الفهرس Only 14 pages are availabe for public view
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Abstract
Ring enhancing brain lesions have quite large differential diagnosis inculding neoplasm, abscess ,tumefactive demylination and others. The conventional MRI and CT beside the clinical presentation may not be enough for establishing a clear diagnosis. The MRS is useful in the diagnosis by the detection of certain brain metabolites such as choline, Amino acids, NAA .. etc and calculation of their absolute and relative concentration in the form of spectrum which is an indirect evaluation of the lesion{u2019}s metabolism, since specific spectroscopic profiles exist for most of these lesions. Twenty patients with ring enhancing brain lesions were evaluated by MRS; each patient underwent conventional contrast enhanced MRI. On the basis of MR examinations, volumes of interest for MRS were placed at the center of the lesions. Quantitative analysis of spectra were done for amino acids, myoinositol, choline, creatine, N acetyl aspartate, alanine, lipid and lactate. The data was recorded for peaks and was used to calculate the ratios Cho / NAA and Cho / Cr which were analyzed by the radiologist and compared with pathology or aspiration biopsy or on the base of clinical symptoms, improvement in the follow up imaging after antibiotic therapy and laboratory data. In this study, MRS accurately diagnosed 16 out of total 20 cases. It detected 7 cases with abscess of total 8 cases finally diagnosed as brain abscess, also detected 9 cases with tumor of total 10 cases finally diagnosed as tumor. There were 2 cases which MRS suggested tumor while the final diagnosis was multiple sclerosis and tuberculous abscess. In this study, most patients with brain abscess showed amino acids in addition to lactate, succinate and acetate. Choline was detected in most patients with brain tumors in addition to lactate or lipid