الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Infection of the central nervous system can be life-threatening and hence requires early diagnostic support for its optimal management.
Routine definitive laboratory diagnostic tests can be time-consuming and delay definitive therapy.
Noninvasive imaging modalities have established themselves in the diagnosis of various neurologic diseases.
Proton magnetic resonance (MR) imaging plays an essential role in the management of patients with a wide range of neurological conditions. While conventional MR imaging provides important structural information, data on underlying brain function is often limited.
To overcome the aforementioned limitation, the development of new imaging techniques is required, in order to highlight functional or metabolic properties of brain tissue.
Proton Magnetic resonance spectroscopy (1H-MRS) is one such technique which provides a noninvasive method for characterizing the cellular biochemistry which underlies brain pathologies, as well as for monitoring the biochemical changes after treatment in vivo.
Multi-voxel technique is the preferred one as it covers wide area of the examination.
Regarding the important metabolites detected by 1H-MR spectroscopy of the brain as resonance peaks are choline, creatine, N- Acetyl Aspartate (NAA), lactate, lipid, alanine, glutamate and glutamine, myo-inositol, succinate, aminoacids and other less common metabolites.
Regarding the interpretation, the best method for accurate diagnosis is to use important ratios such as Cho/Cr, Cho/ NAA and NAA/Cho, depending mainly on intermediate TE.
This study aimed to assess the role of MR spectroscopy in diagnosis of focal brain lesion.
The study included 20 patients with brain infection at conventional MRI. All the patients underwent conventional MR study and MR spectroscopy examination. Some of lesions were histopathologically proven and matching with the diagnosis, the rest was confirmed by response to treatment, radiological and clinical follow up and laboratory investigations.
It can specify type and cause of infection by detection of certain metabolites such as amino acid (0.9 ppm) in diagnosis of pyogenic abscess and identification of lipid in tuberceloma and tuberculous abscess.
MRS had an important role in differentiation of neoplastic and non-neoplastic lesions, a threshold value of 0.95 for Cho/Cr ratio gave a sensitivity of 100% and a specificity of 73%, a threshold value of 1.25 for Cho/NAA ratio gave a sensitivity of 85% and a specificity of 57%, a threshold value of 0.45 for NAA/ Cr ratio gave a sensitivity of 71% and specificity of 84%.
MRS in this study was of great benefit in the diagnosis of different brain infections.