1. Magnetic Resonance Imaging Huafen Guo

2. Introduction Medical Imaging Part of Biomedical imaging Radiology X-ray radiography ultrasound endoscopy magnetic resonance imaging etc. Musculoskeletal: joint disease and soft tissue tumors Neuroimaging : neurological cancer Functional MRI: brain Etc.

3. Components

4. Procedure Three field involved:  Static magnetic field (very strong one)  gradient field  Radio-frequency (RF) field. MR signal: protons spin around their own axes

5. Procedure  Excitation: it obtain information from the spins, powerful radio transmitter to generate the electromagnetic field to excite the spins.  Return to equilibrium: RF frequency transmitter-----switch off.  Spatial encoding :MR signal from the proton contain the information about where those protons are positioned in the patient ------create the image (three steps) slice selection frequency encoding phase encoding.

6. Slice Selection  Add magnetic gradient  vertical slice: the direction of gradients altered to an anterior-posterior gradient.

7. Disadvantage  exposure of RF field----implanted devices  implant (level of safety)  MR-Safe, completely nonmagnetic, non-electrically conductive, and non-RF reactive.  MR-Conditional, may contain magnetic, electrically conductive or RF-reactive.  MR-Unsafe: contain magnetic electrically conductive or RF-reactive.  projectile effect accidents  acoustic noise---- ear protection  Uncomfortable  older scanner :40 minutes  now:20 minutes

8. Conclusion  Better improvement in the future.

9. Question?

10. Reference  M. Lakrimi1, A.M. Thomas, G. Hutton, M. Kruip, R. Slade, P. Davis, A.J.Johnstone, M.J. Longfield, H. Blakes, S. Calvert, M. Smith, C.A. Marshall.(2011). The principles and evolution of magnetic resonance imaging. Journalof Physics: Conference Series, Volume286,Number1.http://iopscience.iop.org/article/10.1088/17 426596/286/1/012016;jsessionid=3BCB7EFDD1F401DB3AF8A4CB59 C0B48B.c6.iopscience.cld.iop.org#artAbst  Robert-Jan M. van Geuns, Piotr A. Wielopolski, Hein G. de Bruin, Benno J.Rensing, Peter M.A. van Ooijen, Marc Hulshoff,Matthijs Oudkerk, and Pim J.de Feyter. (1999). Basic principles of magnetic resonance imaging. Volume 42,Issue 2,Pages 149–156. Retrievedfromhttp://www.sciencedirect.com.uri.idm.oclc.org/sci ence/article/pii/S0033062099700149  Domenico F. Sergio S. (2004). Biological effects of exposure to magneticresonance imaging: an Overview.Vol.3,p.11- 11Retrievedfromhttp://web.b.ebscohost.com.uri.idm.oclc.org/eh ost/pdfviewer/pdfviewer?vid=1&sid=77e1ac2c-6bd2-4c35- 869ffebbeaa21608%40sessionmgr115&hid=129  Wikipedia.(2015). Medical imaging. Retrieved fromhttps://en.wikipedia.org/wiki/Medical_imaging  Wikipedia.(2015). Magnetic resonance imaging. Retrieved from https://en.wikipedia.org/wiki/Magnetic_resonance_imaging