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MRI

Magnetic resonance imaging (MRI) is a noninvasive method of using a magnetic field and radio waves to produce detailed images of the inside of the human body. Doctors use MRI to help diagnose medical conditions and disorders.

MRI is instrumental to detecting:

• central nervous system disorders
• brain and organ tumors
• brain abnormalities corresponding with dementia
• eye abnormalities
• reproductive system problems
• bladder problems
• blood vessel plaques and blockages
• bone and joint damage or infection
• breast cancer
• risk of stroke

Since the first magnetic resonance imaging machines were available in healthcare in the early 1980s, MRI has played a central role in the research, diagnosis, and maintenance of multiple sclerosis. Because the imaging uses magnetism and radio waves, it is safe for almost every person. As more machines are produced, the price decreases and the technology is more affordable to the public.

Since the 1980s, further advancements have been made in techniques used to help doctors and scientists understand the workings of MS inside the body. Some of the advancements in MRI include magnetic transfer MRI, diffusion-weighted MRI, proton MR spectroscopy, and functional MRI.

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MR Angiography

Magnetic resonance imaging (MRI) is a method of producing extremely detailed pictures of body tissues and organs without the need for x-rays. The electromagnetic energy that is released when exposing a patient to radiofrequency waves in a strong magnetic field is measured and analyzed by a computer, which forms two- or three-dimensional images that may be viewed on a TV monitor. MR angiography (MRA) is an MRI study of the blood vessels. It utilizes MRI technology to detect, diagnose and aid the treatment of heart disorders, stroke, and blood vessel diseases. MRA provides detailed images of blood vessels without using any contrast material, although a special form of contrast material is often given to make the MRI images even clearer. The procedure is painless, and the magnetic field is not known to cause tissue damage of any kind.

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Cardiac MRI

Magnetic resonance imaging is becoming very important in the initial diagnosis and subsequent management of coronary heart disease. MRI can help physicians to look closely at the structures and function of the heart and major vessels quickly and thoroughly, without the risks associated with traditional, more invasive procedures. Using MRI, physicians can examine the size and thickness of the chambers of the heart, and determine the extent of damage caused by a heart attack or progressive heart disease.

After a heart attack, for example, an MRI examination can help the cardiologist understand how well the heart is pumping, whether the flow of blood is blocked in any chamber or major vessel, whether the heart muscles are damaged or whether the lining of the heart is swelling. This is critical knowledge needed to administer prompt and effective treatment.

MRI can also detect the buildup of plaque and blockages in the blood vessels, making it an invaluable tool for detecting and evaluating coronary artery disease. Recently, specialists in MRI have demonstrated its potential for showing not only the structure, but also the function of the heart muscles, valves and vessels. Using MRI, they have created movie-like images of the beating heart that doctors can use to diagnose a variety of cardiovascular problems. More and more, MRI is being used as part of the traditional cardiac stress test to help physicians with earlier diagnosis and treatment of heart disease and to assess the patient’s recovery after treatment.

Magnetic resonance imaging (MRI) is a non-invasive way of viewing organs, soft tissues, bone and virtually all other internal body structures. MRI uses radio waves passed through a powerful magnetic field to produce clear and detailed pictures of the chest, providing information on the heart and lungs that cannot be otherwise obtained from an x-ray, ultrasound, or computed tomography (CT) scan.

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MRI of the Chest

Magnetic resonance imaging (MRI) is a non-invasive way of viewing organs, soft tissues, bone and virtually all other internal body structures. MRI uses radio waves passed through a powerful magnetic field to produce clear and detailed pictures of the chest, providing information on the heart and lungs that cannot be otherwise obtained from an x-ray, ultrasound, or computed tomography (CT) scan.

• Magnetic resonance imaging (MRI) of the chest gives very detailed pictures of the structures within the chest cavity, including the heart and lungs, from almost any angle.
• Abnormal growths, including cancer of the lungs or other tissues, may be detected and their size, extent, and degree of spread determined for staging purposes. MRI can often distinguish between tumors, other lesions, and normal tissues.
• MRI may reveal diseased heart valves at a stage when surgery may be easier and safer to perform.
• An MRI exam displays lymph nodes and blood vessels. It is a noninvasive method of showing whether blood flow is normal or reduced.
• A special form of MRI called magnetic resonance angiography (MRA) can demonstrate narrowing of the coronary arteries or an actual blockage by fatty deposits or a blood clot, which often precedes clinical heart disease. MRA may also demonstrate an abnormal ballooning out of the wall of an artery (aneurysm) or a torn inner lining of an artery (dissection).
• Disorders of the ribs and sternum may be assessed by chest MRI.
• An MRI exam can detect breast cancer at an early stage.
• MRI can provide visual guidance when doing an interventional procedure or taking a tissue sample (biopsy).
• MRI of the chest may clarify findings from a previous x-ray exam or computed tomography (CT) scan.
  

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MRI of the Head

MRI is the most sensitive exam for brain tumors, strokes, and certain chronic disorders of the nervous system such as multiple sclerosis. In addition, it is a useful means of documenting brain abnormalities in patients with dementia, and it is commonly used for patients with disease of the pituitary gland. MRI can detect tiny areas of tissue abnormality in patients with disease of the eyes or the inner ear.

