Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download magnetic resonance imaging - Scientific Research Computing
Document related concepts
Transcript
MAGNETIC RESONANCE IMAGING 2003 Noble Prize Laureates in Physiology or Medicine Paul C. Lauterbur and Peter Mansfield Noble Prize 6 October 2003 Press Release The Nobel Assembly at Karolinska Institute has today decided to award The Nobel Prize in Physiology or Medicine for 2003 jointly to Paul C. Lauterbur and Peter Mansfield for their discoveries concerning “magnetic resonance imaging” “for their discoveries concerning magnetic resonance imaging” Paul C. Lauterbur ½ of the prize USA University of Illinois Urbana, IL, USA. b. 1929 Peter Mansfield ½ of the prize United Kindom University of Notingham United Kingdom. b. 1933 Paul C. Lauterbur born May 6, 1929 in Sidney, Ohio, USA. 1951 B.S. in Chemistry, Case Institute of Technology, Cleveland 1962 Ph.D. in Chemistry, University of Pittsburgh, Pennsylvania 1969-85 Professor of Chemistry, Radiology, New York University at Stony Brook 1985-90 Professor, University of Illinois, College of Medicine at Chicago 1985-Professor and Director, Biomedical Magnetic Resonance Laboratory, University of Illinois, College of Medicine at Urbana, IL. Peter Mansfield born October 9, 1933. 1959 B.Sc. Queen Mary College, University of London 1962 Ph.D. Physics, University of London 1962-64 Research Associate, University of Illinois. 1964 Lecturer, University of Nottingham. 1968 Senior Lecturer, University of Nottingham. 1972-73 Senior Visitor, Max Planck Institut für Medizinische Forschung, Heidelberg 1979- Professor, University of Nottingham. History of MRI Late 1800’s November 5, 1895. William Roentgen discovered X-rays. Roentgen discovered that: X-rays travel in straight lines, could not be refracted or reflected did not respond to magnetic or electric field. February, 1896, X-rays were being used clinically in the United States. History of MRI In the 1930’s, a physics phenomenon was discovered, called nuclear magnetic resonance or NMR. Felix Bloch, working at Stanford University, and Edward Purcell, from Harvard University, discovered NMR. In NMR nuclei were placed in a magnetic field, they absorbed energy in the radiofrequency range of the electromagnetic spectrum, and reemitted this energy when the nuclei transferred to their original state. History of MRI This phenomenon was termed NMR as follows: "Nuclear" as only the nuclei of certain atoms reacted in that way; "Magnetic" as a magnetic field was required; "Resonance" because of the direct frequency dependence of the magnetic and radiofrequency fields. History of MRI For their discovery of NMR Bloch and Purcell were awarded the Nobel Prize for Physics in 1952. Use of NMR to investigate the chemical composition and physical structure of matter. Relaxation times, T1 and T2. T1: Time taken by nuclei in test samples to return to their natural alignment T2: Duration of the magnetic signal from the sample. History of MRI In 1970s Raymond Damadian, proposed that each tissue in the body has a different relaxation time, but cancerous tissue has an abnormally long relaxation time. He believed that the NMR could be used as an “external probe for the internal detection of cancer” Damadian presented first commercial NMR scanner at the annual meeting of the American Roentgen Ray Society in 1980. History of MRI Paul C. Lauterbur determined the origin of the radio waves by analysis of their characteristics. Discovered the possibility to create a twodimensional picture by introducing gradients in the magnetic field. In 1972, obtained the first MRI. History of MRI Pater Mansfield further developed the utilization of gradients in the magnetic field. Signals could be mathematically analyzed. Showed how extremely fast imaging could be achievable. In 1976, he and his colleagues created the first MRI of a human body part, a finger. What is an MRI? Magnetic Resonance Imaging (MRI) :safe and noninvasive test. Diagnostic technique :uses strong magnetic field and pulses of radio waves. Produces pictures of structures