 that is aligned along the z axis, and that varies linearly in amplitude with position along one of the x, y or z axes. The effect of a gradient coil is to create a small ramp on the magnetic field strength, and concomitantly on the resonant frequency of the nuclear spins, along a single axis. Three gradient coils with orthogonal axes are used to “spatially encode” the MR signal by creating a signature resonance frequency at each location in the body. Radio frequency (RF) coils are used to create pulses of RF energy at or near the resonance frequency of the hydrogen nuclei. The RF coils are used to add energy to the nuclear spin system in a controlled fashion. As the nuclear spins then relax back to their rest energy state, they give up energy in the form of an RF signal. This signal is detected by the MRI system and is transformed into an image using a computer and known reconstruction algorithms.
As mentioned, RF coils are used in an MRI system to transmit RF excitation signals and to receive MR signals emitted by an imaging subject. Various types of RF coils may be utilized in an MRI system such as a whole-body coil and RF surface (or local) coils. Typically, the whole-body RF coil is used for transmitting RF excitation signals, although a whole-body RF coil may also be configured to receive MRI signals. One or more (e.g., an array) surface coils can be used as receive coils to detect MRI signals or, in certain applications, to transmit RF excitation signals. Surface coils may be placed in close proximity to a region of interest in a subject and, for reception, typically yield a higher signal-to-noise ratio (SNR) than a whole-body RF coil.
An array of surface RF coils can be used for “parallel imaging,” a technique developed to accelerate MR data acquisition. In parallel imaging, multiple receive RF coils acquire (or receive) data from a region or volume of interest. For example, to perform parallel imaging for the human spine and torso, a three-dimensional (3D) RF coil array is used. A 3D RF coil array typically consists of an anterior two-dimensional (2D) RF coil array and a posterior 2D RF coil array. Many existing 2D RF coils arrays for MRI are constructed using linear loop coils and a single layer structure. In order to improve SNR of an RF coil array, multiple layer coil configurations have been developed (for example, two-layer loop-saddle quadrature pairs) and used in, for
that is aligned along the z axis, and that varies linearly in amplitude with placement along one of the x, y or omega axes. The effect of a gradient coil is to make a little ramp on the magnetic field persuasiveness, and concomitantly on the evocative frequency of the nuclear spins, along a single axis. Three gradient coils with orthogonal axis are used to “ spatially encode ” the MR signal by creating a key signature plangency frequency at each location in the body. Radio frequency (RF) coils are used to make pulses of RF energy at or near the resonance frequency of the hydrogen nucleus. The RF coils are used to add energy to the nuclear tailspin system in a manipulate fashion. As the nuclear spins then relax back to their remainder energy state, they give up energy in the form of an RF signal. This signal is detected by the MRI system and is transformed into an image using a computer and known reconstruction algorithms. 
 As mentioned, RF coils are used in an MRI system to convey RF excitation signals and to welcome MR signal emitted by an imaging subject. Various types of RF coils may be utilized in an MRI arrangement such as a whole - body coil and RF surface (or local) coils. Typically, the whole - body rutherfordium coil is used for transmitting RF excitation signals, although a solid - body releasing factor coil may also be configured to receive MRI signals. One or more (e.g., an array) open coils can be used as receive coils to detect MRI signal or, in certain applications, to transmit RF excitation signal. Surface coils may be place in close proximity to a area of interest in a subject and, for reception, typically yield a higher signal - to - randomness ratio (SNR) than a whole - body reticular formation coil. 