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MRI of the Musculoskeletal System

The parts of the musculoskeletal system that are most frequently imaged with MRI are the spine, knee and shoulder. However, MRI has also been used to study almost every joint in the body, including the hips, wrists, and hands. MRI requires specialized equipment and expertise and allows evaluation of some body structures that may not be as visible with other imaging methods.

Because MRI can give such clear pictures of soft tissue structures near and around bones, it is usually the best choice for examination of the body's major joints, the spine for disk disease, and soft tissues of the extremities. MRI is widely used to diagnose sports-related injuries, as well as work-related disorders caused by repeated strain, vibration, or forceful impact.

Using MRI images, physicians can locate and identify the cause of pain, swelling or bleeding in the tissues in and around the joints and bones. The images allow the physician to clearly see even very small tears and injuries to tendons, ligaments and muscles, and even some fractures that cannot be seen on x-rays.

In addition, MRI images can give physicians a clear picture of degenerative disorders such as arthritis, deterioration of joint surfaces, or a herniated disk. Neurosurgeons often use MRI to evaluate the integrity of the spinal cord after trauma.

Finally, MRI is also useful for the diagnosis and characterization of infections (for example osteomyelitis) and tumors (for example metastases) involving bones and joints.

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MRI of the Spine

MRI has greatly improved the ability to visualize normal and diseased tissue in the spine (also called vertebral column or backbone), the bony structure that encloses the spinal cord. MRI frequently makes it possible to determine the cause of back pain. The examination shows the anatomy of the vertebrae that make up the spine, as well as the spinal cord and the spaces between the vertebrae through which nerves pass. MRI does require specialized equipment and expertise in order to perform it properly and correctly interpret the findings.

• Perhaps the most common reason for spinal MRI is to detect a bulging, degenerated, or herniated intervertebral disk—a frequent cause of severe lower back pain and sciatica.
• Compressed (or pinched) and inflamed nerves are visible on MRI. In some cases the cause of nerve compression, whether from a herniated disk, arthritis, or some other abnormality, also is indicated. MRI generally is the next non-invasive imaging examination used after x-rays of the lower spine.
• MRI is frequently done to help plan surgeries on the spine such as the decompression of a pinched nerve or spinal fusion. MRI performed after spinal surgery will show whether anything has changed and whether post-operative scarring or infection is present. If a patient has failed to improve as expected, MRI may show why.
• The exam can help to diagnose—or rule out—spinal infection or tumors that arise in, or have spread to, the spine; they include prostate, lung and breast cancers.
• When done before steroid is injected to relieve spinal pain, MRI can ensure that the medication will not be mistakenly injected into a tumor or site of infection.
• If your child has trouble with daytime wetting and does not fully empty the bladder, imaging the spinal cord may show why this is happening.
  

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MRI of the Prostate

The prostate is a walnut-size gland that is part of the male reproductive system. It is located below the bladder, where urine is stored, and surrounds the urethra, the tube that carries urine and other fluids out of the body. The prostate helps make the milky fluid called semen that carries sperm out of the body when a man ejaculates. Ultrasound and MRI are the most commonly used techniques to image the prostate gland.

The three most common prostate problems are:

• Infection (prostatitis)
• Enlarged prostate, called benign prostatic hyperplasia (BPH)
• Prostate cancer

The prostate tends to grow bigger with age due to the development of BPH. A tumor or infection can also enlarge the prostate. All of these conditions may squeeze the urethra, causing urinary problems.

Diagnosing a prostate problem may require a series of tests including an MRI exam, which can help identify abnormalities. If a biopsy has confirmed cancer, a doctor may use MRI or other imaging techniques to determine if the cancer is confined to the prostate, or if it has spread outside the walls of the prostate gland and elsewhere in the body.

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fMRI of the Brain

Functional magnetic resonance imaging (fMRI) is a relatively new procedure that uses MR imaging to measure the quick, tiny metabolic changes that take place in an active part of the brain. Physicians know the general areas of the brain where speech, sensation, memory, and other functions occur. However, the exact locations vary from individual to individual. Injuries and disease, such as stroke or brain tumor, can even cause functions to shift to other parts of the brain. fMRI not only helps radiologists look closely at the anatomy of the brain, but can help them determine precisely which part of the brain is handling critical functions such as thought, speech, movement, and sensation. This information can be critical to planning surgery, radiation therapy, treatment for stroke, or other interventions to treat brain disorders.

fMRI is becoming the diagnostic method of choice for learning how a normal, diseased or injured brain is working, as well as for assessing the potential risks of surgery or other invasive treatment of the brain. The term "Functional MRI" (with a "capital F") can also include other MRI techniques that are sensitive to physiologic changes (such as changes in water motion), whereas "little f" fMRI usually refers to mapping of brain activity using MRI. As a group, these "Functional MRI" techniques appear to provide the most sensitive method currently available for identifying, investigating, and monitoring brain tumors, strokes, and certain chronic disorders of the nervous system such as multiple sclerosis. In addition, these methods appear to provide a useful means of documenting some brain abnormalities related to dementia or seizures.

In routine practice, fMRI studies are often used in planning brain surgery, since they can help physicians monitor normal brain function as well as any disturbed brain function. While research is still ongoing, it appears that fMRI can also help assess the effects of stroke, trauma, or degenerative disease (such as Alzheimer's) on brain function.

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