Paul Lauterbur
University of Illinois
Urbana, IL, USA
http://www.scs.uiuc.edu/chem/lauterb.htm

Peter Mansfield
University of Nottingham
School of Physics and Astronomy
Nottingham, United Kingdom
http://www.magres.nottingham.ac.uk/~mansfield/

Magnetic resonance imaging, MRI, is now a routine method within medical diagnostics. Worldwide, more than 60 million investigations with MRI are performed each year, and the method is still in rapid development. MRI is often superior to other imaging techniques and has significantly improved diagnostics in many diseases. MRI has replaced several invasive modes of examination and thereby reduced the risk and discomfort for many patients. We use this technique for diagnosis of hundreds of patients every day in neuroradiology at the University of Rochester. Imaging of human internal organs with exact and non-invasive methods is very important for medical diagnosis, treatment and follow-up. This year's Nobel Laureates in Physiology or Medicine have made seminal discoveries concerning the use of magnetic resonance to visualize different structures. These discoveries have led to the development of modern magnetic resonance imaging, MRI, which represents a breakthrough in medical diagnostics and research.

What is MR imaging

Atomic nuclei in a strong magnetic field rotate with a frequency that is dependent on the strength of the magnetic field. Their energy can be increased if they absorb radio waves with the same frequency (resonance). When the atomic nuclei return to their previous energy level, radio waves are emitted. These discoveries were awarded the Nobel Prize in Physics in 1952. During the following decades, magnetic resonance was used mainly for studies of the chemical structure of substances. In the beginning of the 1970s, this year’s Nobel Laureates made pioneering contributions, which later led to the applications of magnetic resonance in medical imaging.

MR imaging can be done at different field strengths

Improved diagnostics in cancer

MRI examinations are very important in diagnosis, treatment and follow-up of cancer. The images can exactly reveal the limits of a tumor, which contributes to more precise surgery and radiation therapy. Before surgery, it is important to know whether the tumor has infiltrated the surrounding tissue. MRI can more exactly than other methods differentiate between tissues and thereby contribute to improved surgery.

MRI has also improved the possibilities to ascertain the stage of a tumor, and this is important for the choice of treatment. For example, MRI can determine how deep in the tissue a colon cancer has infiltrated and whether regional lymph nodes have been affected.

Reduced suffering for patients

MRI can replace previously used invasive examinations and thereby reduce the suffering for many patients. One example is investigation of the pancreatic and bile ducts with contrast media injection via an endoscope. This can in some cases lead to serious complications. Today, corresponding information can be obtained by MRI.

Diagnostic arthroscopy (examination with an optic instrument inserted into the joint) can be replaced by MRI. In the knee, it is possible to perform detailed MRI studies of the joint cartilage and the cruciate ligaments. Since no invasive instrument is needed in MRI, the risk of infection is eliminated.

Professor Hans Ringertz delivers the Presentation Speech for the 2003 Nobel Prize in Physiology or Medicine at the Stockholm Concert Hall. Your Majesties, Your Royal Highnesses, Honoured Nobel Laureates, Ladies and Gentlemen, To be able to visualize the inner organs of humans without invasive techniques is of paramount importance to modern medicine. Medical imaging has undergone a dramatic development during the last 30 years. A whole series of imaging modalities have been discovered and developed, among which the development of computer assisted tomography was awarded a Nobel Prize in Physiology or Medicine in 1979. Magnetic Resonance Imaging, MRI, represents a new modality for obtaining

diagnostic medical images. The technique still has extensive potential for further development but MRI is important to monitor many diseases of most organs in the human body. Imaging with magnetic resonance is an invaluable aid in the whole healthcare chain from screening and detection, diagnosis and treatment, to follow up of diseases.

Felix Block and Edward Mills Purcell first demonstrated the physical phenomenon of nuclear magnetic resonance in 1946. These discoveries were awarded a Nobel Prize in Physics in 1952. Magnetic resonance occurs in magnetic fields between atomic nuclei and electromagnetic waves of radio frequencies. Atomic nuclei have a magnetic moment and in the magnetic field, their spin depends on the strength of the field. The direction of magnetization resulting from the magnetic moments can change. This happens when the nuclei are in resonance with radio waves of the same frequency as the frequency of their own rotation. In the same way the nuclei can send back radio waves, when there is a change in the direction of the magnetic moment.

