7%, 96.3%, 84.6%and 92.5%respectively. MRS done to the forty cases the Cho/Cr, Cho/NAA and NAA/Cr mean ratios were calculated. Comparison of these ratios between the different categories. Statistically significant differences were found as regards the Cho/Cr, Cho/NAA ratios between both groups (p values <0.001**), while no statistically significant difference was found as regards the NAA/Cr ratio.
Conclusion: Diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) are useful as additional diagnostic modalities for differentiating brain abscesses from cystic or necrotic brain tumors Furthermore some MR techniques may be helpful for discrimination brain abscess from cystic or necrotic tumors , as diffusion tensor imaging (DTI), perfusion weighted imaging as well as positron emission tomography computed tomography (PET-CT). This will help to improve the accuracy of MR in differentiating brain abscess from cystic or necrotic tumors.