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Magnetic Resonance Imaging (MRI)

MRI Introduction

History of MRI

Working independently, Felix Bloch of Stanford University and Edward Purcell of Harvard University made the first successful nuclear magnetic resonance experiment to study chemical compounds in 1946. Dr Bloch and Dr Purcell were awarded the Nobel Prize for Physics in 1952. In the early 1980s, the first "human" magnetic resonance imaging (MRI) scanners became available, producing images of the inside of the body. Current MRI scanners produce highly detailed 2-dimensional and 3-dimensional images of the human anatomy.

Introduction

An MRI is similar to a computerized topography (CT) scanner in that it produces cross-sectional images of the body. Looking at images of the body in cross section can be compared to looking at the inside of a loaf of bread by slicing it. Unlike a CT scan, MRI does not use x-rays. Instead, it uses a strong magnetic field and radio waves to produce very clear and detailed computerized images of the inside of the body. MRI is commonly used to examine the brain, spine, joints, abdomen, and pelvis. A special kind of MRI exam, called magnetic resonance angiography (MRA), examines the blood vessels.
An MRI of the brain produces very detailed pictures of the brain and is commonly used to study people with such problems as headaches, seizures, weakness, hearing loss, and blurry vision. It can also be used to further evaluate an abnormality seen on a CT scan. During a brain MRI, a special device called a head coil is placed around the person's head to help produce very detailed pictures of the brain. The head coil does not touch the person, and the person can see through large gaps in the coil.
Spine MRI is most commonly used to look for a herniated disk or narrowing of the spinal canal (spinal stenosis) in people with neck, arm, back, and/or leg pain. It is also the best test to use to look for a recurrent disk herniation in a person with a history of prior back surgery.
Bone and joint MRI can be used to check virtually all of the bones, joints, and soft tissues. MRI can be used to identify injured tendons, ligaments, muscles, cartilage, and bones. It can also be used to look for infections and masses.
MRI of the abdomen is most frequently used to look more specifically at an abnormality seen on another test, such as an ultrasound or a CT scan. The exam is usually tailored to look at just the liver, pancreas, or adrenal glands.
For women, pelvic MRI provides a detailed look at the ovaries and uterus and is often used to follow up an abnormality seen on ultrasound. It is also used to evaluate the spread of cancer of the uterus. For men, pelvic MRI is sometimes used to check those diagnosed with prostate cancer. Pelvic MRI is also used to look at the bones and muscles of the pelvis.
Magnetic resonance angiography (MRA) depicts the blood vessels. The blood vessels in the neck (carotid and vertebral arteries) and brain are frequently studied by MRA to look for areas of constriction (narrowing) or dilatation (widening). In the abdomen, the arteries supplying blood to the kidneys are also frequently examined using this technique.