New MRI scan technology
MRI scanning technology has progressed significantly in recent years. In the last decade, a newer generation of scanners has been developed which produce excellent-quality images, allowing physicians more opportunities to treat and diagnose patients in a less-invasive, highly accurate manner.
Magnetic strength: the strength of the magnet is a key element to MRI scanning. The stronger the magnet, the better the image quality will be. The high-field scanners (1.5 Tesla magnets) are generally regarded as the most modern MRI magnet available today. The lower field scanners with lower magnetic strength (0.25-0.5 tesla) are not able to provide images with great detail and scans with this strength of magnet take longer to perform.
Traditional MRI scanners look like an enclosed tunnel in which a patient has to lie still for 30-45 minutes while the scan is performed. Some patients may have difficulty undergoing these scans due to factors such as:
- Claustrophobia. Some patients are claustrophobic and have difficulty tolerating the confined space within the tunnel. Often, oral sedation can help alleviate the anxiety these patients feel. There are other options available, but the highest resolution MRI scanners are completed tunnels and tend to accentuate the claustrophobic reaction.
- Size. The MRI scanner is a confined space, and some obese patients may be too large to fit in the MRI scanner tunnel. Some MRI scanners also have weight limits.
- Pain. If a patient has back or joint pain, lying still for a prolonged period may not be well tolerated.
However, due to varying needs of patients, new MRI scanners are now available that can address some of the above concerns. Because the traditional tunnel scanners may not work well for some people, the latest in MRI offers the following:
Short bore magnets: Magnets have been developed that combine the accuracy of a tunnel scanner and the comfort of an open MRI scan. Although they are not completely open, they are much less constrictive because of the short bore magnet (shorter tunnels), but can produce a high-field with excellent imaging.
Open MRI: Open scanners have been developed to avoid the claustrophobic effect so common with the older scanners. These scanning machines are designed to allow the patient to lay on their back while a large disk hovers above them. The machine remains open on either side of the patient. While some patients may find the more open MRI scanners easier to tolerate, the machines use a lower-field magnet and do not generate quite as accurate of an image when compared to traditional MRI scanning machines. This can be a concern because with a lower quality image it is often difficult for physicians to make a definitive anatomic diagnosis.
Shorter tunnels: Most modern, high-field magnets are now designed with Short Bore Tunnels and, theoretically, maintain the highest image quality while causing less claustrophobia and are more easily tolerated by patients who are unable to lie still for a prolonged time. The high-field units (1.5 Tesla or greater) obtain images much faster, thus decreasing patient discomfort if laying still for a long period of time is difficult. Since less time is required, claustrophobic patients are better able to tolerate the scanning process, as well.
Stand-Up MRI: The Stand-Up MRI is a recently developed machine that allows more flexibility in the scanning process. The Stand-Up MRI machine is designed to allow patients to be scanned in a variety of positions, including standing, sitting, or bending over; none of which are possible using traditional MRI scanners. Dynamic positioning allows physicians to examine images of the body under normal weight bearing conditions, so symptoms that are felt only when bending or standing can be evaluated in a more accurate way. Another major advantage of the Stand-Up MRI is that the machine is open on the top and in the front, reducing the feeling of claustrophobia that some experience. The design of the Stand-Up MRI scanner also can accommodate individuals of above average weight, allowing people of most body types to receive the benefits of MRI technology.
Advantages of MRI over CT scan
There are significant advantages associated with MRI scanning compared to CT scans. MRI scans:
- Involve no radiation exposure
- Offer a 3-dimensional image in any plane
- Use non-iodinated contrast agent
- Can evaluate any large blood vessel with or without the use of contrast
- Provide excellent visualization of bone disorders
- Offer greater small-structure detail
- Are the best for evaluating soft tissues
- can complement the use of CT scans
MRI imaging has revolutionized the diagnosis and treatment of numerous disorders. MRI technology is constantly improving, although because new machines can be costly, the newest equipment is usually available in hospitals.
In many communities there is no choice in the scanner to be used, but where there is a choice it is advisable to get the best quality scan the first time - especially if a patient is considering surgery. MRI scans have taken a considerable amount of guesswork out of medicine as they can give very accurate anatomic detail that can be used to plan a surgical approach, identify a potential problem, track the progress of treatment, or accurately diagnose a condition.
MRI Screening Procedures
MRI screening for breast cancer is not recommended for everyone. There is no evidence that it offers results superior to mammography in older women with an average risk of breast cancer. MRI appears to offer significant benefits for women who:
- Have a high risk of breast cancer, especially those under age 40
- Are known to have BRCA-1 or BRCA-2 mutations
- Have a personal history of breast cancer
- Have a history of carcinoma in situ or atypical hyperplasia, which may evolve into breast cancer
- Tend to have dense breast tissue that is difficult to assess with mammography
Mammography continues to offer benefits to all women because of its superiority in identifying micro-calcifications associated with breast cancer.
Uses of MRI
- Angiography Head (MRA) to assess blockage of vessels in the head
- Temporal Mandibular Joint to assess jaw and neck pain
- Internal Auditory Canals (Ear) to assess for causes of deafness
- Pituitary Gland/Sella to assess masses causing hormonal disturbance
- Head Contrast to assess strokes
- Head without contrast to assess injury to brain and causes of dementia
- Eye to assess cause of visual problems
- Angiography Neck (MRA) to assess blockage of vessels in neck
- Soft Tissue Neck to assess masses in the neck
- Thyroid to assess masses in the neck
- Cervical Spine without contrast to assess cause of neck pain
- Cervical Spine with contrast to assess degenerative disease of spine
- Brachial Plexus to assess areas of compression of the nerves
- Breast Biopsy to help localize and biopsy mass
- Breast to assess breast for any masses
- Thoracic Spine without contrast to assess causes of back pain
- Thoracic Spine with contrast to assess degenerative disease of spine
Upper Extremities Scans
- Shoulder to assess cause of pain, tendon rupture
- Hand/Wrist to assess joints and nerves
- Elbow/Forearm to assess joint and bones
- Abdomen to assess presence of infection, masses, blood vessels
- Kidneys to assess masses, infection and inflammation
- GI Tract (Enteroclysis) to detect ulcers, tumors or infection
- MRCP to detect problems with biliary system
- Lumbar Spine without contrast to detect causes of back pain
- Lumbar Spine with contrast to detect degenerative causes of spine
- Pelvis-Female Anatomy to assess female pelvic pathology
- Pelvis-Male Anatomy to assess male pelvic pathology
Lower Extremities Scans
- Foot to assess tendon, ligament, cartilage, fractures, tumors
- Calf to assess presence of blood clot, masses, infection
- Thigh to assess presence of blood clot, masses, infection
- Knee to assess joint, cartilage, infection, inflammation
- Ankle to assess joint, cartilage, infection, inflammation
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By ScanDirectory.com Staff
Updated: August 1, 2007