21/03/2015 MRIscanHowitworksNHSChoices
http://www.nhs.uk/Conditions/MRIscan/Pages/Howdoesitwork.aspx
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Yourhealth,yourchoicesMRIscanHowitworks
HowanMRIscanworksDuringamagneticresonanceimaging(MRI)scan,youlieinastrongmagneticfieldandradiofrequencywavesaredirectedatyourbody.Thisproducesdetailedimagesoftheinsideofyourbody.
Mostofthehumanbodyismadeupofwatermolecules,whichconsistofhydrogenandoxygenatoms.Atthecentreofeachhydrogenatomthereisanevensmallerparticlecalledaproton.Protonsareliketinymagnetsandareverysensitivetomagneticfields.
Whenyoulieunderthepowerfulscannermagnets,theprotonsinyourbodylineupinthesamedirection,inthesamewaythatamagnetcanpulltheneedleofacompass.
Shortburstsofradiowavesarethensenttocertainareasofthebody,knockingtheprotonsoutofalignment.Whentheradiowavesareturnedoff,theprotonsrealignandindoingsosendoutradiosignals,whicharepickedupbyreceivers.
Thesesignalsprovideinformationabouttheexactlocationoftheprotonsinthebody.Theyalsohelptodistinguishbetweenthevarioustypesoftissueinthebody,becausetheprotonsindifferenttypesoftissuerealignatdifferentspeedsandproducedistinctsignals.
Inthesamewaythatmillionsofpixelsonacomputerscreencancreatecomplexpictures,thesignalsfromthemillionsofprotonsinthebodyarecombinedtocreateadetailedimageoftheinsideofthebody.
Pagelastreviewed:05/09/2013
Nextreviewdue:05/09/2015
