Blood pool and liver enhancement in CT with liposomal lodixanol: comparison with lohexol.
OBJECTIVE
The authors compared the time course and blood pool and hepatic enhancement of three different doses of liposomal iodixanol with those of iohexol.


METHODS
A liposomal iodixanol formulation was prepared with 200 mg of iodine per milliliter total and 80 mg of iodine per milliliter encapsulated. Twelve normal New Zealand white rabbits divided into four groups received 75-, 100-, or 150-mg encapsulated iodine per kilogram doses of liposomal iodixanol or 2 mL/kg iohexol with 300 mg of iodine per milliliter. A liver section was scanned with serial computed tomography (CT) before the injection, immediately afterward, and at 1-minute intervals for 10 minutes. Region-of-interest measurements of the aorta and liver were plotted at each time point, and contrast enhancement was plotted as a function of time and iodine dose.


RESULTS
All liposomal iodixanol doses produced greater liver enhancement than iohexol. Results were significant (P < .05) for 100 mg and 150 mg iodine per kilogram dose groups at time points beyond 2 minutes. Peak hepatic enhancement (change in attenuation) was 54.9 HU +/- 7.6 with iohexol, compared with 59.6 HU +/- 6.1, 73.3 HU +/- 3.6, and 104.1 HU +/- 8.8 for 75, 100, and 150 mg encapsulated iodine per kilogram doses, respectively. Hepatic enhancement increased rapidly after injection of liposomal iodixanol, plateauing 2-3 minutes later. Blood pool enhancement decreased rapidly. Steady-state liver enhancement with liposomal iodixanol increased linearly with dose. Aortic enhancement was greater with iohexol.


CONCLUSIONS
Liposomal iodixanol yielded greater hepatic enhancement at lower total iodine doses than iohexol. Although liver enhancement occurred rapidly after injection, blood pool enhancement was brief.
Desser
T S
TS
Department of Radiology, VA Palo Alto Health Care System, CA 94304, USA.
Rubin
D L
DL
Muller
H
H
McIntire
G L
GL
Bacon
E R
ER
Toner
J L
JL
D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D004337:Drug Carriers; D007275:Injections, Intravenous; D007455:Iodine / Q000032:analysis; D007472:Iohexol / Q000493:pharmacokinetics; D008081:Liposomes; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging / Q000378:metabolism*; D008102:Liver Circulation; D008297:Male; D011817:Rabbits; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014283:Triiodobenzoic Acids / Q000493:pharmacokinetics*
D003287:Contrast Media; D004337:Drug Carriers; D008081:Liposomes; D014283:Triiodobenzoic Acids; D007472:Iohexol; D007455:Iodine; C044834:iodixanol