fMRI Presentation


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Presentation I did on an advanced imaging modality for a Radiography class.

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fMRI Presentation

  1. 1. Functional Magnetic Resonance Imaging
  2. 2. Synopsis of MRI 1) Put subject in big magnetic field 2) Transmit radio waves into subject [2~10 ms] 3) Turn off radio wave transmitter 4) Receive radio waves re-transmitted by subject0 5) Convert measured RF data to image
  3. 3. History of fMRI The First “Brain Imaging Experiment” E = mc2 ??? Angelo Mosso Italian physiologist (1846-1910) “[In Mosso’s experiments] the subject to be observed lay on a delicately balanced table which could tip downward either at the head or at the foot if the weight of either end were increased. The moment emotional or intellectual activity began in the subject, down went the balance at the head-end, in consequence of the redistribution of blood in his system.” -- William James, Principles of Psychology (1890)
  4. 4. History of fMRI NMR -nuclear magnetic resonance Felix Block and Edward Purcell 1946: atomic nuclei absorb and re-emit radio frequency energy 1952: Nobel prize in physics MRI -1973: Lauterbur suggests NMR could be used to form images -1977: clinical MRI scanner patented -1977: Mansfield proposes echo-planar imaging (EPI) to acquire images faster fMRI -1990: Ogawa observes BOLD effect with T2* blood vessels became more visible as blood oxygen decreased -1991: Belliveau observes first functional images using a contrast agent -1992: Ogawa & Kwong publish first functional images using BOLD signal
  5. 5. MRI vs. fMRI Functional MRI MRI studies brain anatomy. (fMRI) studies brain function.
  6. 6. The Brain Before fMRI (1957) Polyak, in Savoy, 2001, Acta Psychologica
  7. 7. The Brain After fMRI (Incomplete) reaching and pointing motor control touch eye retinotopic visual maps movements grasping executive control motion near head memory orientation selectivity motion perception moving bodies static faces objects scenes social cognition bodies
  8. 8. MRI vs. fMRI high resolution MRI fMRI low resolution (1 mm) (~3 mm but can be better) one image … many images (e.g., every 2 sec for 5 mins)
  9. 9. fMRI Setup This setup allows for testing of responses to visual stimuli.
  10. 10. Actual fMRI Setup
  11. 11. How to measure neural activity?  The physiology of neural activity involves many complex processes.  MR has the capability to measure parameters related to several neural physiological functions, including:  changes in phosphorus metabolism and metabolic byproducts  blood flow  blood volume  blood oxygenation Capillary beds within the cortex 
  12. 12. BOLD  Blood Oxygenation Level Dependent (BOLD) signal  indirect measure of neural activity  Commonly used method  neural activity  blood flow  oxyhemoglobin  T2*  MR signal
  13. 13. Stimulus to BOLD Source: Arthurs & Boniface, 2002, Trends in Neurosciences
  14. 14. fMRI Activation Source: Posner & Raichle, Images of Mind
  15. 15. What is fMRI?  Functional MRI creates a series of images that capture blood oxygen levels in parts of the brain that are responsible for movement, perception, and cognition.  fMRI is becoming the diagnostic method of choice for learning how a normal, diseased or injured brain is working, as well as for assessing the potential risks of surgery or other invasive treatments of the brain.
  16. 16. What is fMRI?  Functional magnetic resonance imaging is a relatively new research tool that provides important insight into the physiology of cognition, memory, emotion and creativity.  Functional MRI is proving its worth in clinical practice and is a safe and noninvasive imaging modality that does not expose the patient to x- rays, contrast media or invasive diagnostic procedures.  fMRI, a technological variant of magnetic resonance imaging, allows researchers and clinicians literally to watch the brain in action.
  17. 17. How is fMRI Used?
  18. 18. How is fMRI Used?
  19. 19. Why is fMRI Used?  Examine the anatomy of the brain  Determine precisely which part of the brain is handling critical functions such as thought, speech, movement and sensation, which is called brain mapping  Help assess the effects of stroke, trauma or degenerative disease (such as Alzheimer's) on brain functions  Monitor the growth and function of brain tumors  Guide the planning of surgery, radiation therapy, or other surgical treatments for the brain
  20. 20. Potential Clinical Applications  fMRI, while used primarily as a research tool, does have clinical applications that span a broad range of disease processes and medical fields including:  Epilepsy  Schizophrenia  Diabetes  Overactive Bladder  Parkinson’s Disease  Depression
  21. 21. Potential Clinical Applications Epilepsy  Epilepsy is a neurological disorder of the brain that affects nearly 3 million people living in the United States.  Seizures are the outcome of abnormal electrical activity in the brain. There are many types of seizures, and their signs and symptoms depend on the part of the brain affected.  The benefits of fMRI in epilepsy surgery include the reduced need for the services of a complex medical and surgical team, reduced patient exposure to invasive diagnostic testing, reduced medical and surgical complications and reduced medical costs.
  22. 22. Potential Clinical Applications Schizophrenia  Schizophrenia, considered the most chronic, disabling and expensive mental illness, affects approximately 2.2 million people in the United States.  Functional MRI studies are helping researchers connect the clinical signs and symptoms associated with schizophrenia, such as deficits in working memory and language function, thought disorder and impaired social cognition, with decreased brain activity.  fMRI is also a source of physical clinical evidence that can help the clinician make a diagnosis, develop and monitor treatment and offer a prognosis.  Functional MRI studies eventually may help clinicians evaluate the efficacy of medical interventions.
  23. 23. Potential Clinical Applications Diabetes  Diabetes, a disease characterized by the inability to maintain normal blood glucose levels, affects more than 20 million children and adults in the United States.  Recent research using fMRI shows that, under certain circumstances, having type 1 diabetes can affect cognition.  Furthermore, there is an association between early onset (childhood) diabetes and the development of mild brain atrophy, lower non- verbal intellectual ability, and slower psychomotor speed in adulthood.
  24. 24. Potential Clinical Applications Overactive Bladder  Urinary urgency, or overactive bladder, is a common condition that affects more than 17 million people in the United States.  Physicians currently treat this condition using behavior modification to re-establish normal brain-bladder communication and medication to suppress detrusor muscle contractions.  fMRI studies have revealed the potential for drug treatment strategies.  Functional MRI research findings eventually could lead to therapeutic approaches directed at specific areas of the brain rather than the bladder.
  25. 25. Potential Clinical Applications Parkinson’s Disease  Parkinson disease (PD), a progressively degenerative neurologic illness, affects more than an estimated 1 million people in the United States.  Functional MRI studies are revealing new information about the effects of PD on the brain and behavior.  Functional MRI helps us better understand how PD disrupts spontaneous movements by showing how people learn and perform automated or quot;built-inquot; motions such as accurate typing.  More importantly, fMRI studies show that specialized training regimens help patients with PD learn how to use other parts of their brain in efforts to re-establish fluid movement.
  26. 26. Potential Clinical Applications Depression  Depression, one of the most common psychiatric illnesses in the world, affects nearly 19 million people in the United States.  Functional MRI studies are helping researchers decipher the relationship between depression and brain activity and develop evidence-based medical care strategies.  fMRI studies also could help clinicians predict which patients will benefit from cognitive behavioral therapy (CBT) that helps them stop ruminating over negative information.