The Role of Diffusion Weighted MRI in Differentiation of Intra-axial Cystic Brain Lesions

Abstract

rain abscess and necrotic tumors are most of the time difficult to differentiate on clinical information or routine conventional imaging only, and correct diagnosis is important as the medical management strategies for abscess and neoplasm are different. Correct diagnosis must be obtained before treatment of cystic brain lesions as it may alter the plan for biopsy and the need for additional investigations. This study included 24 patients (14 Males, 10 Female), conventional MRI examination was performed in all cases a peripheral enhancing or heterogenous enhancement of intra-axial cystic brain lesions of deferent pathologies were found and classified as following: 8 (33.3%) patients with brain metastasis, 7 (29.2%) patients with GBM, 5 (20.8%) with abscess and finally 4 (16.7%) patients with lymphoma. In central cystic/necrotic part of the SOL, facilitated DWI signal was seen in 100% of GBM and 75% of metastasis, while a restricted signal was seen in 60% of abscess lesions. The center of all lymphoma SOL exhibited isointense signal on DWI. An ADC value of 1.755x 10-3 mm2/s can be used as threshold to differentiate brain abscess from cystic or necrotic tumors, with ADC values below 1.755x 10-3 mm2/s diagnostic of brain abscess and ADC values above 1.755x 10-3 mm2/s diagnostic of cystic/necrotic tumors. And an ADC value of 1.955x 10-3 mm2/s noted as threshold to discrimination between center of GBM and lymphoma, as ADC values below 1.955x 10-3 mm2/s diagnostic for Lymphoma and ADC value above 1.955 x10-3 mm2/s diagnostic for GBM.