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ABSTRACT

Neuroimaging allows noninvasive evaluation of the anatomy, physiology, and function of the brain. It is widely used for diagnosis, treatment planning, and treatment evaluation of neurological disorders as well as understanding functions of the brain in health and disease. Neuroimaging modalities include X-ray computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), positron emission tomography (PET), electroencephalography (EEG), and magnetoencephalography (MEG). This paper presents an overview of the neuroimaging research in Iran in recent years, partitioned into three categories: anatomical imaging anatomical image analysis and functional imaging and analysis. Published papers reflect considerable progress in development of neuroimaging infrastructure, hardware installation and software development. However, group work and research collaborations among engineers, scientists, and clinicians need significant enhancement to optimize utility of the resources and maximize productivity. This is a challenge that cannot be solved without specific plans, policies, and funding.

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Introduction: A fixed hemodynamic response function (HRF) is commonly used for functional magnetic resonance imaging (fMRI) analysis. However, HRF may vary from region to region and subject to subject. We investigated the effect of locally estimated HRF (in functionally homogenous parcels) on activation detection sensitivity in a heroin cue reactivity study.
Methods: We proposed a novel exploratory method for brain parcellation based on a probabilistic model to segregate the brain into spatially connected and functionally homogeneous components. Then, we estimated HRF and detected activated regions in response to an experimental task in each parcel using a joint detection estimation (JDE) method. We compared the proposed JDE method with the general linear model (GLM) that uses a fixed HRF and is implemented in FEAT (as a part of FMRIB Software Library, version 4.1).
Results: 1) Regions detected by JDE are larger than those detected by fixed HRF, 2) In group analysis, JDE found areas of activation not detected by fixed HRF. It detected drug craving a priori “regions-of-interest” in the limbic lobe (anterior cingulate cortex [ACC], posterior cingulate cortex [PCC] and cingulate gyrus), basal ganglia, especially striatum (putamen and
head of caudate), and cerebellum in addition to the areas detected by the fixed HRF method, 3) JDE obtained higher Z-values of local maxima compared to those obtained by fixed HRF.
Conclusion: In our study of heroin cue reactivity, our proposed method (that estimates HRF locally) outperformed the conventional GLM that uses a fixed HRF.

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Introduction: about 20% to 30% of patients with epilepsy are diagnosed with drug-resistant epilepsy and one third of these are candidates for epilepsy surgery. Surgical resection of the epileptogenic tissue is a well-established method for treating patients with intractable focal epilepsy. Determining language laterality and locality is an important part of a comprehensive epilepsy program before surgery. Functional Magnetic Resonance Imaging (fMRI) has been increasingly employed as a non-invasive alternative method for the Wada test and cortical stimulation. Sensitive and accurate language tasks are essential for any reliable fMRI mapping. 
Methods: The present study reviews the methods of presurgical fMRI language mapping and their dedicated fMRI tasks, specifically for patients with epilepsy.
Results: Different language tasks including verbal fluency are used in fMRI to determine language laterality and locality in different languages such as Persian. there are some considerations including the language materials and technical protocols for task design that all presurgical teams should take into consideration.
Conclusion: Accurate presurgical language mapping is very important to preserve patients language after surgery. This review was the first part of a project for designing standard tasks in Persian to help precise presurgical evaluation and in Iranian PWFIE.