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MRI Machine Guide
- 1. Magnetic Resonance Imaging By: Lillian Xue and Stephanie Ganzeveld Date: 10/30/13
- 2. MRI Machine Various shapes of MRI machines Closed MRI The traditional closed MRI machine is cylindershaped and possesses movable bed slides which patients rest on in order to enter the inner magnetic tube. The difference between closed MRI machines and open MRI machines Open MRI The open MRI machine is ring-shaped (instead of cylinder-shaped) and encloses only the region of the body under inspection. Upright MRI The upright MRI machine allows patients to either sit or stand inside of the relatively open vertical scanner. Upright MRI machine
- 3. Practical Uses Diagnosis of brain tumors Identification of hemorrhage Recognition of abnormal brain development Discernment of lesions connected with multiple sclerosis Diagnosis of hormonal instability Possible locations for malignant brain tumors Abnormal brain development in young children Identification of hemorrhage
- 4. Method To begin, MRI machines focus primarily on the nuclei of hydrogen atoms in polar water molecules. Hydrogen protons, under normal circumstances, spin arbitrarily with their “axises” pointing in various directions. When the body is placed under a magnetic current (as issued by the MRI Machine), all of the protons line up to face in the same direction. The alignment of positive subatomic particles creates a magnetic vector which is consequently identified by the MRI scanner. Protons of Hydrogen spinning in arbitrary directions Radio waves are then added in concurrence with the magnetic current to deflect the original magnetic vector. When the radio waves are turned off, the magnetic vector returns to its initial state, causing another radio wave signal to be produced. This signal is what MRI machines translate to produce accurate scans. Protons of Hydrogen spinning in the same direction
- 5. Method Continued Receiver coils are placed around the part of the body being inspected to improve signal emission How long it takes protons to return to their resting state can be evaluated in two ways: Time taken for the magnetic vector to return to its initial state (T1 relaxation) Time needed for the axial spin to return to its resting state (T2 relaxation) Receiver coils in MRI machines In essence, MRI scans are composed of a series of pulse patterns. Since different tissues have different relaxation states they can thus be distinguished from one another. In this respect, diseases can be identified by increased water content. T1 and T2 relaxation
- 6. Advantages of MRI Does not involve x- or exposure to radiation and is not invasive. Provides clear images of soft tissue structures such as grey matter. Provides images of the brain at any direction, or slice. Provides information on the blood moving through areas of the body. The difference between white and grey matter Various brain slice angles
- 7. Disadvantages of MRI Can be very expensive and unaffordable Can be dangerous for patients with metallic devices placed within the body such as pacemakers Performed in small spaces which will be difficult to be performed on claustrophobic patients Movement during scanning may cause blurry images, so the patient must lie still during the scan. RF transmitters can cause severe burns if misused or mishandled. Claustrophobia as a result of closed MRI machines Pacemakers and other metallic devices are not permitted RF (radio frequency) power should be used with caution
- 8. Advantages of fMRI non-invasive and effective no exposure to radiation, unlike CT, X-Rays, and PET scans high resolution images (1mm) signals can be recorded from all regions in the brain, unlike EEG scans more precise than PET scans Example of functional MRI scans High resolution images fMRI scans are able to show the brain from all regions
- 9. Disadvantages of fMRI can only examine the blood flow in the brain (cannot detect activities of neurons) results may be difficult to interpret (cannot specify emotions or feelings) Unfortunately, fMRI scans can only examine blood flow in the brain Results may be difficult to interpret or analuze
- 10. Difference between MRI and fMRI Magnetic Resonance Imaging (MRI) views anatomical structure focuses on protons in hydrogen nuclei high, spatial resolution utilized for experimental purposes MRI scan Functional Magnetic Resonance Imaging (fMRI) views metabolic function calculates oxygen levels long-distance resolution utilized for diagnostic purposes fMRI scan
- 11. Maguire and MRI Used fMRI to locate blood flow in the brain "FMRI can tell you which brain areas are involved in memory but you are never sure which ones are really necessary. That is where the study of patients comes in." Used to see which areas were active when participants were trying to locate a specific region from spatial memory The hippocampus was not the only active region of the brain Used MRI to compare the structures of the brain Hippocampus Hippocampus as shown on the fMRI scan Identification of spatial navigation
- 12. References (Sources) Tilakaratna, P. (n.d.). Magnetic Resonance Imaging : Basic principles of how it works. Retrieved November 4, 2013 from http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html Berger, A. (January, 2002). Magnetic Resonance Imaging. Retrieved November 2, 2013 from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1121941/#!po=16.6667 Blake, L. (2013). What does MRI equipment look like? Retrieved November 4, 2013 from: http://www.ehow.com/facts_5499464_mri-equipment-look-like.html Smith, A. (2013). Reasons for an MRI of the brain. Retrieved November 4, 2013 from: http://www.ehow.com/facts_5499464_mri-equipment-look-like.html Kalapurayil, M. (2013, July). What is MRI? How does MRI work? Retrieved November 4, 2013 from: http://www.medicalnewstoday.com/articles/146309.php Seven Counties Services Inc. (n.d.). Functional Magnetic Resonance Imaging. Retrieved November 4, 2013 from http://www.sevencounties.org/poc/view_doc.php?type=doc&id=8947&cn=18 CancerQuest (2011, October). Benefits and Disadvantages of MRI. Retrieved November 4, 2013, from http://www.cancerquest.org/mri-advantages-and-disadvantages.html Schwartz., A. (n.d.). MRI: Advantages and Disadvantages. MRI: Advantages and Disadvantages. Retrieved November 4, 2013, from http://www.anapolschwartz.com/practices/gadolinium-nsf/blog/mri-side-effects.html Health information you can trust. (n.d.). MRI scan. Retrieved November 4, 2013, from http://www.nhsinform.com/health-library/articles/m/mri-scan/advantages Chudler, E. (2013). Brain imaging. Retrieved November 4, 2013 from: http://faculty.washington.edu/chudler/image.html