History of Magnetic Resonance From Magnetite to Magnetic Resonance Tomograph

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1 History of Magnetic Resonance From Magnetite to Magnetic Resonance Tomograph Jeannine Heller

2 Magnetic Resonance History of Magnetism History of Quantum Mechanics, Spectroscopy, Electronics & Hardware

3 History of Magnetism - Two cultures: chinese & european China 83 AD: magnetic spoon 11th century: swimming needle for compass - Pierre de Maricourt 1269: iron needles are oriented towards two points of a spherical magnetite concept of north and south pole William Gilbert 1600: De Magnete earth is magnetic adopted by Kepler, Galilei, Descartes Hans Christian Øersted 1820: electromagnetism adopted by Ampère, Faraday

4 Michael Faraday 1831: established the basis for the magnetic field model electromagnetic induction -> power generation James Clerk Maxwell: unified model of electromagnetism, light is an em wave ~1850

5 B paramagnetic substance Paul Langévin 1905: theory of para- and diamagnetism used by Weiss to explain ferromagnetism (1906) influenced Niels Bohr in the construction of his classical atom model (1913)

6 Stern-Gerlach experiment 1922: wrong theory - right experiment! 47 Ag: [Kr]4d 10 5s 1, l=0 undeflected beam B=0 defected beam d/dz B=1T/cm discovery of the quantization of angular momentum, without realizing that this quantization was due to the spinning electron!

7 Old quantum view New quantum view (Bohr-Sommerfeld) (Heisenberg) B B J=1/2 L=0, S=1/2 M=+½ J = J z M=+½ J ( J +1) They had M=-½ M=-½ B B J=1 L=1, S=0 They believed they had M=+1 M=0 M=-1 M=+1 M=0 M=-1

8 A memorial plaque mounted in February 2002 in Frankfurt

9 Uhlenbeck/Goudsmit 1925: discovery of the spin anomal Zeeman-effect (1896) could be explained (in fact Pauli had suggested a nuclear spin in 1924) Goudsmit: luck plays a very, very great role admittedly, there are cases like Heisenberg, Dirac and Einstein, there are some exceptions. But for most of us luck plays a very important role and that should not be forgotten 1926: Schrödinger/Heisenberg formulation of qm replaced the old quantum theory

10 History of Magentic Resonance two groups: Bloch (Stanford University) Purcell (MIT) But there were done experiments before: Gorter 1936: tried to measure heat produced by resonant absorption with a calorimetric method failed (but published) Rabi 1937: atomic and molecular beam methods to measure sign of magnetic moment or ist magnitude

11 Rabi s set up for beam experiments Magnets Resonance A, B, exp: C inhomogeneous C homogeneuos Fields have same direction db dz B B A B C B B oven detect db dz rf A C (removable) Visit of Gorter 1937: transitions could be introduced more efficiently by resonant absorption of rf energy in a homogeneous magnetic field placed between A and B C was changed!

12 publication 1938 first reported nuclear magnetic resonance signal (LiCl) in the footer: Rabi, Phys. Rev. 53 (1938) 318 Nobel Prize 1944 for Rabi (only)

13 Coming back to Bloch and Purcell: They used different detection methods for the resonance signal B 0 Bloch s idea: Macroscopic magnetization is tipped away from eq position by resonant absorption from an rf field Resulting magnetization, precessing about B 0 would induce an electrical signal in a coil placed along x or y The experiment 1946: Two orthogonal coils Sample: liquid water

14 Packard s idea: Only one coil for emitting and receiving Looking for unbalances in the bridge circuit Experiment 1945: Cavity resonant at 30 MHz Varying magnetic field 1 kg Paraffin as sample Bloch & Purcell: Nobel Prize in 1952 Purcell, Torrey, Pound Phys. Rev. 69 (1946) 37 Bloch, Hansen, Packard Phys. Rev. 70 (1946) 474

15 Zavoisky: tried to detect NMR signal in 1941, wasn t reproducible successful detection of electron resonance: 1 st reported observation of ESR in : E.Hahn First pulse NMR experiment 1958: B.Mims First pulse EPR experiment 1965: R.Ernst First FT NMR experiment 1976: R.Ernst First 2D NMR experiment 1986: J.Freed First 2D EPR experiment 1994: Wrachtrup, Köhler, Groenen, Borzyskowski First single molecule EPR experiment

16 The first MR Image in literature 30 years In the early 1980s:12 machines, then it went like this: < 0.5 T < 1.4 T > 1.5 T Lauterbur Nature 242 (1973)190

17 Damadian s MRI prototype in industiral metal style, 1977 today in ipod style

18 Future of MR - higher magnetic fields - use of high-temperature superconducting materials - reliance on complex computational facilities and image processing procedures -? -?