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Persistent contrast enhancement by sterically stabilized paramagnetic liposomes in murine melanoma
Author(s) -
Bertini Ivano,
Bianchini Francesca,
Calorini Lido,
Colagrande Stefano,
Fragai Marco,
Franchi Alessandro,
Gallo Oreste,
Gavazzi Cinzia,
Luchinat Claudio
Publication year - 2004
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.20189
Subject(s) - liposome , gadolinium , in vivo , chemistry , paramagnetism , nuclear magnetic resonance , polyethylene glycol , relaxation (psychology) , melanoma , biophysics , medicine , cancer research , biochemistry , biology , physics , organic chemistry , quantum mechanics , microbiology and biotechnology
Abstract In the present research, we investigated the use of paramagnetic liposomes as contrast agents (CAs) for the detection of solid tumors. The liposomes were sterically stabilized by a polyethylene glycol (PEG) coating, and their size was constrained to ∼100 nm. Dimyristoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐diethylene‐triaminepentaacetate (DMPE‐DTPA) was used as the gadolinium‐carrying fatty acid chain. The relaxation properties were characterized through nuclear magnetic relaxation dispersion (NMRD) measurements, and analyzed with the use of theories and computer programs that are adequate for slowly rotating systems. Their relaxivity at 1.5 T was found to be acceptable for in vivo use. We then tested the liposomes against B16‐F10 murine melanomas using standard T 1 ‐weighted schemes at 1.5 T, and concentrations corresponding to 0.03 mmol/kg of gadolinium (i.e., three to six times lower than the concentration of the small gadolinium complexes in clinical use). The blood half‐life was found to be 120 ± 20 min. The experiments show a good contrast enhancement in the tumor (33% ± 22%) 2 hr after administration, a further increase (43 ± 27%) 20 hr after administration, and a decrease (25% ± 14%) 54 hr after administration. High persistence of the CA was also observed in the liver and intestine, as expected in a hepatobiliar excretion pathway. Magn Reson Med 52:669–672, 2004. © 2004 Wiley‐Liss, Inc.