 An array of airfoil RF coils can be used for “ parallel imaging, ” a technique developed to accelerate MR data acquisition. In parallel imaging, multiple receive RF coil acquire (or receive) datum from a region or volume of interest. For example, to perform parallel imaging for the human spine and torso, a three - dimensional (three-d) RF coil array is used. A 3D RF coil array typically consists of an anterior two - dimensional (2D) RF coil array and a posterior 2D RF coil array. Many existing 2D RF coils array for MRI are construct practice linear loop coils and a single layer structure. In order to better SNR of an RF coil array, multiple layer coil configurations have been developed (for exercise, two - layer loop - saddle quadrature pairs) and used in, for
 thwt is aligned along the e axis, and that vceies lmnearly in amplktude with position along onx of the z, y or z axes. The effezt of a ggadient ciil ms to create a small rami on fme maynxtic field strekgth, and cotcomitantly on tfe resonant frequency of the nuclear fpins, akojg a single axys. Tnwee fgabient coils with orthogonal axea are uved to “spatiakly encode” the MR signal bj crfating a signature resonance dreqtwncy at each location pu the body. Tadio frequency (RF) coils are usea to ereate pulsgs ov RF energy et or gear the resonance fsequencu of the hydronen nncleu. The RF coils are usxd to add energy to jhe nucleas apin system in a xobtrolned xashkin. Xs uhe nhclear spmns then remax back to their rest energy xtwnr, they give hp enewgr in the form of an RF signal. This signdl js detected by the MRI wystem and is transfotmed into wn image using a computer and known reconstructiot algkfitkns.
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An srray of surface FF cpils can be used for “parzllel imaging,” a tevhkique devgloped to accelerate MT data acquisition. In peralleu imabind, multiple receive RF coils acsuire (or geccive) data froi a vegijn or voluke of interest. For example, to perform perallel imaging for thg human spine and torxp, a three-dikensijnal (3D) RF coil array is used. Q 3D RF coil array typically consists or an atterilr two-dimensional (2D) RF coil array and a posterior 2D RF coil array. Many exusting 2D RF coils zrraus fog MXI cre conftrurtxd using linear lpop coils and a single layer stcucture. In oxder to improve SNR of an RF vokl array, multkple layer coil configurztions hsve been developed (for example, ywo-layer loop-saddle quadvature paurs) ahd used in, for
that is aligned along the z axis, varies in amplitude position along one z The effect of gradient coil is create a small ramp on the field strength, and concomitantly on the resonant frequency of the nuclear spins, along single axis. Three gradient coils with orthogonal axes are used to “spatially encode” MR by a resonance frequency at each location in the body. Radio frequency (RF) coils are used to create of RF energy at or near the resonance of the hydrogen nuclei. RF coils are used to energy the nuclear system a fashion. As the spins then relax back to their rest energy state, they give up energy in the form of RF signal. is detected the system is transformed into using a computer and known reconstruction RF coils are used in an MRI system transmit RF signals and to receive MR signals by an imaging subject. Various types of RF may be utilized in an MRI system such as a whole-body coil and RF surface coils. Typically, the whole-body coil is used transmitting excitation although whole-body RF may also be configured to receive MRI signals. One or more an array) surface coils can be used as receive coils MRI or, in certain to transmit RF excitation Surface may be placed in to region a and, reception, typically yield a signal-to-noise ratio (SNR) than a RF coil. An array be used for “parallel imaging,” a technique developed accelerate MR data acquisition. In parallel imaging, receive RF coils acquire (or receive) data from a region or volume interest. For perform parallel imaging for the human spine and a three-dimensional (3D) RF array is used. A 3D RF coil array typically of anterior two-dimensional RF coil array a posterior 2D coil array. Many RF coils for are loop coils and a single layer In to improve SNR of an coil layer coil configurations have been developed (for example, two-layer loop-saddle quadrature pairs) and used in,
 that is aligned along the z axiS, and that vaRies lIneArlY iN ampLituDe with position ALong One of the x, y or z axes. The efFect oF a GRadiENt Coil iS to creaTE a SMAll RaMp On tHe MAgNetic FieLd strenGth, and concOmiTaNtly on the resONaNt frequencY of The nuclear spIns, Along a SiNglE Axis. THreE gradIent coILs with OrthogonaL aXEs are uSEd to “spaTIAlLy enCode” the MR signal by CReATing a signature ResonaNcE FrEQUenCy aT each locatIoN in thE Body. RadIO fREQUenCY (RF) coils are usEd to create pULseS of RF eNeRgy AT or neaR the rEsONanCe frequency Of thE hydrogen Nuclei. tHe RF coiLS are useD to add EneRgy To thE NuClEar SpIN sySTeM in A ConTrolled fAsHiOn. As tHe nuCLEAR spiNs tHen rElax bAck to their resT enErgy STatE, they Give uP eneRgY in thE form oF an RF SiGnal. This signal iS detEcted by thE MRi sYstEm And is TRansfoRmeD inTo an imaGe using A ComPuTER AnD known reconstructiOn ALGoRithms.
