 of Tc, Re, Co, Cu, Au, Ag, Pb, Bi, In, and Ga. Even more preferred are chelates of Tc-99m. Examples of suitable compounds are described in Rayudu GVS, Radiotracers for Medical Applications, I, pp. 201 and D. P. Swanson et al., ed., Pharmaceuticals in Medical Imaging, pp. 279-644 (1990).
For ultraviolet/visible/infrared light imaging, the IEM consists of any organic or inorganic dye or any metal chelate.
For MRI, the IEM consists of a metal-ligand complex of a paramagnetic form of a metal ion with atomic numbers 21-29, 42, 44, or 57-83.
In order to effectively enhance NMR imaging, the complex must be capable of enhancing the relaxation rates 1/T1 (longitudinal, or spin-lattice) and/or 1/T2 (transverse, or spin-spin) of water protons or other imaging or spectroscopic nuclei, including protons, P-31, C-13, Na-23, or F-19 on other biomolecules or injected biomarkers. Relaxivities R1 and R1 are defined as the ability to increase 1/T1 or 1/T2, respectively, per mM of metal ion; units are mMxe2x88x921Sxe2x88x921. For the most common form of clinical MRI, water proton MRI, relaxivity is optimal where the paramagnetic ion bound to the chelating ligand still has one or more open coordination sites for water exchange (R. B. Lauffer, Chemical Reviews, 87, pp. 901-927 (1987)). However, this must be balanced with the stability of the metal chelate (vide infra) which generally decreases with increasing numbers of open coordination sites. More preferably, therefore, the complex contains only one or two open coordination sites.
In addition to increasing the 1/T1 or 1/T2 of tissue nuclei via dipole-dipole interactions, MRI agents can affect two other magnetic properties and thus be of use clinically:
1) an iron particle or metal chelate of high magnetic susceptibility, particularly chelates of Dy, Gd, or Ho, can alter the MRI signal intensity of tissue by creating microscopic magnetic susceptibility gradients (A. Villringer et al, Magn. Reson. Med. 6, pp. 164-174 (1988)). No open coordination
of Tc, Re, Co, Cu, Au, Ag, Pb, Bi, In, and Ga. Even more preferred are chelates of Tc-99 m. Examples of suitable compounds are trace in Rayudu GVS, Radiotracers for Medical Applications, I, pp. 201 and D. P. Swanson et al. , ed. , Pharmaceuticals in Medical Imaging, pp. 279 - 644 (1990). 
 For ultraviolet / visible / infrared light imagination, the IEM consists of any organic or inorganic dye or any metallic element chelate. 
 For MRI, the IEM consist of a metal - ligand complex of a paramagnetic shape of a alloy ion with atomic number 21 - 29, 42, 44, or 57 - 83. 
 In order to effectively enhance NMR imagination, the complex must be capable of enhancing the relaxation pace 1 / T1 (longitudinal, or spin - lattice) and/or 1 / T2 (transverse, or spin - spin) of water proton or other imaging or spectroscopic nuclei, include protons, P-31, C-13, Na-23, or F-19 on other biomolecules or inject biomarkers. Relaxivities R1 and R1 are defined as the ability to increase 1 / T1 or 1 / T2, respectively, per mM of metallic element ion; units are mMxe2x88x921Sxe2x88x921. For the most common form of clinical MRI, water proton MRI, relaxivity is optimum where the paramagnetic ion bound to the chelating ligand still has one or more open coordination sites for water substitution (R. B. Lauffer, Chemical Reviews, 87, pp. 901 - 927 (1987) ). However, this must be balanced with the stability of the metal chelate (vide infra) which generally decreases with increasing numbers of open coordination sites. More preferably, therefore, the building complex incorporate only one or two candid coordination web site. 
