ROLE OF ADVANCED MAGNETIC RESONANCE IMAGING TECHNIQUES IN DISTINCTION BETWEEN CEREBRAL ABSCESSES AND HIGH-GRADE NEOPLASMS.

• Distinguishing between cerebral abscess and rim-enhancing tumor is a problem that is encountered frequently by radiologists. Conventional contrast-enhanced MRI reveals ring enhancement of a brain abscess that is similar to the ring enhancement of a necrotic high-grade glioma or metastasis.
• Advanced MRI techniques (DWI, MRS and DSC MR perfusion) may be used to differentiate between cerebral abscesses and high grade brain neoplasms.
• DWI is an advanced MRI technique that provides the physiological nature of the disease based on motion of water molecules across cell membrane.
• DWI allows assessment of the cellularity of the lesion non-invasively, as cellular and subcellular elements significantly impede the mobility of water molecules, thus densely cellular lesions show restricted diffusion and hence low ADC values.
• Magnetic Resonance spectroscopy (MRS) is a non-invasive diagnostic test for measuring biochemical changes in the brain, it MRS is capable of differentiating normal from pathologic brain.
• Dynamic susceptibility contrast (DSC) perfusion MRI is a technique that allows derivation of relative cerebral blood volume (rCBV) maps on the basis of the susceptibility effect related to passage of MRI contrast material through tissue.
• It provides noninvasive physiologic measurements of tumor vascularity and relative cerebral blood volume (rCBV) maps, which can be used to identify and quantify areas of neovascularization.
• We try to evaluate the role of advanced MRI techniques (DWI, MRS, DSC PERFUSION) to reach a final diagnosis in a case of brain abscess versus a cystic or necrotic tumor.