Initially, magnetic resonance was mostly used for spectroscopy, to study structures of chemical compounds. In the early 1970s Paul Lauterbur discovered the possibility to create a two-dimensional image by introducing gradients in the magnetic field. By analysis of the characteristics of the emitted radio waves, he was able to determine their origin. This made it possible to build up images of structures that could not be visualized with other methods.

Peter Mansfield discovered further possibilities to utilize gradients in the magnetic field. He showed how the radio signals could be mathematically analysed, which made it possible to develop a useful imaging technique. Mansfield also showed how images could be achievable extremely fast using magnetic resonance. This became technically possible in clinical medicine about a decade later.

Using a metaphor, magnetic resonance spectroscopy is like listening to a radio broadcast of a symphony in the 1940s. Imaging would then be like sitting in a concert hall listening to the symphony, and not only hearing but also seeing the instruments, how they play and where they are located, like organs in the human body. And when you hear the violins, you can even recognise, as in a magnetic resonance image, a false note like a disease process in that body.

Professor Lauterbur and Professor Mansfield,

Your discoveries of imaging with magnetic resonance have played a seminal role in the development of one of the most useful imaging modality in medicine today. All indications are that it will be even more important in the future of both medical practice and research, and, above all for the patient.

On behalf of the Nobel Assembly at Karolinska Institutet, I wish to convey to you our warmest congratulations, and I now ask you to step forward to receive the Nobel Prize from the hands of His Majesty the King.

Sir Peter Mansfield received his Nobel Prize from His Majesty the King at the Stockholm Concert Hall.	Paul C. Lauterbur receiving his Nobel Prize from His Majesty the King at the Stockholm Concert Hall.

Paul Lauterbur (born 1929), Urbana, Illinois, USA, discovered the possibility to create a two-dimensional picture by introducing gradients in the magnetic field. By analysis of the characteristics of the emitted radio waves, he could determine their origin. This made it possible to build up two-dimensional pictures of structures that could not be visualized with other methods. Paul Lauterbur discovered that introduction of gradients in the magnetic field made it possible to create two-dimensional images of structures that could not be visualized by other techniques.

In 1973, he described how addition of gradient magnets to the main magnet made it possible to visualize a cross section of tubes with ordinary water surrounded by heavy water. No other imaging method can differentiate between ordinary and heavy water. Paul C. Lauterbur, PhD, is a professor of chemistry, biophysics and computational biology and bioengineering, and a distinguished university professor of medical information sciences at the University of Illinois, Urbana. He is also a professor in the Beckman Institute Magnetic Resonance Imaging and Spectroscopy Group, Urbana. Dr. Lauterbur and Sir Peter Mansfield, BSc, PhD, of Britain received the Nobel Prize for medicine in October 2003 for their contributions to MRI’s origin.

Peter Mansfield (born 1933), Nottingham, England, further developed the utilization of gradients in the magnetic field. He showed how the signals could be mathematically analyzed, which made it possible to develop a useful imaging technique. Mansfield also showed how extremely fast imaging could be achievable.This became technically possible within medicine a decade later.

Peter Mansfield utilized gradients in the magnetic field in order to more precisely show differences in the resonance. He showed how the detected signals rapidly and effectively could be analyzed and transformed to an image. This was an essential step in order to obtain a practical method. Mansfield also showed how extremely rapid imaging could be achieved by very fast gradient variations (so called echo-planar scanning). This technique became useful in clinical practice a decade later.

Controversy over the 2003 Nobel Prize in Medicine

Dr. Raymond Damadian

In 1969 Raymond Damadian was a Professor of Biophysics at the State University of New York, Downstate Medical Center in Brooklyn. He proposed using NMR signals to non-invasively exam tumors. His crucial experiments were performed at the NMR Specialties, a private laboratory in New Kensington, PA and his findings were published in March 1971 in Science (1971;71:11-51). Dr. Damadian was not first to specifically compare T1 and T2 relaxation times of cancerous tissues and various organs since this had been done before by about a dozen researchers. Sources familiar with the Nobel Committee deliberations (See article in Diagnostic Imaging, Dec. 2003) say that three issues stood in the way of Dr. Damadian being awarded the Nobel Prize. Damadian’s NMR relaxation experiments were not unique. The 2003 Prize was for the development of imaging with MR, something not contemplated in Dr. Damadian’s original Subsequent research have shown that relaxation times cannot reliably differentiate between cancer and normal tissue.