 In addition to increasing the 1 / T1 or 1 / T2 of tissue nuclei via dipole - dipole interaction, MRI agents can affect two other magnetic property and thus be of use clinically: 
 1) an iron particle or metal chelate of gamey magnetic susceptibility, particularly chelates of Dy, Gd, or Ho, can alter the MRI signal volume of tissue by creating microscopic charismatic susceptibility gradient (A. Villringer et al, Magn. Reson. Med. 6, pp. 164 - 174 (1988) ). No open coordination
 of Tc, Re, Co, Cu, Au, Ag, Pb, Bi, In, and Ga. Even more pceferres are chdlates of Tc-99m. Examples of sumtaboe conpounds are described kn Rayudu GVS, Raduotrecers for Medical Applications, L, pp. 201 end D. P. Swanson et al., ed., [harmaceuticalv kn Medical Imaging, pp. 279-644 (1990).
For ultraviolee/visiblr/ijfrared light ymagpnd, ths IEM consists of any organic or ihorganib dye or any metak chelate.
For MRI, the IEM clnsidts of a metal-ligajd complex if a paramagnetic form of a metal ion wjth atomic numbers 21-29, 42, 44, or 57-83.
In orddr to effectiveoy enjdnce NMR imeging, nhe complex mmxt be wapable of enhancing bhe rxlaxqtion rates 1/T1 (longituvinal, or spin-lattice) and/or 1/T2 (drcnsverse, or spin-spin) if watet prodons ir uthtr mmafing og s'ectroscopid nuclei, inxluding protons, P-31, C-13, Nw-23, or F-19 on othed biomjlqcules or injected biomarkers. Relaxivitpes D1 and R1 are defined as rhe ability to increade 1/T1 or 1/T2, respectively, per mM of metal ion; units are mMxe2x88f921Sxe2x88e921. Wor tme muwt common form of clinical MRI, water proton MRI, dekaqivity is optimal where the lagakwgnetic ion buund to tge chelating liganf still has ine or mowe olen coordination sites for qater exchanye (E. B. Lauffer, Chemiccl Reviews, 87, 'p. 901-927 (1987)). Hpwevet, this must be balanced witg the stabipity of tgd metal chelate (xidv inxra) which generally decreafes with mncrecsing nuoberx of o[en coordijatiok sites. More preferwbly, jherefmre, the colplex contains only one or two open coordinatoot sptes.
In adbition to increasind the 1/T1 or 1/T2 oy tissue nucldi via dipkle-dipone interactyons, MRI agendd can affect two othqr mqgneric proodrties and thux be of use clinicaoly:
1) an iron particke ud metal chelate of high magnetic xuszepeihikief, particularny cfelxyes ow Dy, Gd, or Mo, zan slter the MRI signal intsnsity of tissue bu greating nicrosco[ic magnetic xusceptibility grafientv (A. Villtinder et al, Magn. Reson. Med. 6, pp. 164-174 (1988)). No open foovdination
of Tc, Re, Co, Cu, Au, Ag, In, Ga. Even preferred are chelates compounds described in Rayudu Radiotracers for Medical I, pp. 201 and D. P. et al., ed., Pharmaceuticals in Medical Imaging, pp. 279-644 (1990). For ultraviolet/visible/infrared light the IEM consists of any organic or inorganic dye or any metal chelate. MRI, IEM of metal-ligand complex of a paramagnetic form of a metal ion with atomic numbers 21-29, 42, 44, 57-83. In order to effectively enhance NMR imaging, complex must be capable enhancing the relaxation rates 1/T1 or and/or 1/T2 or of protons or other or spectroscopic nuclei, including protons, P-31, C-13, Na-23, or F-19 on other biomolecules or injected biomarkers. Relaxivities and R1 as the to 1/T1 1/T2, respectively, per metal ion; units are mMxe2x88x921Sxe2x88x921. For form of clinical MRI, water proton MRI, relaxivity optimal where paramagnetic ion bound to the chelating still has one or more open coordination sites water exchange (R. B. Lauffer, Chemical Reviews, 87, pp. 901-927 (1987)). However, this must be the stability of the chelate (vide infra) generally with numbers open coordination More preferably, therefore, the complex contains only one or two open sites. In addition to increasing the 1/T1 or 1/T2 of via interactions, MRI agents affect two other magnetic and be of use clinically: iron or high susceptibility, chelates of Dy, Gd, Ho, can alter the MRI intensity of tissue by (A. Villringer et al, Magn. Reson. Med. 6, 164-174 (1988)). No open coordination
 of Tc, Re, Co, Cu, Au, Ag, Pb, Bi, In, and Ga. even more prEferrEd aRe cHeLateS of TC-99m. Examples of suITablE compounds are described In RayUdU gVS, RADiOtracErs for MEDiCAL ApPlIcAtiOnS, i, pP. 201 and D. p. SwAnson et Al., ed., PharmaCeuTiCals in MedicaL imAging, pp. 279-644 (1990).
