MRI Study guide Questions and Answers 2023

MRI Study guide Questions and Answers 2023 MRI visible radiation reflects from the body 1. Visible light reflects off an object 2. reflected light detected by a that is sensitive to that kind of radiation - a RETINA MRI photograph is madeby 1. with reflex/refraction 2. electromagnetic radiation and receptors 3. visible lights extends from approximately 400 nm (blue) to 700 nm (red) x ray image radiation is transmitted through the body 1. electromagnetic radiation shines on a patient 2. some is absorbed 3.. some is transmitted through the patient to an image receptor 4. diagnostic images range from 20 kev to 150 kev RF Thomas Edison founded an electromagnetic radiation produced by the ossicular is called radiofrequency emission MR Image patient stimulated so electromagnetic radiation is emitted from the body...the emitted signal then detected, interpreted, and used to produce an image Magnetic resonance imaging are made with rf in the range from 10-200mhz (million) RF electromagnetic spectrum to produce images is based on a analytical procedure Nuclear Magnetic Resonance Imaging (NMRI) Word NUCLEAR dropped thought would become concern leaving with MRI 1819 Hans Christian Oersted Accidentally-discovered electricity produces magnetism Noted compass needle Reflects presence electric charge 1831 Michael Faraday 1. his gave us "Faraday's Law of Magnetic Induction 2. Bases of MR signal detection and precursor of modern day electro mechanics 3.He discovered: a That a magnetic field traversed through an electrical coil at a 90 degree angle would induce voltage (aka current) in the coil bIn order for it to be sustained the mag field (current) had to be interrupted by a pulse 1860 Sir James Clerk Maxwell 1. Discovered magnetic lines of force could be mathematically expressed 2. Some of his equations proved that electrical and magnetic fields coexist at 90 degrees to each other 3. Also noted, an induced magnetic field will spiral perpendicular to and in the opposite direction of the electron flow which produced it and at velocity of light (3x10 to the 6th meters per second) in a vacuum 3.Calculated velocity and propagation of electromagnetic waves and predicted existence 1868 Heinrich Hertz Discovered that invisible electromagnetic waves do exist and can be identified by their characteristic wave frequency value 1895 Wilhelm Konrad Roentgen Discovered high frequency electromagnetic X-rays 1896 Frederic Joliet & Marie Curie 1. Discovered gamma rays (waves) 2 All demonstrated that high frequency wave energies were: identifiable, detected, measurable, and often biologically damaged 1905 Albert Einstein: Law of Energy (E=mc²) Indicates mass and energy are one in the same 1911 Ernest Rutherford: Recognized the nucleus 1911 JJ Thompson: Electrons exist 1913 Niels Bohr Defined electron geometric patterns and properties/opened door to quantum physics Otto Stern: Method to measure magnetic dipole moment Wolfgang Pauli: Coined phrase Nuclear Magnetic Resonance Isidor Isac Rabi: Devised and performed nuclear magnetic resonance experiment 1946 Felix Bloch & Edward Purcell post ww2 Continued exploring the mystery of the atom 1. Ground work for utilizing sonography (submarine detection) and nuclear medicine (atomic energy) for human imaging Independently these two physicists noted: 2. Test tube sample of pure substance was magnetically energized and RF bombarded the excited atoms would respond by singing their own atomic "tune" 3. Tune signals were detected and recorded into spectroscopic values (corresponding to freq values) 4. Which is known as T1 and T2 relaxation rates 5 NMR the prelude to MRI was born 6. They were recipients of Nobel Prize in 1952 1970 Raymond Damadian MD Physician/physicist 1.NMR experiment on rats, surgically implanted malignant cells 2. Saw: tumor tissues respond to magnetic excitation and bombarded with pulse, would emit two different types of signals as relaxed back to equilibrium 3. Signals varied in image contrast characteristics Healthy/diseased...Bolch discovered and named earlier 4.Discovered water essence of MRI imaging 5.Proved could detect and record these signals returned 6..Like Roentgen 100 yrs before him, he envisioned the diagnostic value of these new magnetically induced rays 7. seven years spent designing and building the first whole body MRI scanner July 3, 1977 Raymond Damadian MD PERFORMED 1ST whole body transaxial PD slice required 4 h 45 min/patient had to come out106 times to accomplish NAMED IT: INDOMITABLE Now located at Smithsonian Institute of Technology in Washington DC 1973 Paul Lauterbur PhD 1. Further experimented with NMR principles 2. Sitting eating fast food, theorized that "superimposing controlled weaker magnetic field on top a stronger static mag field through the specimen, a specific region of the same freq value could be isolated and its signal detected and transformed into an image" 3. Much more research and experimentation, he was convinced: 4. Selected NMR signals could produce a magnetic tomographic region 5 Signals would be of sufficient magnitude for implementation of the principles of Fourier transformation (FT) 6. Magnets could possess sufficient magnetic homogeneity for selective image quality 7. 1973: designed and implemented use of three gradients (Gx, Gy, and Gz) for selective excitation imaging FDA approved contrast 1988 Components of the MR System •Nuclear alignment •Radio frequency excitation •Spatial encoding and Image formation The hardware utilized to achieve these processes or fundamental principles are: •Strong Magnet •Radio frequency source •Image Processor •Computer System why mri 1. Very detailed 3 dimensional images of organs and tissues throughout the body Using: 1.Very powerful magnetic (field) waves ly changing magnetic fields ter NO RADIATION patient is placed within the MR scanner Large tunnel or doughnut shaped "camera" •Loud •no pain •involves NO radiation •no known damages at this time How does an MRI work? 1. Magnetic field aligns atomic particles called PROTONS present in all of the body's tissues 2.Radio waves cause particles to produce signals picked up by receiver within scanner 3.Signals specially characterized using changing magnetic field, & computer-processor to create very sharp images of tissues as "slices" 3D projectiles 1. The powerful magnetic field of the MR system will attract iron-containing (also known as ferromagnetic) objects 2. May cause move suddenly & with great force 3. Can pose a possible risk to the patient or anyone in an object's flight path 4. Great care is taken to be certain that objects such as "ferromagnetic" objects are not brought into the MR system area MRI safety 2 1. It is vital remove any metallic belongings in advance of an MRI exam 2. The powerful magnetic field of the MR system will pull on any iron-containing object in the body, such as certain medication pumps or aneurysm clips 3. Every MRI facility has a protocol, when carefully followed, will ensure that the MRI technologist and radiologist know about presence of metallic implants/materials special precautions can be taken 1973 Lauterbur published paper describing technique for generating images using MR 1976 FDA give authority to regulate medical devices through Medical Device Amendments 1979 Experimental systems were capable of producing whole body images