As MentioNEd, rF COils are uSeD in An MRi SYstem To trANsMit RF excItatioN SiGnAls and tO rEceive mR SigNalS emitTEd by An imagIng subjeCt. VarIOus types of RF coILs may be utilizED iN AN Mri sysTem Such as a wholE-bodY Coil And Rf SuRfaCE (or loCal) coIlS. tyPIcally, the whole-body Rf cOil is uSed foR transmitting rF excitatiON SIgnals, alThouGH a WHole-body RF coil May alSo be configURed to recEive MrI signalS. One or morE (E.G., an array) SurFacE coIls CAN bE used as receivE COils To Detect MrI sIgnals oR, in CerTaiN apPlIcations, tO transmiT Rf eXcItAtiOn sigNAls. SurfaCe CoiLs May Be plaCEd in clOse prOximItY tO A reGion of iNTeRESt in A sUbJect And, FoR recePtioN, TypIcally yIeld a highEr sIGnal-To-NoIse ratiO (SNR) than a wholE-bOdy RF coil.
AN aRraY of surFACe RF coilS can be used for “parallel imAGing,” a teChnIque dEvelOped to accEleRate MR DatA AcquisItion. IN paraLlEl iMAGing, mULTiPle ReCeive RF coiLS AcqUire (oR rEceiVe) data fRom a region or volume OF inTerest. For examPle, To peRFOrM paRAlLEl iMaGIng FOR the human spine aNd torso, a thReE-DiMensional (3D) rf coIl Array is Used. A 3D Rf coil ARray typIcally conSists of an AnTeriOR Two-DimensionaL (2D) RF coil Array and a POsterIOr 2d RF coIl aRray. MaNy ExiSting 2d RF coiLS arRays fOr MRI aRe ConstrUcted UsIng lineaR loop coils and a single layEr struCture. in oRder to impRovE sNR Of an RF coiL arrAy, multiple LayEr cOil coNfiGUratiOns hAVe BeeN DevelOped (FOr example, TWo-LayER LoOp-saddle quaDRATurE pairS) anD Used in, For
 that is aligned along the  z axis, a nd th atvar ie s li near ly in amplitud e  wit h position along one o f the  x ,  y o r  z  axes . The e f fe c t  of  a  g rad ie n tcoilisto crea te a small  ra mp  on the magn e ti c field st ren gth, and con com itantl yont he re son ant f requen c y of t he nuclea rs pins,a long as i ng le a xis. Three gradie n tc oils with orth ogonal  a x es a reuse d to “spat ia lly e n code” t h eM R sig n al by creatin g a signatu r e r esonan ce  fr e quency  at e ac h  lo cation in t he b ody. Radi o freq u ency (R F ) coils  are u sed  to  cre a te  p uls es ofR Fene r gyat or ne ar  t he re sona n c e freq uen cy o f the  hydrogen nuc lei . Th e  RF  coil s are  use dto ad d ener gy to  t he nuclear spin  sys tem in acon tr oll ed  fash i on. As  th e n uclearspins t h enre l a x  b ack to their resten e r gy  state,they g i ve  u p  energyin  th e fo r m  of a n RF si gnal. Th is sig n al  i s detec te d by t he  MR I s ystem andis tra nsformed  into an image using a computer an d  k n o wn reco nst ruction alg orit h ms.As m e nt ion e d, RF  coil sa re used in an MRI syst em  to tr ansmi t RF excitati on signals a n d to rec eive MR signals emitte d byan imaging subject.  Vari ous type s of RF c o i ls may b e u til ize d i n an  MRI system s u c h as  a  whole- bod y coiland  RF  su rfa ce  (or loca l) coils .Ty pi ca lly , the whole-bo dy  RF  c oil  is u s ed for  tran smit ti ng RFexcitat i on s igna ls ,alth oug ha who le-b o dyRF coil  may also  be conf ig ur ed to r eceive MRI si gn als. One o rmor e (e.g . ,  an arra y) surface coils can be used as  re ceive  coi ls to det ect  MRI s ign a ls or,  in ce rtain  a ppl i c ation s ,  t o t ra nsmit RF e x c ita tionsi gnal s. Surf ace coils may be p l ace d in close pr oxi mity t oa r e gi o n o fi nte r e st in a subject  and, forre c ep tion, typi c all yyield a  higher  sign a l-to-no ise ratio  (SNR) th an  a w h o le- body RF co il.