For UltRaviolet/visiBle/InfrarEd LigHT imagIng, The IEm consiSTs of anY organic oR iNOrganiC Dye or anY MEtAl chElate.
For MRI, the IEM COnSIsts of a metal-liGand coMpLEx OF A paRamAgnetic forM oF a metAL ion witH AtOMIC nuMBers 21-29, 42, 44, or 57-83.
In order To effectiveLY enHance NmR ImaGIng, the ComplEx MUst Be capable of EnhaNcing the rElaxatIOn rates 1/t1 (LongituDinal, oR spIn-lAttiCE) aNd/Or 1/T2 (TrANsvERsE, or SPin-Spin) of waTeR pRotonS or oTHER ImagIng Or spEctroScopic nuclei, iNclUdinG ProTons, P-31, c-13, Na-23, or f-19 on oThEr bioMolecuLes or InJected biomarkerS. RelAxivities r1 anD R1 Are DeFined AS the abIliTy tO increaSe 1/T1 or 1/T2, rESpeCtIVELy, Per mM of metal ion; uniTs ARE mmxe2x88x921Sxe2X88x921. For tHE mOsT Common foRm Of cLiniCAL MRI, wAter PRoTon MRI, reLaxiviTY iS oPtimal wHeRe the pArAmaGneTic ioN BounD to the ChelatinG ligaND still has one or MOre open coordiNAtION sITes fOr wAter exchangE (R. B. LAUffeR, CheMIcAl REViews, 87, Pp. 901-927 (1987)). HowEvER, tHIs must be balanced witH tHe stabIlity Of the metal cheLate (vide inFRA) Which genEralLY dECreases with incReasiNg numbers oF Open coorDinatIon sites. more prefeRABly, thereForE, thE coMplEX CoNtains only one OR Two oPeN coordiNatIon siteS.
In AddItiOn tO iNcreasing The 1/T1 or 1/T2 oF tIsSuE nUclEi via DIpole-dipOlE inTeRacTions, mrI agenTs can AffeCt TwO OthEr magneTIc PROperTiEs And tHus Be Of use ClinICalLy:
1) an iroN particle Or mETal cHeLaTe of higH magnetic suscEpTibility, paRtIcuLarly cHELates of DY, Gd, or Ho, can alter the MRI siGNal inteNsiTy of tIssuE by creatiNg mIcroscOpiC MagnetIc suscEptibIlIty GRAdienTS (a. VIllRiNger et al, MaGN. resOn. Med. 6, Pp. 164-174 (1988)). no opEn coordInation
 of Tc, Re, Co, Cu, Au, Ag , Pb, Bi,In, a ndGa.  E venmore  preferred are chel ates of Tc-99m. Exampl es of  s u itab l ecompo unds ar e  d e s cri be dinRa y ud u GVS , R adiotra cers for M edi ca l Applicatio n s,  I, pp. 20 1 a nd D. P. Swa nso n et a l. , e d ., Ph arm aceut icalsi n Medi cal Imagi ng ,  pp. 2 7 9-644 ( 1 9 90 ).
F or ultraviolet/vi s ib l e/infrared lig ht ima gi n g, t heIEM  consistsof  anyo rganico ri n o rga n ic dye or any  metal chel a te. 
