الفهرس 
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Abstract
he first generation of brain imaging techniques has perfected our ability to visualize macroscopic structural lesions. For many disorders of the brain, however, dysfunction is caused by impaired neuronal physiology more than by altered gross anatomy.
Because of this patho-physiological feature, many of these disorders cannot be visualized with ‘structural’ imaging, and are even invisible under the microscope. By perfecting the ability to visualize physiological dysfunction, the next generation of brain imaging – functional imaging – will not only revolutionize the clinical management but also contribute to our basic understanding of this class of disease.
Neurosurgery in functionally important brain sites carries a high risk for surgery induced neurological deficits. Reduction of morbidity associated with treatment is of utmost importance, neurosurgery aims to eliminate as much of the lesion as safely possible by maintaining important functions of the brain. This is achieved by application of new diagnostic technologies like fMRI which plays an important role in this field.
Functional MR imaging can be used to identify eloquent cortical regions, it enables the surgeon to take therapeutic decisions and to advise the patient carefully about the risks and also the benefits of the procedure. In certain patients, surgical time may be shortened, the extent of resection may be larger, and the craniotomy size may be smaller.
The field of fMRI is rapidly finding clinical application and is exciting scientists from a range of disciplines including neurologists, psychiatrists, and psychologists. Also pediatricians may benefit greatly from it as fMRI shows promise in the investigation and follow up of children with a variety of neurological and psychiatric disorders. These include autism, dyslexia, speech delay, and attention deficit hyperactive disorder (ADHD). And new applications are emerging every day.
FMRI has many advantages over other non-invasive methods of mapping cortical function. It provides both structural and functional information with the same imaging modality. Localization is possible even in the presence of local pathology including arteriovenous malformations and cavernous angiomas. It doesn’t involve radiation exposure or radioactive isotopes injection, making it safe for the subject. It has excellent spatial and good temporal resolution. It is easy for the experimenter to use. Also additional invasive diagnostic testing (e.g., Wada testing) can be avoided by using functional MR imaging.
Image quality is always important in MRI, since artifacts can be misleading to a clinician trying to interpret results. Motion artifact is the most important and can be a major problem and therefore patient cooperation and stable head fixation is imperative
No single imaging method provides all of the information desired, MRI is in many respects the leading methodology, in part because the same basic technology supports a wide range of techniques that can probe many different aspects of physiology and anatomy. A multi-modal approach is perhaps most likely to become an effective alternative to invasive mapping.
In conclusion, fMRI opens up a new diagnostic field of neuroradiology, with a shift from strictly morphological imaging to measurement and visualization of brain function. It is feasible for clinical routine neuroimaging and provides important diagnostic information noninvasively that is otherwise unavailable. Preoperative fMRI is safe, valid, and reasonably accurate to localize eloquent cortical regions so that the surgeons may plan their approach strategy. This technique also allows the establishment of a presurgical evaluation of risk and enables the patient to be fully aware at the moment of informed consent.
It already offers a valid alternative to invasive methods like the Wada test for establishing language dominance, and it is likely that fMRI will also replace the Wada test for assessing presurgical memory function in the nearer future. Despite the increase in its clinical applications, fMRI is still underused in the clinical field and should be performed almost routinely before surgery. The technique is suitable for accessing many aspects of human cognition.