Triple-quantum-filtered (23)Na NMR spectroscopy of subcutaneously implanted 9l gliosarcoma in the rat in the presence of TmDOTP(5-1).
The utility of triple-quantum (TQ)-filtered (23)Na NMR spectroscopy for discriminating between intra- and extracellular Na(+)(Na(i)(+) and Na(e)(+), respectively) in a solid tumor in vivo was evaluated using TmDOTP(5-) as a (23)Na shift reagent. Infusion of 80 mM TmDOTP(5-) without added Ca(2+) produced baseline-resolved Na(i)(+) and Na(e)(+) peaks in both single-quantum (SQ) and TQ-filtered (23)Na spectra. The Na(i)(+) signal represented 22+/-4% of the SQ spectrum, but 59+/-10% of the TQ-filtered spectrum. Therefore, the Na(i)(+) contribution in TQ-filtered spectra is much higher than in SQ spectra. Both SQ and TQ-filtered Na(i)(+) signals increased by about 75% 1 h after sacrificing the animal. The TQ-filtered relaxation times did not change during this time, indicating that changes observed in TQ-filtered spectra collected with a preparation time of 3 ms represent changes in the concentration of sodium ions contributing to the TQ-filtered signal. Similar experiments were conducted without TmDOTP(5-) to determine changes in the Na(e)(+) signal in the absence of the shift reagent. The changes in total SQ and TQ-filtered signals 1 h after sacrificing the animal showed that the SQ Na(e)(+) signal decreased by approximately 35%, while the TQ-filtered Na(e)(+) signal did not change significantly. This demonstrates that the TQ-filtered (23)Na signal is relatively insensitive to changes in Na(e)(+) content. To our knowledge, this work represents the first evaluation of multiple-quantum-filtered (23)Na spectroscopy to discriminate between intra- and extracellular Na(+) in a solid tumor in vivo.
Winter
P M
PM
Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, 19104-6100, USA.
Bansal
N
N
D000818:Animals; D002478:Cells, Cultured; D018316:Gliosarcoma / Q000175:diagnosis*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D009368:Neoplasm Transplantation; D009942:Organometallic Compounds; D009943:Organophosphorus Compounds; D011789:Quantum Theory; D051381:Rats; D011916:Rats, Inbred F344; D012867:Skin; D012964:Sodium; D013932:Thulium
D009942:Organometallic Compounds; D009943:Organophosphorus Compounds; C069929:thulium(III) 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetramethylenephosphonate; D013932:Thulium; D012964:Sodium