Frequency dependence of MR relaxation times. I. Paramagnetic ions.
T1 and T2 of paramagnetic ions in free and chelated form were measured over the range of clinical magnetic resonance imaging field strengths (0.02-1.5 T). T1 values agreed with published data; however, to our knowledge, the field dependence of T2 has not been systematically studied before Mn2+, Cr3+, and Fe3+ all showed T2 reduction at high field strengths, although reduction due to Fe3+ was minimal. This is believed to be due to "contact" interactions, which have been previously noted for manganese. No such T2 reduction was seen in the chelates, except that dysprosium chelate (but not free ion) showed an anomalous decrease in T2 at high field strengths, which may possibly be explained by a dephasing effect caused by the large magnetic moment of Dy3+.
Vymazal
J
J
Neuroimaging Branch, NINDS, National Institutes of Health, Bethesda, MD 20892.
Bulte
J W
JW
Frank
J A
JA
Di Chiro
G
G
Brooks
R A
RA
D002857:Chromium; D003287:Contrast Media; D003300:Copper; D004419:Dysprosium; D004492:Edetic Acid; D005290:Ferric Compounds; D005682:Gadolinium; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging; D008345:Manganese; D009942:Organometallic Compounds; D004369:Pentetic Acid
D003287:Contrast Media; D005290:Ferric Compounds; D009942:Organometallic Compounds; D002857:Chromium; C041365:gadolinium EDTA; D004419:Dysprosium; D008345:Manganese; D003300:Copper; D004369:Pentetic Acid; D004492:Edetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA; C019179:Fe(III)-EDTA