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List of Projects

Projects

  • fMRA, a new tool to replace DSA ?

    Principal Investigator: Dr Xavier Golay
    Contacst: Dr Xavier Golay, Esben Petersen
    Funded by: NHGA-RPR/04012
    Funding Period: August 2004 - August 2006

    Summary:

    Diagnostic imaging of the intracrania blood vessels is essential for studying a variety of brain diseases. Conventional catheter x-ray angiography (digital subtraction angiography or DSA) is the method of choice currently being used. In the present protocol, we will evaluate the possibility for a complete non-invasive method based on MRI to get similar information.


  • Collateral perfusion in first episode stroke patients measured by Regional MR Perfusion Imaging may help define patient at risk

    Principal Investigator: Dr Xavier Golay
    Contacts: Dr Xavier Golay, Dr Ivan Zimine, Esben Petersen
    Funded by: NMRC/0919/2004
    Funding Period: March 2005 – February 2008

    Summary:

    The main problem in cerebrovascular obstruction and stroke is decreased cerebral perfusion, i.e. decreased oxygen delivered to the brain of patients. Neurological deficits occurs in tissue after cerebral blood flow (CBF) falls below approximatively 20ml/100g of tissue per minute. Hence a non-invasive means of determining the underlying absolute CBF would be highly desirable.


  • Development and application of new MRI sequences for understanding of brain physiology and pathology

    Principal Investigator: Dr Xavier Golay
    Contacts: Dr Xavier Golay, Dr Ivan Zimine,Esben Petersen, Lynn Ho

    Summary:

    MR Imaging (MRI) and spectroscopic imaging (MRSI) have the capability to reveal both anatomical anf functionnal alterations of the developing and affected brain in a totally non-invasive manner. However, most of the MRI methods are still sub-optimal and could benefit from the most recent developments in the field. This is particularly important when using new equipment or very high technology MRI scanners, such as the high field system used in the Department of Neuroradiology.


  • Understanding the coupling between CBF and metabolism in interictal epileptic spikes

    Principal Investigator: Dr Xavier Golay
    Contacts: Dr Xavier Golay, Dr Ivan Zimine, Lynn Ho
    Funded by: NMRC/0855/2004
    Funding Period: September 2004 - August 2007

    Summary:

    Precise localization of the epileptic focus is a prerequisite for good surgical outcome in patients with intractable or pharmacoresistant epilepsy. Recently, new techniques have become available to depict the actual sources of interictal epileptic discharges (IEDs) by monitoring of electro-encephalogram (EEG) during functional magnetic resonance imaging (fMRI) experiments. However, inconsistent results have been published on the shape and sign of the blood oxygenation level dependent (BOLD) signal related to IEDs. This fact and the intrinsic technical difficulties of the technique are the main reasons why the success rates of such experiments are generally low, not exceeding 40-60%. Therefore, we are studying the coupling mechanisms between IEDs and metabolism in pilocarpine rat models and patients with pharmacoresistant epilepsy using ASL, VASO and BOLD fMRI. This study will provide information on the controversial relationship between energy consumption, oxygen metabolism and related hyperemia in IEDs. This will help improve the non-invasive localisation of epileptogenic foci, which is particularly difficult in patients with non-lesional, extratemporal epilepsy.


  • A MRI study of brain plasticity in patients with visual field defects

    Principal Investigator: Lynn Ho
    Contacts: Lynn Ho, Dr Xavier Golay, Dr Ivan Zimine
    Collaborators: Dr Kong Yong Goh (Eye Institute, TTSH), Prof. Bernard Sabel (University of Magdeburg, Germany)
    Funded by: Singhealth Fundation Grant
    Funding Period: July 2006 – June 2008

    Summary:

    Visual field defects resulting from lesions in or near the occipital cortex (due to stroke for example) have been considered untreatable in the past as visual pathways were considered as hard-wired and incapable of reorganization. Recently however, many publications tend to demonstrate the opposite. In particular, a very promising therapy has been put together by the group of Prof. Sabel in Germany, and is now commercialized by Nova Vision, Inc. in Florida. This method is intensive vision restoration therapy (VRT) with incremental difficulty targeted at the specific deficit of each patient. We study the physiological changes during the therapy of patients undergoing VRT using retinotopic mapping through functional MRI (fMRI) and high-resolution diffusion tensor imaging (DTI). Such information would be very useful to get a more thorough understanding of the structure-function relationship during reorganization, and could serve as a prototype to develop new kinds of therapy for restoring other essential senses resulting from brain lesions.