The MRI scanners - Essay Example

The MRI scanners A cross sectional image of the human anatomical structures is produced by using radio waves and the scan thus obtained is called an MRI scan, and the more the magnetic strength is power, the clearer the image quality would be. Magnets have widespread use, in and out of medicine. With the MRI scanners how having a 3T magnet, it means that that particular magnet scanning your body is sixty thousand times as powerful as the earth’s magnetic field. The new MRI scanner is going to change the way doctors make medical diagonesis. The new scanner is designed to create a new kind of imagining called a fMRI, this type of scan uses a noninvasive technique to produce images that have such a high resolution that even a single millimeter of an area of the brain could be distinguished. This is very important during the procedures in which surgery is required to treat tumors and epilepsy for instance) that can effect brain tissue near cerebrum or the areas that control movement, the newer versions of the scanner have contributed to developing additional magnetic resonance technology. MRA or Magnetic resonance angiography is a test that is used to evaluate blood flow through the arteries without cutting it open to see. MRA is also used to detect aneurysms within the brain and abnormalities of the blood capillaries in the brain, spinal cord or in the other systems of the body. Magnetic resonance spectroscopy (MRS) is another noninvasive procedure done by using MRI scanners is to assess chemical abnormalities in the tissue such as the brain. It is can be used to diagnose diseases such as HIV-AIDS, infections of the brain, stroke, Alzheimer's disease, tumors, and multiple sclerosis. To determine the specific location is a brain where a certain function such as memory or cognitive development occurs functional magnetic resonance imaging is used this is useful because even though the human brain is the same in every human but the exact location of some general areas may vary, during this scan the patient might be asked to perform a specific task such as talk so the fMRI can detect the exact location of the place of the brain and the surgeons can go and perform surgery in that specific area increasing the chances of success of the surgery. Micro structures in the human body such as small blood capillaries which cannot be seen otherwise could now be seen with this high field MRI technique, drilling down to the micro level.3 Tesla MRI scanner now have the ability and capacity to perform the functions of a workhose 1.5 tesla scanner, and do it with much more speed. In the body, the SNR (Signal to noise ratio) of the coils of both the scanners is almost same. Apart from the some of the modification in the doses of contrast system, both the scanners have the same user interface in the clinical systems. New 3- tesla has user interface and parameters as 1.5 tesla scanners. both the scanners i.e. 1.5 & 3 Tesla give the same T2 ,weighting image quality; the redesigning of the pulse sequence has made the 3 Tesla scanner more efficient however the MRI angiographs have been very mush same with both the scanners . This image quality is better with 3-tesla, since engineers have overcome the problems of the SAR, specific absorption rate. The challenge with 3-tesla is that with the increased radio frequency exposure to the human tissue, you might have to face physiologic limitation that would restrict the speed at which you could scan the 3-T scanners improve spatial resolution and apply imaging techniques that would otherwise would not be possible since it would require the patient to be in the 1.5 T scanner for too long. since there is no need to fight motion any more neuroimages with the help of the extra signal in 3T they can increase resolution to get more defining cognitive mapping of the human tissue conduct high resolution inflow MR angiography and enhance the quality of the diffusion studies. Since the person getting an MRI scan has to hold their breath, the need for speed is vital which the 3T has provided the luxury to perform with faster speed."You can go twice as fast as 1.5T with the same types of signal to noise, or you can get twice as much resolution, or you can go with a combination of the two," (Karen 2011) Nuclear spin refers to the total angular momentum of a nucleus by the symbol I. for the electrons in the atoms, there is a difference between electron spin and electron orbital angular momentum and then combines them to give the total angular movement. with each nuclear spin, there is a nuclear magnetic field effect which then produces magnetic interactions with its environment. Protons have magnetic properties which are known as nuclear spin. They are tiny magnetics in the orbit of the nucleus which are represented by vectors. When all the tiny magnetic field of each spin comes together they form net magnetization. The sum of all the spins give a null net magnetization. External magnetic field known as B0 nuclear spins have to align themselves to the external field parallel or some align themselves anti parallel. In the MRI- 3 tesla hydrogen is widely used to image nuclei since it is found in great abundance in the human tissue. Other nuclei have a net nuclear spin, for example 19F, 13 C, 31 P, 23 Na also have nuclear spins that can be used in MRI but since they not so widely found in the human tissue, and require an RF chain tuned to their resonance frequency it is not used. The unit of the MRI scans is Tesla, which is used to access the amount of strength the magnetic field has to penetrate the human body. The 3 T MRI is vital for health care providers in identifying disorders of the musculoskeletal system and also the sensitive organs, where it might not be easy to do an invasive surgery. The 3T MRI is expected to change the way brain disorders are diagnosed, in order to get to the brain surgeons generally need to cut through the cranial cavity. With a more powerful magnetic field, a closeup magnification of the brain can be taken with the scanner. Another advantage for the patients requiring Magnetic Resonance Imaging isthat it requires shorter time being in the machine which one is more comfortable for the patient, two for people suffering from claustrophobia is easier and less time is required to hold the breath while in the scanner. The only drawback of this new technology might be for pregnant patients. The radio waves from the magnetic which is used to get an image of the required anatomical region of the body non-invasively, maybe cause some physical damage to the fetus. Phyicisians usually try not to order an MRI in pregnant women in 1.5 T but eventually if all 1.5T will be replaced by 3 T it might mean more exposure to more powerful magnetic waves which could cause more damage. When a comparison study is done between a 3 tesla and a 1.5 tesla the results are obvious, enabled with better signal to noise ratio the 3 T reflects a more finer and sharper picture as compared to the dull and coarser view of the internal human body that 1.5 T scanner depicts. The more detailed and visible the anatomical structures are under the 3T scanner beats the spatial resolution of 1.5 T scanners. When the two scanners are compared for imagine in the thalamus (a part of the brain) the 3T shows more clearly defined dark spots than the 1.5 suggesting an increase in susceptibility. For liver scans a comparison was done to find out inceased B1 inhomogenity, and in the 3 Tesla scanner the fat suppressed area was more well defined as opposed to a blurry image in the 1.5 MRI scanner. The uses of 3 Tesla magnetic resonace imaging scanners have now started to be used in clinical trails to assit complex studies of the organ disorders. The advantages are widespread, increased chemical shift, more signal to noise ration means the MRI scans will be more clearer to read and intercept for the radiologists. However, some disadvantages are increased relaxation time. References Sandrick, Karen. "Advanced MR Special Supplement: 3–tesla MRI bests 1.5–tesla in body and brain." diagnostic imaging. N.p., n.d. Web. 23 May 2012. . Read More