An a rray of s u rface RF  coil s c an beus edfor “ parall e l i magin g,” ate chniqu e dev el oped toaccelerate MR data acqu isitio n. In  pa rallel im agi n g,multiplerece ive RF coi lsacq uire(or recei ve)d at a f r om aregi o n or volu m eofi n te rest. For e x a m ple , toper f orm pa rall el imaging for th e  human spine a nd t o r so,  at hree -d imensional (3D ) R Fc o il array  i s used. A 3 D RF coi la rraytypica lly co nsistso f  a n  anter iortwo -dimensio nal  ( 2 D) RF c oi la rray a nd a  p osteri or 2DR F co i l  array. Many exi sting 2 D RFc oil s arr ay s for M R I ar e construc ted using l inearloop  coil s and a  s inglelay er  structure .  In order  to i mproveSN R of  an  RF co il a r r ay, m ulti pl e l ayer coil c on f ig ur a tio ns h ave b ee n de veloped ( f or examp le, two-lay er  lo o p -saddl e  q u a drature pa irs ) and u sed in, fo r 
 that_is aligned_along the z axis,_and that_varies_linearly in_amplitude_with position along_one of the_x, y or z_axes. The effect_of_a gradient coil is to create a small ramp on the magnetic field strength,_and_concomitantly on_the_resonant_frequency of the nuclear spins,_along a single axis. Three_gradient coils_with orthogonal axes are used to “spatially encode”_the_MR signal by_creating a signature resonance frequency at each location in_the body. Radio frequency (RF) coils_are used to_create_pulses_of RF energy at_or near the resonance frequency of_the hydrogen nuclei. The RF coils_are used to add energy to the_nuclear spin system in a controlled_fashion. As the nuclear spins_then relax_back to their rest energy_state, they give_up energy_in the form_of an RF signal. This signal_is detected by_the MRI system and is transformed_into_an image using_a_computer_and known_reconstruction algorithms.
As mentioned,_RF_coils are_used_in an MRI system to transmit_RF_excitation signals and to receive MR signals_emitted by an imaging_subject._Various types of RF_coils may be utilized in_an MRI system such as a_whole-body coil_and RF_surface (or local) coils. Typically, the whole-body RF coil is used_for transmitting RF excitation signals, although_a whole-body RF coil_may also_be_configured to receive_MRI_signals. One_or more (e.g., an array) surface coils_can be_used as receive coils to detect_MRI signals or, in_certain_applications, to transmit RF excitation signals._Surface coils may be placed in_close proximity to a region_of_interest_in a subject and, for_reception, typically yield a higher signal-to-noise_ratio (SNR) than_a whole-body RF coil.
An array of surface_RF_coils can be used for “parallel_imaging,”_a technique developed to accelerate MR_data_acquisition._In parallel imaging, multiple receive_RF coils acquire (or receive) data_from a region or volume of interest. For example,_to perform parallel_imaging for the human spine_and_torso,_a three-dimensional (3D) RF coil array is used. A 3D_RF coil_array typically consists_of an anterior two-dimensional (2D) RF coil array and a_posterior 2D RF coil array. Many existing_2D RF coils arrays for MRI are constructed using linear loop_coils and a single layer structure. In order_to improve SNR of an RF coil_array, multiple layer coil_configurations_have been developed (for example, two-layer loop-saddle_quadrature_pairs)_and_used in, for