inside the body. Images :slices of an organ or part of body. MRI’s computer: 3-D images. How it works? Body :strong magnetic field. Machine uses :strong magnetic field and pulses of radio waves. Machine creates an image :how hydrogen atoms react. Usually images are created as single slices of organs or structures. MRI computer combine them to give a 3 D image. Using Our Body’s Magnets Because of predictions from physics and math we know there are very weak magnets in all living tissues These magnets are atoms with unpaired numbers of protons and electrons like hydrogen 1H There are billions and billions of hydrogens in your body Using Our Body’s Magnets H do not have a matched pair of neutrons and protons 1 When atomic nuclei do have perfectly matched neutrons and protons, these always arrange in pairs and rotate in opposite directions to one another With 1H, there is no match and there is a nuclear spin and slight + charge Using Our Body’s Magnets One way is to stick these very weakly magnetic tissues in a gigantic, strong MAGNET and see what happens!!!!!! This is the principle of Magnetic Resonance Imaging, (MRI) used in research and diagnostic radiology today!!!!!!!!! A moving electric charge produces a magnetic field Protons have a positive charge Protons spin Protons produce a small magnetic field No external field… Randomly aligned External field… Aligned with field Some protons align against the field… Some protons align with the field… Protons continually oscillate – always a slight excess aligning with field Aligning with field – slightly lower energy state Protons Wobble Spinning protons wobble about the axis of the external field Frequency of precession = Resonance Frequency Depends on strength of magnetic field RF Pulse Apply RF pulse at resonance frequency Protons absorb energy Protons ‘jump’ to a higher state What goes up… …must come down Energy is re-transmitted as RF signal Summary MRI Signal MRI Hardware Control Room Scanner Console MRI Hardware Scanner Liquid Helium Cooled 1.5 Tesla Solenoid Magnet Radiofrequency Transmitter/Recieiver Coil Patient Platform MRI of the Brain - Sagittal T1 Contrast TE = 14 ms TR = 400 ms T2 Contrast TE = 100 ms TR = 1500 ms Proton Density TE = 14 ms TR = 1500 ms MRI of the Brain - Axial T1 Contrast TE = 14 ms TR = 400 ms T2 Contrast TE = 100 ms TR = 1500 ms Proton Density TE = 14 ms TR = 1500 ms T1 and T2 Weighting Brain - Axial Multislice T1 Contrast in MRI T1 T2 Gadolinium The Whole Brain Atlas: http://www.med.harvard.edu/AANLIB/ Brain Tumor Laser Polarized Gas Lung Imaging Chronic Obsructive Pulmonary Disease Healthy Volunteer Advantages of MRI Diagnosing multiple sclerosis (MS) Diagnosing tumors of the pituitary gland and brain. Diagnosing infections in the brain, spine or joints Visualizing torn ligaments in the wrist, knee and ankle Advantages of MRI Visualizing shoulder injuries Diagnosing tendonitis Evaluating masses in the soft tissues of the body Evaluating bone tumors, cysts and bulging or herniated discs in the spine Diagnosing strokes in their earliest stages. Disadvantages of MRI Not for everybody. machine makes a tremendous amount of noise. require patients to hold very still for extended periods of time. Orthopedic hardware (screws, plates, artificial joints) in the area of a scan can cause severe artifacts (distortions) on the images. very expensive. Future of MRI Very small scanners. Functional brain mapping. Ventilation dynamics of the lungs through the use of hyperpolarized helium-3 gas. Image strokes in their earliest stages. Limitless future Laser Polarized Xenon MRI Functional Brain Imaging Map of Blood Flow in the Rat Brain Functional Brain Imaging Blood Oxygenation Affects Contrast Metabolism uses oxygen Contrast Reveals regions of oxygen consumption University of Minnesota http://www.cmrr.drad.umn.edu/highlight/index.html Laser Polarized Gas Images University of Virginia Sources used: http://www.nobel.se/medicine/laureate s/2003/ http://inventors.about.com/ http://www.bae.ncsu.edu/ http://www.isbe.man.ac.uk/ www.cmrr.drad.umn.edu/ Slides provided by Dr. Vankley.
