History And Science Behind Mri: Open Or Closed Case?

History and Science Behind MRI: Open or Closed Case?

Magnetic Resonance Imaging (MRI) has been called one of the most comprehensive and efficacious diagnostic imaging modalities in medical history. It became a viable clinical technique in 1982 and during its relatively short lifetime has become the primary imaging modality for investigations of the brain, spinal cord, spine, cancellous bone, and joints. It is widely used for the identification and staging of tumors, investigations of large blood vessels, and in pediatric studies. Cardiac MR, with its unique ability to provide simultaneous information about anatomy, function, and tissue character, has become a primary or complimentary modality in a wide range of pathologies, such as aortic disease, masses, congenital heart disease, ventricular function, and cardiomyopathies.

Unique technical abilities are the driving force behind the rapid clinical acceptance of MRI. It is a completely noninvasive technique capable of producing images with soft tissue contrast seventy to eighty times greater than Computed Tomography (CT) without hospitalization or the use of ionizing radiation. In addition, MR systems can directly image in the coronal, sagittal, axial, or any oblique imaging plane without repositioning (Compunet).

Felix Bloch was a theoretical physicist who, in 1946, proposed some very interesting properties for the particles, which make up the nucleus of an atom. Bloch, working at Stanford University, proposed that the protons inside the nucleus of any atom behave like tiny magnets. He mathematically described this magnetism by what are now called Bloch equations (Femano 4).

Bloch's equations explain that tiny charged particles in the nucleus of an atom behave as though they spin on an imaginary axis like a top. This causes them to make a very small magnetic field. The connection between atomic particles and magnetic fields was very important to the future development of MRI (Femano 5).

At about the same time, Edward Purcell measured an important physical phenomenon for which he coined the term "nuclear Magnetic absorption

of energy in bulk materials". To put it simply, he showed that by passing the right type of energy through a material, the material would then respond by giving off energy of its own that he could measure. This is the principle of resonance, which is essential for MRI to work. Resonance is a physical principle that allows the efficient transfer of energy from one object to another, causing the receiving object to vibrate at the same frequency as the sender. Bloch and Purcell shared the Nobel Prize in Physics in 1952 for their significant contributions to the betterment of mankind (Femano 5).

Dr. Raymond Damadian, is credited as being the inventor of the first MRI machine, who received the National Medal of Technology and was inducted into the National Inventors Hall of Fame for his pioneering work. In 1972, Dr. Damadian filed for and obtained a patent for scanning the human body with magnetic resonance imaging and formed his own company, FONAR. The first-ever MRI machine, dubbed "Indomitable," is now in the Smithsonian, and has taken its place alongside other notable "firsts" (Kelley 1).

Today, the MRI is considered an indispensable tool but acceptance of the technology did not come easily. Even after Dr. Damadian performed the first human body scan in 1977, his accomplishments was greeted with skepticism and dismissed by his peers.

Once the potential to detect cancerous tumors was accepted, however, Dr. Damidian had to fight off giant companies such as Hitachi and General Electric to protect his patented technology. Hitachi settled out of court, but the case against GE went to trail in 1995. In a "David vs. Goliath" lawsuit, FONAR won one of the largest patent settlements on record, $128.7 million (Kelley 2).

Basically, radio frequency energy is sent through the body of a patient, which is placed inside a strong magnet. The result is the patient's body will emit detectable signals containing information about the body's composition in response to the radio frequency energy source. Many of these signals must be collected in order to form a single MR image. Many cross-sectional images may be generated and they may be generated in any plane. The digital images may first be viewed on the operator's system console and then they can be printed on film (Femano 20).

MRI Technology has become a vital diagnostic tool, and Dr. Damadian believes that it will become an equally important tool for treatment. The initial technology has evolved, with the advent of "open" machines, the standing or weight bearing models, to an MRI operating room so the entire surgical team operates within it. (Kelley 2).

Medicine consists of essentially two parts: diagnosis and treatment. The diagnostic part of medicine has gone through a revolution in the last few decades, primarily because of the improvements in computer technology, which have culminated in magnetic resonance imaging. MRI has replaced very invasive and less diagnostic methods such as pneumoencephalography, myelography, and nuclear medicine brain scans. Due to its highly accurate diagnostic ability combined with its minimal risks and noninvasive nature, the use of MRI has skyrocketed. The term MRI has come into common usage even within the non-medical population. For example, over the course of a year, the sports section of most newspapers has numerous articles describing the MRI findings of local or national sports figures. MRI is able to diagnose neurological and musculoskeletal pathology earlier and more accurately than any other modality. MRI is beginning to approach the "tricorder" of Dr. McCoy in the popular television series Star Trek (Rothschild 3).

As use of MRI has proliferated, significant limitations have appeared: Claustrophobia and anxiety related reactions, restrictions on patient size and weight, and lack of access to the patient undergoing the examination have surfaced as problems facing traditional "tube-like" closed MRI scanners. However, most radiologists believed that only traditional closed MRI scanners held promise for the future. The simple descriptive term "open" caught on quickly with patients and referring doctors. Presently though, many of the same radiologists who previously shunned "open" technology have become converted, a fact reflected in the soaring popularity of open magnets. MRI technology has advanced at a whirlwind pace, allowing the once unthinkable to become reality. Improved computer hardware, software, gradients, and magnets have dramatically advanced the performance