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www.totoku.eu Color Display Megapixel C M Y CM MY CY CMY K EuHos_Dec15.pdf 1 11.12.2015 10:53:42 www.healthcare-in-europe.com 15RADIOLOGY Functional neuroradiological MRI procedures Watching the brain at workDifferent sequences and contrasts already make MRI an extremely powerful imaging procedure. Through the addition of functional measuring procedures the technology really comes into its own. With the help of functional MRI it is possible to visualise perfusion patterns and metabolic activities that allow comprehensive conclusions about physiological processes. Medical physicist and Private Docent Dr Raimund Kleiser, Head of the Centre for Medical Imaging at the Wagner-Jauregg Provincial Neuropsychiatric Clinic in Linz, Austria, reports when and where functional MRI procedures are used in neuroradiology today The term functional MRI (fMRI) pro- cedures normally refers to perfusion- and diffusion-weighted imaging as well as BOLD (Blood-Oxygenation- Level Dependent) Imaging. The lat- ter provides insights into neuronal activities in the brain by measuring O2 content in red blood cells, and is less common in clinical practice. Measuring tissue damage from acute stroke One neurological application that would now be unthinkable without functional MRI measurements is the diagnosis of acute stroke. Next to the standard sequences diffusion- and perfusion-weighted measure- ments can provide important addi- tional information about the extent of tissue damage within minutes, which is of significant help for deci- sions on treatment. ‘Both measure- ments deliver important additional information by allowing us to inter- relate the respective extent of the infarction volume,’ Raimund Kleiser explains. ‘When the perfusion area is larger than the diffusion area, i.e. the presence of a so-called mis- match, this is a sign that perfusion in this area still works via collater- als, even though it may be delayed. In this case the tissue can possibly still be saved through the early start thrombolytic therapy, or through surgical intervention.’ Perfusion MRI is also used as a standard in neuro-oncology, where it provides additional data on physiology and haemodynam- ics. As higher-grade glioma show increased angiogenic activity com- pared to low-grade glioma, perfu- sion parameters enable analysts to draw improved conclusions as to the grade of malignity, patient out- come and treatment response. ‘Functional imaging is also of great importance in the context of preoperative planning of tumour removal,’ the medical physicist adds. ‘The objective for such sur- gical interventions should always be to remove the tumour as com- prehensively as possible without damaging important centres in the brain responsible for language, the sensorimotor system and memory. These important centres, which may be in close proximity to the tumour to be removed, can be identified and localised through the BOLD imaging procedure and avoided in a safer manner. The language centre has an exceptional position because, unlike many other centres, it is unilateral: for right-handed individuals it is located in the left half of the brain and for left-handed people it is part- ly unilateral in the right or the left half of the brain, and in some indi- vidual cases it is bilateral as well.’ Pre-surgical clarification for brain tumours is one of the most impor- tant indications for BOLD Imaging. Meanwhile, the procedure is now also being used for other neurologi- cal indications, such as the differen- tial diagnosis of psychiatric diseases such as schizophrenia or depression. This could result in an entirely new approach to these diseases, which may even lead to improved medical understanding of their mechanisms, the expert reports: ‘When it comes to treatment of these diseases, with medication in particular, we are hoping to achieve a better under- standing of when and why biody- namic changes occur or not.’ Almost totally confined to scientific research so far However, BOLD Imaging is pre- dominantly in use in university hospitals, and even there almost exclusively for scientific research. The reason is its complexity and elaborateness. Apart from the tech- nological prerequisites, the deter- mination of fMRI paradigms – i.e. the conceptual formulation for the stimulation of networks – is a dif- ficult task. The brain, says Kleiser, reacts extremely sensitively to just the smallest deviation to instruc- tions. ‘There is a difference between telling someone: “Please try to solve this task the best you can!” or: “Please try to solve this task as quickly as possible!” Completely different processes will happen in the brain.’ Communication with coma patients BOLD Imaging is also very time- consuming. Examining neuronal activities in certain parts of the brain, and maintaining the statistical significance, means measurements have to be repeated several times. Therefore, depending on the indica- tion, the examination can take up to two hours – plus the time spent on evaluation of the data collected. It is difficult to predict exactly how BOLD Imaging will continue to develop, Kleiser points out, but: ‘Even now, the possibilities of what can be achieved are impressive. With the additional help of special- ist software it has, for instance, even been possible to communicate with coma patients,’ he reveals. ‘The BOLD imaging procedure may not be of great benefit for the masses, but there are individual groups of patients for whom it will be of great benefit indeed.’ Next to the standard sequences, within minutes diffusion- and perfusion-weighted measurements deliver important additional information about the degree of tissue damage, providing decisive assistance for treatment decisions BOLD (Blood-Oxygenation-Level Dependent) Imaging provides information about neuronal activities in the brain by measuring the oxygen content in red blood cells Medical physicist Raimund Kleiser worked at the University Hospital Düsseldorf and the University Hospital Zurich before joining the Institute for Radiology at the Wagner-Jauregg Provincial Neuropsychiatric Clinic (man- aged by Dr Johannes Trenkler) in 2008. In 2011, Kleiser’s habilitation treatise on Experimental Radiology focused on ‘Imaging of neurophysiological processes with fMRI: saccadic eye movements and clinical applications’. In 2014 he became responsible for the organisa- tional management of the newly founded Centre for Medical Imaging at the Linz Neuropsychiatric Clinic, which combines specialist expertise from different areas of neuroscience with functional imaging. Editor-in-Chief: Brenda Marsh Art Director: Olaf Skrober Managing Editor: Sylvia Schulz Editorial team: Sascha Keutel, Marcel Rasch Senior Writer: John Brosky Executive Director: Daniela Zimmermann Founded by Heinz-Jürgen Witzke Correspondents Austria: Michael Kraßnitzer, Christian Pruszinsky. China: Nat Whitney France: Annick Chapoy, Jane MacDougall.Germany: Anja Behringer, Annette Bus, Walter Depner, Bettina Döbereiner, Matthias Simon, Axel Viola, Cornelia Wels-Maug, Holger Zorn. Great Britain: Brenda Marsh, Mark Nicholls. Malta: Moira Mizzi. Poland: Pjotr Szoblik. Russia: Olga Ostrovskaya, Alla Astachova. Spain: Mélisande Rouger, Eduardo de la Sota. Switzerland: Dr. André Weissen. USA: Cynthia E. Keen, i.t. Communications, Nat Whitney. Subscriptions Janka Hoppe, European Hospital, Theodor-Althoff-Str. 45, 45133 Essen, Germany Subscription rate 6 issues: 42 Euro, Single copy: 7 Euro. Send order and cheque to: European Hospital Subscription Dept Printed by: WVD, Mörfelden-Walldorf, Germany Publication frequency: bi-monthly European Hospital ISSN 0942-9085 Representatives China & Hongkong: Gavin Hua, Sun China Media Co, Ltd. 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