The effects of paramagnetic contrast agents on metabolite protons in aqueous solution.
The longitudinal (R1) and transverse (R2) relaxivities of the clinically used contrast agents Gd(DTPA)2-, Gd(DOTA)- and Gd(DTPA-BMA) have been determined in mixed aqueous metabolite solutions for choline, creatine and N-acetylaspartate. Measurements were performed at 1.5 T using a STEAM sequence on 25 mM metabolite solutions at pH = 7.4 and 22 degrees C. The data showed that for all the contrast agents and metabolites, R1 approximately = R2. The largest range of relaxivity values was found for Gd(DTPA)2-, where R2 = 6.8 +/- 0.3 mM(-1) s(-1) for choline and 1.5 +/- 0.4 mM(-1) s(-1) for N-acetylaspartate. Variation in relaxivity values was attributed primarily to differences between the charges of the paramagnetic agent and metabolite. The maximum potential influence of the contrast agents on in vivo metabolite signals was calculated using the measured relaxivities.
Murphy
Philip S
PS
CRC Clinical MR Research Group, The Institute of Cancer Research and The Royal Marsden NHS Trust, Sutton, Surrey, UK.
Leach
Martin O
MO
Rowland
Ian J
IJ
D002794:Choline / Q000378:metabolism; D003198:Computer Simulation; D003287:Contrast Media / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019786:Gadolinium DTPA / Q000494:pharmacology; D006571:Heterocyclic Compounds / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009942:Organometallic Compounds / Q000494:pharmacology; D011522:Protons; D013997:Time Factors; D014867:Water / Q000378:metabolism
D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; D011522:Protons; D014867:Water; C064925:gadodiamide; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate; D019786:Gadolinium DTPA; D002794:Choline