AIMS & OBJECTIVES: To assess the combined role of diffusion weighted imaging and spectroscopy in differentiating ring enhancing intracranial cystic lesions.

MATERIALS AND METHIODS: The study was conducted from Oct 2011 to Sep 2013.  Thirty (30) patients having ring enhancing intracranial cystic lesions were included in the study. 1.5 tesla MRI ACHEIVA (Phillips) with routine MRI sequences with diffusion weighted imaging (DWI) and ADC mapping followed by ADC value in the center of lesion was used. Proton Magnetic resonance spectroscopy was performed on these patients followed by T1W contrast. The radiological diagnosis was correlated with histopathological examination in 12 patients and the remaining were evaluated clinical parameters and blood tests by the clinicians.

RESULTS: Infective lesions were characterized by decreased Ch/NAA and decreased/ near normal Ch/Cr ratio as compared to ring enhancing cystic neoplastic lesions. Elevated lactate and lipid peaks were found to be characteristic for Tuberculomas.  Cystic neoplastic lesions could be differentiated from infective lesions.  Cerebral abscesses differed on the basis of elevated lactate and amino acid peaks. Brain abscesses showed high signal intensity in DWI and reduced ADC in the centre of lesion as compared to cystic neoplastic lesions.

CONCLUSIONS: The combined role of MRI with MRS and Difusion weighted imaging   is found to be useful in accurate evaluation and differentiation of intra cranial cystic ring enhancing lesions. Reduced ADC value with diffusion restriction is highly suggestive of brain abscess while in absence of restriction; magnetic resonance spectroscopy is useful in distinguishing abscess from other infective lesions and cystic neoplasms. 

KEYWORDS: ring enhancing cystic neoplastic lesions, brain abscess, diffusion weighted imaging, magnetic resonance spectroscopy.

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