Role of Contrast Enhanced MRI to Differentiate Between Neoplastic from Non-Neoplastic Ring Enhancing Brain Lesions

Abstract

Introduction: Ring enhancing lesions in MRI of the brain can be caused by different pathological conditions. The common lesions are being some primary brain tumours, abscess, granuloma, resolving haematoma and infarct. Gadolinium compounds, which are paramagnetic IV contrast media for brain imaging, are especially helpful for identification of extra-axial tumours and intra-axial lesions associated with disrupted blood-brain barrier. The enhancing ring of an abscess is usually thinner and more uniform than that found in the neoplasm. Granulomatous abscesses tend to have a thicker ring than pyogenic abscesses and have less surrounding edema. Demyelinating disorders revealed nodular pattern and incomplete ring-enhancing pattern. Infarcts often show gyral enhancement. Enhancement is uniform in immune competent patients while ring-like in immunocompromised patients. Tuberculomas on contrast administration appear as nodular or ring-like enhancing lesions. Aims: To evaluate the role of magnetic resonance imaging in distinguishing neoplastic from non-neoplastic ring enhancing brain lesions. Material and methods: Forty patients with various ring enhancing lesions in the brain were detected by MRI. The age range of the patients was 13 to 63 years. Routine sequences of T1, T2 and FLAIR spin echo sequences with IV contrast were carried out. Signal intensities on unenhanced T1- and T2- weighted images for enhanced and unenhanced solid portions, enhancement patterns, margins, cortical involvement, mass effect, and presence of vasogenic edema were studied. Result : MRI showed 20% of cases were non-neoplastic ring enhancing brain lesions in comparison with 25% revealed by histopathology.65% cases diagnosed by MRI as neoplastic ring enhancing brain lesions in comparison with =75% cases revealed by histopathology. Sensitivity of MRI in the detection of secondary neoplastic ring enhancing brain lesions was 80% and specificity was 81.8%. Percentage of primary brain tumor revealed .....