Perfusion-weighted imaging in differentiating ring-enhancing lesions in brain

Abstract

Context: Ring-enhancing lesions in the brain always raise questions among radiologists and given the many possible differential diagnosis, it may sometimes be difficult to reach a diagnosis with conventional magnetic resonance imaging (MRI). The introduction of advanced imaging techniques, such as perfusion- and diffusion-weighted imaging, has contributed to the differentiation. Aim: The aim of the study was to differentiate various ring-enhancing lesions in the brain using perfusion-weighted imaging (PWI) on the basis of relative cerebral blood volume (rCBV). Materials and Methods: This prospective study was conducted on 39 consecutive patients, from rural and suburban areas of Tirupati, in the time frame of 14 months and included neoplastic (24 cases) and infectious (15 cases) lesions showing ring-shaped contrast enhancement on conventional MRI. PWI was performed and the rCBV values were obtained. The final diagnosis was made by histopathology of surgical specimen (in operated cases) and on response to treatment in the form of symptom improvement and lesion clearance on follow-up imaging (computed tomography or MRI) done at 1–6 months after appropriate therapy in unoperated cases. Results: Neoplastic lesions had higher rCBV values (5.04 ± 1.86) than infectious lesions (0.90 ± 0.43) (P Statistical Analysis: We compared the rCBV values between the two groups using Student's t-test. We used receiver operating characteristic curve analysis to assess the performance of the diagnostic test. Conclusion: PWI is an efficient advanced imaging technique in ring-enhancing brain lesions and is a useful complementary tool to routine structural MRI in distinguishing between infectious and neoplastic brain lesions.