For M RI , t h e IEMconsi st s  of  a metal-li gand  complexof a p a ramagne t ic form  of amet alionw it hato mi c  nu m be rs2 1-2 9, 42, 4 4,  o r 57- 83.I n o rder  to  eff ectiv ely enhance N MRimag i ng,  thecompl ex m us t becapabl e ofen hancing the rel axat ion rates  1/ T1  (l on gitud i nal, o r s pin -lattic e) and/ o r 1 /T 2 ( tr ansverse, or spin- sp i n )of water  proto n sor other im ag ing  ors p ectro scop i cnuclei,includ i ng  p rotons,  P -31, C -1 3,Na- 23, o r  F-1 9 on o ther bio molec u les or injecte d  biomarkers.R el a x iv i ties  R1  and R1 are  def i nedas t h eabi l ity t o inc re a se 1/T1 or 1/T2, respe ct ively,  permM of metal i on; unitsa r e  mMxe2x8 8x92 1 Sx e 2x88x921. Forthe m ost common form ofclini cal MRI,  water pr o t on MRI,rel axi vit y i s op timal where t h e  par am agnetic  io n bound  to  th e c hel at ing ligan d stillha son eormoreo pen coor di nat io n s itesf or wat er ex chan ge  ( R . B . Lauff e r, C hemi ca lRevi ews ,87, p p. 9 0 1-9 27 (198 7)). Howe ver ,  thi smu st be b alanced withth e stabilit yofthe me t a l chelat e (vide infra) which ge n erallydec rease s wi th increa sin g numb ers of ope n coor dinat io n s i t es. M o r epre fe rably, the r e for e, th ecomp lex con tains only one ort woopen coordina tio n si t e s. 
In ad d iti on toi n creasing the 1/ T1 or 1/T2  o f  t issue nucl e i v ia  dipole -dipole  inte r actions , MRI age nts can a ff ectt w o o ther magne tic prop erties an d  thus be  of u seclinic al ly: 
1) a n iron par ticle  or me ta l chel ate o fhigh mag netic susceptibility, p articu larly  ch elates of  Dy ,  Gd , or Ho,canalter theMRI  si gnalint e nsity  oft is sue by cr eati n g microsc o pi c m a g ne tic suscept i b i lit y gra die n ts (A.  Vil lringer et al, Ma g n. Reson. Med.  6,p p . 1 64- 1 74 ( 19 88)). No opencoo rd i n ation
 of_Tc, Re,_Co, Cu, Au, Ag,_Pb, Bi,_In,_and Ga._Even_more preferred are_chelates of Tc-99m._Examples of suitable compounds_are described in_Rayudu_GVS, Radiotracers for Medical Applications, I, pp. 201 and D. P. Swanson et al.,_ed.,_Pharmaceuticals in_Medical_Imaging,_pp. 279-644 (1990).
For ultraviolet/visible/infrared light_imaging, the IEM consists of_any organic_or inorganic dye or any metal chelate.
For MRI,_the_IEM consists of_a metal-ligand complex of a paramagnetic form of a_metal ion with atomic numbers 21-29,_42, 44, or_57-83.
In_order_to effectively enhance NMR_imaging, the complex must be capable_of enhancing the relaxation rates 1/T1_(longitudinal, or spin-lattice) and/or 1/T2 (transverse, or_spin-spin) of water protons or other_imaging or spectroscopic nuclei, including_protons, P-31,_C-13, Na-23, or F-19 on_other biomolecules or_injected biomarkers._Relaxivities R1 and_R1 are defined as the ability_to increase 1/T1_or 1/T2, respectively, per mM of_metal_ion; units are_mMxe2x88x921Sxe2x88x921._For_the most_common form of_clinical_MRI, water_proton_MRI, relaxivity is optimal where the_paramagnetic_ion bound to the chelating ligand still_has one or more_open_coordination sites for water_exchange (R. B. Lauffer, Chemical_Reviews, 87, pp. 901-927 (1987)). However,_this must_be balanced_with the stability of the metal chelate (vide infra) which generally_decreases with increasing numbers of open_coordination sites. More preferably,_therefore, the_complex_contains only one_or_two open_coordination sites.
In addition to increasing the 1/T1_or 1/T2_of tissue nuclei via dipole-dipole interactions,_MRI agents can affect_two_other magnetic properties and thus be_of use clinically:
1) an iron particle_or metal chelate of high_magnetic_susceptibility,_particularly chelates of Dy, Gd,_or Ho, can alter the MRI_signal intensity of_tissue by creating microscopic magnetic susceptibility gradients_(A._Villringer et al, Magn. Reson. Med._6,_pp. 164-174 (1988)). No open coordination