Magnetic resonance imaging: history, types, principles, and clinical applications

Magnetic Resonance Imaging

History of MRI

The Magnetic Resonance Imaging (MRI) was first tested in Budapest Hungry in 1882. Later in 1937, Professor Isidor Rabi of Columbia University assembled a Nuclear Magnetic Resonance. This tool was effective because it could absorb and emit radio waves after exposure to a strong magnetic field. Professor Carr Herman produced one-dimensional MRI imaging processor in 1952. The nuclear powered NMR was instrumental in experiments developed to detect the presence of tumors in normal cells. However, the technology was fully adopted in 1973 when Lauterbur Paul successfully produced the first NMR image (Lauterbur, 1973). Previously, Damadian created the NMR imaging machine in 1972, but not until 1973 did Lauterbur apply it for imaging. Following the success, Peter Mansfield developed an arithmetical methodology that was vital in integrating the concept to real-time problems.

Before the emergence of this concept, magnetic scans took hours to process. However, Mansfield Scans took seconds and could carry out several scans (Webb, 2009, p. 449). As of 1980, MRI was extensively used to detect various tumors: Mallard John applied the MRI scanner to detect primary and secondary tumors. Bottomley Paul is accredited as the pioneer of the modernized MRI. His efforts led to the improvement of the 1.5T system, which could detect tumors in the heart and brain. This technology was important in developing high sensitivity and resolution performed at up 9.4T (Vaughan, DelaBarre & Snyder, 2006).

Types of magnets used

Cambridge University Press (2007) establishes four main types of MR magnet courtesy of Air-cored resistive magnet, iron-cored electromagnets, permanent magnets, and superconducting magnets (p. 169). Initially, Air-cored resistive magnets were predominantly used in MRI projects. However, Iron-Cored Electro magnets replaced this technology. The primary reason for abandoning this technology was its bulkiness and slowness. The Iron-Cored Electro magnets applied electronically powered soft-iron pole pieces. Essentially, an electric current is used to power coils, thereby building magnetic fields around the coils. However, this technology lost relevance because it could not create sufficient magnetic power. This led to the development of permanent magnets. The magnets are induced during manufacture and could only create a magnetic field of (0.2 -- 0.3 T). The superconducting magnets were a hybrid of magnetically induced irons with electric harbored fields. An electric current was achieved when a loop was super conducted by a wire within a given temperature range.

Principles of MRI

For industrial control, MRI technology was developed to achieve a directional magnetic field. This was structured on nuclei containing an odd number of neutrons and protons with motions or precession. Recently, MRI technology received a sufficient boost with the integration of computer-aided imaging system like 2D or 3D display. This graphic orientation is later scaled on relaxation time, T1, and Transverse time, T2 in a simple XY axis platform (Rumsey, & Ernst, 2009, p. 417). The basic principles seek to achieve the best angles for visibility. A human body produces naturally induced magnetic fields its nuclei react in Larmor precession projects angular frequencies. The graphical presentation is projected on x, y and z method head-to-toe. Modern computers facilitate the processes with 3D preferences.

Comparison of MRI & conventional radiography

Conventional radiography is a parallel technology that uses an imaging plate. The plate is staged in a special apparatus with a specialized body part scheduled for examination; the X-ray is conducted on this platform. The image generated from the X-ray is viewed and can be altered with software designed for such function. In a close comparison between the two technologies, it is clear that MRI is a superior technology because of its ability to communicate with atoms that trigger various body physiological functions. Conventional radiography image is static and cannot be viewed in superior 3D versions compared to dynamic images generated by MRI technology. MRI uses body electricity to determine the medical condition of the subject. MRI is a safe technology unlike conventional radiography that uses X-ray energy to generate digital images. Besides, MRI has a higher ability to test several medical conditions compared to conventional radiography. This is based on the knowledge that MRI is essentially empowered to communicate with body atoms and not a reflection of body tissues.

Safety of MRI

The word 'nuclear' was dropped because of its negative connotation in matters related to safety. MRI technology is a safe technology and does not use ionizing radiation. In addition, clinical setups exclude special cases like pregnant from carrying an MRI diagnosis. This is because MRI technology controls atoms in a managed environment. In the end, it is easy to carry out a complex atom study in a managed environment. It has not been proven whether the fetus can be biologically affected by the magnetic fields in case the processes are installed conditionally in the mother's body. For safety, medical procedures have exempted the use of MRI in cases like pregnancies (Joyce, 2008). Besides, it is not advisable to use close to materials emitting magnetic fields like phone Sim-cards and credit cards.

Clinical application