الفهرس 
Anatomy of the BrainOnly 14 pages are availabe for public view
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Abstract
Intracranial tumors are a significant health problem. The annual incidence of primary and secondary central nervous system neoplasms ranges from 10 to 17 per 100,000 persons.
Inflammatory diseases of the central nervous system (CNS) are playing an increasingly important role in the clinical practice of neuroradiology: Infections of the CNS frequently involve immunocompromised patients and are being accompanied increasingly more with the employment of innovative and aggressive immunosuppressive and immunomodulatory therapies.
We found that neither visual inspection nor measuring signal intensity means from T1 and T2 weighted images could differentiate between abscesses and necrotic tumours.
The abscess cavity often demonstrated a long T1 and T2 value, whereas the abscess capsule often displays shortening of both the T1 and the T2 value. Peripherally, a zone of oedema is usually present surrounding the lesion. The abscess wall usually shows a ring of enhancement following contrast administration. Unfortunately, these features are not present in all abscesses and may be seen in a variety of tumours.
The approach to imaging diagnosis, treatment and follow-up is different between the cerebral abscesses and necrotic tumours. Because conventional MRI is limited in its ability to distinguish brain abscesses from necrotic tumours, new and more advanced techniques are urgently needed.
Spectroscopy, diffusion and perfusion-weighted MRI are advanced MR techniques that are used to add important physiological and metabolic information to that obtained with conventional MRI. This study demonstrates that diffusion (apparent diffusion coefficient (ADC) values of central regions), perfusion-weighted (relative cerebral blood volume(rCBV) values of peripheral regions) and spectroscopic MR measurements can be used to demonstrate differences in cerebral abscesses and necrotic tumours.
On DWI brain abscess cavity shows high signal intensity and a low ADC value. On the other side all tumors show low signal intensities on DWI in the cystic or necrotic area, and their cystic or necrotic areas had high ADC values.
By MR spectroscopy The main characteristic features of pyogenic abscesses are the resonances of amino acids (valine, leucine, and isoleucine) (0.9ppm), acetate (1.9ppm), alanine (1.5ppm), lactate (1.3ppm), and succinate (2.4ppm).
In contrast, Spectra in patients with cystic or necrotic tumor showed only the peak attributed to lactate (1.3 ppm). Lipid (0.8-1.3ppm) may also be found in patients with a tumor.
On PWI Primary high-grade neoplasms and metastases are expected to have elevated rCBV because of intensive neoangiogenesis and high metabolism.
Cerebral abscesses have been shown to have large amounts of mature collagen and decreased vascularity, which may serve as the explanation for the lower rCBV ratios in comparison with high-grade neoplasm.
In conclusion, spectroscopic, diffusion and perfusion-weighted MRI are advanced MR techniques that are used to add important physiological and metabolic information to that obtained with conventional MRI.