Introduction
Magnetic resonance imaging (MRI) is referred to as a test that makes use of the magnetic field as well as the radio waves in order to produce the pictures of organs of the body. It also produces the structures of the of the body (Pettersson 1998). It has been found out that MRI normally produces pictures of the organ of the body in a very different manner. However, it differs with some techniques such as X-ray, ultrasound or computed tomography. MRI again can produce some problems which might otherwise not be found using other techniques already mentioned. Image quality of MRI scanner is influenced by an increase in the static magnetic field strength. Therefore, this paper shall seek to demonstrate how Larmor equation’s increase in precessional frequency as a result of an increase in static magnetic field strength impacts the image quality of 3T and 1.5T scanners.
Discussion
In order to do the MRI test, the part of the body which is supposed to be studied must be placed inside a special machine which must contain strong magnetic field (Pettersson 1998). The greatest benefit of MRI is that its pictures are digital and for future studies they can be stored in a computer. Remote review of the images produced by MRI can also been done while in either the clinic or the court room. In order to increase the clarity of the image produced by MRI, contrast material may be used. There are several reasons why Magnetic Resonance Imaging (MRI) can be done. It can be used to find problems such as tumors, infection, blood vessel diseases, bleeding and several internal injuries (Berquist 2012). MRI can give a finer detail about the images produced by some other imaging techniques such as X-ray and ultrasound scan.
The Larmor equation talks about the precession of magnetic moments of the atoms, atomic nuclei, and electrons. This takes place on the external magnetic field. Torque is being exerted the magnetic field on the magnetic moment (Louis N. Hand and Janet D. Finch 1998).
The above formula shows Larmor precession equation where shows the torque, the magnetic dipole is being represented by, the angular momentum vector is shown by and represents the external magnetic field. The symbol shows the gyromagnetic ration. This ratio gives the proportionality constant which exists between the angular momentum and the magnetic moment (Lee 2006).
Magnetic moments tend to align with the field when placed with in the magnetic field. At times; the magnetic moment can be seen as the magnetic loop (Teng 2012). Furthermore, the alignment can be termed as torque on the current loop which is being exerted by the magnetic field. The fact that the magnetic moment being seen as the magnetic loop can be put into use by while describing the moments in orbital electrons, electron spins and nuclear spins. Here the magnetic moment in question is associated with angular momentum. Torque tends to align the magnetic moment with the magnetic field (Yousem and Grossman 2010). While talking about nuclear case, the angular momentum is the intrinsic one. A magnetic moment directed towards the magnetic field, it will produce a torque on the magnetic field. This is what is causing precision about the magnetic field direction.
Magnetic Resonance Imaging (MRI) as the name appears uses magnetic field and also radio wave to give the image of the body. The only difference which occurs between MRI and the x-ray type of imaging is that the former does use iodized radiation to produce images. MRI technology is mostly used in hospitals to perform diagnose (Levitt 2013).
3Tesla magnetic resonance imaging (3T MRI) has got higher field strength as opposed to 1.5T. Here, signal to noise ratio is increased as well as spatial resolution and speed. The above factors my give some substantial benefits to the scanner. According to Larmor, the elongation of 3T gives image contrast which is improved. The magnetic resonance sequence in angiography is greatly improved due to the saturation of the tissue at the background and also the improved CNR provides improved image contrast.While comparing the consequence at 3T and 1.5T, the consequences of the former is similar, but have got greater magnitude than that 1.5T. The trace which is referred to as the electcardiogram becomes none-diagnostic because of the presence of T-wave which is artificially elevated. However the vectorcardigram is used to solve the problem of triggering (Hand and Finch 1998).
The Larmor equation also explains that the safety of the scanner relies on the strength of the magnetic field. Actually, three forces are involved here, a force known as translation force which acts exactly on ferromagnetic objects that are brought closer to the scanner. The torque is on the patient and finally the forces of moving charges within the patients’ body. The reason why the 3T scanner becomes more popular is that it can even be tested at higher field strength (Hand and Finch 1998).
The two scanners are being differentiated by their image clarity. The 3T scanner seems to be clearer than 1.5T (Levitt 2013). During the frequency encoding, the MRI scanners uses frequency which is precessional. This is to indicate spatial position in the direction of frequency encoding.it is known that when protons are exposed to changing magnetic fields, their precession frequency changes as well (Hendrick 2007). This is termed as chemical shift. Protons which are found in organs and muscle moves or rather resonate at different frequency than those found in lipids (Lee 2006). The MRI scanner will interpret frequency in lipids and in other organs in each and every different way. The Larmor equation explains that frequency shifts approximately at the rate of 3.5 parts-per-million (ppm).
The technology of magnetic resonance will continue to give challenges even with the evolution of 3T MRI and other technologies which considered advanced (Berquist 2012). The challenges which are brought about by 3T images should be understood very well in order to improve on the spatial resolution, the speed and very consistent image quality when it compared with the presently used 1.5T MRI system (Teng 2012). The next is the emergence of coil design, a technique which is known as SAR as well as the pulse sequence. There is also the development of advanced MR procedures for 3T. Those advancements involve functional neuroimaging together with high resolution musculoskeletal. As the clinical gold standard, 3T is believed to have overtaken 1.5T as a tool used in diagnostics environment. In the radiology community, the MRI will continue to evolve and become better (Pettersson 1998).
Conclusion
In conclusion, it is evident from the information explicated above that 3T MRI has a greater field strength compared to 1.5T. This is attributed to the fact that 3T elongation as a result of the Larmor equation gives it an improved image contrast. Consequently, the 3T MRI scanners produce clearer images compared to 1.5T MRI scanners. Despite these differences, the MRI scanners interpret frequency in lipids and in other organs in different ways. The Larmor equation explains that frequency shifts approximately at the rate of 3.5 parts-per-million (ppm). This further explicates the concept that Larmor equation clarifies that the safety of an MRI scanner relies on the strength of its magnetic field.
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