Differentiation of Brain Abscesses from Necrotic Highgrade Gliomas Using Advanced MR Imaging Techniques: A Mini Review

The accurate discrimination between brain abscesses and cystic high-grade gliomas (HGGs) is of great importance for planning adequate treatment and for estimating outcome and future prognosis. MR imaging plays an essential role in the discrimination of these two entities. However, differential diagnosis often becomes difficult as conventional neuroimaging features of brain abscess are nonspecific and may simulate those of cystic rim-enhancing mass lesions of varying etiologies including HGGs. It is well documented that cellular and vascular microenvironment of cystic cavity and enhancing rim of abscess is considerably different from that of necrotic HGG. By exploiting these unique characteristics, several studies have shown the potential of physiologic MR imaging techniques in facilitating better characterization of both of these intracranial cystic lesions. The purpose of this mini review is to summarize the basic principles and clinical role of commonly used advanced MR imaging techniques such as diffusion, perfusion MR imaging and MR spectroscopy in differentiation of brain abscesses from necrotic HGGs. Briefly, we will also discuss the potential role of emerging imaging techniques such as chemical exchange saturation transfer (CEST) in characterizing brain abscesses. We will also describe the existing challenges and limitations of using these techniques in routine clinical settings and will finally discuss possible solutions to avoiding pitfalls in data acquisition, and analysis for future studies.