MRI Scan

New MRI scan technology

Since the very first generation of MRI scanners, we have come a long ways. In the last decade, a newer generation of scanners have been developed which have revolutionized he way we practice medicine. For the novice, there are subtle differences in the MRI scanners available but for the best images one should be aware that the magnetic strength of the scanner is important.

Magnetic strength: the strength of the magnet is very important, and the higher the strength the better the mages. The high-field scanners (1.5 Tesla magnets) are generally regarded as the latest MRI available today. The lower field scanners with lower magnetic strength (0.25-0.5 tesla) are not adequate for great detail and also take a lot longer to perform

The older MRI scanners are basically an enclosed tunnel in which a patient has to lie still for 30-45 minutes. Some patients who may have difficulty with a traditional MRI scan include:

Claustrophobia. A few patients are claustrophobic and cannot tolerate the confined space within the tunnel. The vast majority of these individuals will be sufficiently relaxed with sedatives taken orally. All 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, the latest MRI scanners are now available which cater to correct the above deficits. Because the traditional tunnel scanners may not work well for some people, the latest in MRI offers the following:

Short bore 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. While some patients may find the more open MRI scanners easier to tolerate, the machines use a lower-field magnet and do not generate as good an image. With a lower quality image. It is often difficult 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 and decreasing the feeling of claustrophobia.

Advantages of MRI over CT scan

has no radiation exposure
offers 3 dimensional, Image in any plane
uses Non Iodinated contrast agent
any large blood vessel can be evaluated with or without use of contrast
is excellent to visualize bone disorders
offers greater small structure detail
is the best for evaluating soft tissues
Complements CT

MRI imaging has revolutionized the diagnosis and treatment of numerous disorders. MRI technology is constantly improving, although at great financial costs to the end consumers (doctors and their patients). The newest and usually most expensive equipment tends to be available in most 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.

MRI Screening Procedures

Breast

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 benefit for some women such as:

With a high risk of breast cancer, especially those under age 40
Women who are known to have BRCA-1 or BRCA-2 mutations
A personal history of breast cancer
A history of carcinoma in situ or atypical hyperplasia, which may evolve into breast cancer
Dense breast tissue that's difficult to assess with mammography

Mammography continues to offer benefit to all women because of its superiority in identifying micro calcifications associated with breast cancer.