Evaluation of polyaza macrocylic methylene phosphonate chelates of Gd3+ ions as MRI contrast agents

C. F G C Geraldes, R. D. Brown, W. P. Cacheris, S. H. Koenig, A. D. Sherry, M. Spiller

Research output: Contribution to journalArticle

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Abstract

Gd(DTPA)2- (diethylenetriaminepentaacetic acid) and the polyaza macrocyclic Gd(DOTA)- (1,4,7,10-tetraazacyclododecane-N,N',N'',N''') are paradigms of general purpose paramagnetic complexes useful for enhancing contrast in magnetic resonance imaging (MRI). It is of both fundamental and practical interest to determine how one might modify the chemical structure of these chelate complexes to improve their utility for MRI in specific circumstances. In the present work, we investigated polyaza methylene phosphonate complexes of Gd3+ ions to compare their NMRD profiles with those of their carboxylate analogs and with Gd(DTPA)2-. We find that the number q of exchangeable water molecules coordinated directly to the Gd3+ ions tends to be smaller in the phosphonates, in principle reducing their utility in MRI. However, these phosphonates have a tendency to oligomerize, and the resulting decrease in rotational mobility of the paramagnetic oligomers increases their relaxivity at higher fields, offsetting the effect of decreases in q. In particular, Gd(DOTRP)3- (1,5,9-triazacyclododecane-N,N',N'',-tris(methylenephosphonic acid)) would be an increasingly effective contrast agent above ~ 10MHz if the oligomerization was stable in vivo (and the Gd3+ ions were sufficiently well bound). At lower fields, the relaxivity of these small chelate complexes is dominated by τ(S0), the relaxation time of the spin moments of the paramagnetic ions. We find this to be favorably long for complexes of Gd3+ with the macrocyclic phosphonate ligands, as was found earlier by us for Gd(DOTA)-. This situation, ostensibly related to the relatively high symmetry and rigidity of the macrocyclic complexes, can increase the low-field relaxivity of the phosphonates almost a factor of 2 beyond that of Gd(DTPA)2-.

Original languageEnglish (US)
Pages (from-to)94-104
Number of pages11
JournalMagnetic Resonance in Medicine
Volume9
Issue number1
StatePublished - 1989

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Organophosphonates
Contrast Media
Gadolinium DTPA
Magnetic Resonance Imaging
Ions
Acids
Ligands
Water

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

Geraldes, C. F. G. C., Brown, R. D., Cacheris, W. P., Koenig, S. H., Sherry, A. D., & Spiller, M. (1989). Evaluation of polyaza macrocylic methylene phosphonate chelates of Gd3+ ions as MRI contrast agents. Magnetic Resonance in Medicine, 9(1), 94-104.

Evaluation of polyaza macrocylic methylene phosphonate chelates of Gd3+ ions as MRI contrast agents. / Geraldes, C. F G C; Brown, R. D.; Cacheris, W. P.; Koenig, S. H.; Sherry, A. D.; Spiller, M.

In: Magnetic Resonance in Medicine, Vol. 9, No. 1, 1989, p. 94-104.

Research output: Contribution to journalArticle

Geraldes, CFGC, Brown, RD, Cacheris, WP, Koenig, SH, Sherry, AD & Spiller, M 1989, 'Evaluation of polyaza macrocylic methylene phosphonate chelates of Gd3+ ions as MRI contrast agents', Magnetic Resonance in Medicine, vol. 9, no. 1, pp. 94-104.
Geraldes, C. F G C ; Brown, R. D. ; Cacheris, W. P. ; Koenig, S. H. ; Sherry, A. D. ; Spiller, M. / Evaluation of polyaza macrocylic methylene phosphonate chelates of Gd3+ ions as MRI contrast agents. In: Magnetic Resonance in Medicine. 1989 ; Vol. 9, No. 1. pp. 94-104.
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