Detection of experimental hepatic tumors using long circulating superparamagnetic particles.
OBJECTIVE
To evaluate the potential of an iron oxide-based MR contrast agent for the detection and delineation of experimental liver tumors during the early vascular phase of the compound.


METHODS
Superparamagnetic blood pool agent (SBPA) was administered intravenously to rabbits bearing VX2 tumors. Images were acquired before the injection, immediately after, and 1 or 3 weeks later. The variations of signal intensity were measured in the tumors and in several tissues for various T1-weighted spin-echo, T2-weighted fast spin-echo, and T2-weighted gradient-recalled-echo sequences.


RESULTS
Fourteen and 12 of the 16 tumors were detected immediately after SBPA injection using, respectively, the T2-weighted fast spin-echo and T2-weighted gradient-recalled-echo sequences. A significant decrease in signal intensity was observed in well-perfused organs, and blood signal was abolished even at the lowest injected dose and using a T1-weighted sequence. In the late phase, the loss in signal intensity of the liver was even more pronounced.


CONCLUSIONS
The dominant T2 effect of SBPA induces an increase in the tumor-to-liver and tumor-to-blood contrast during the vascular phase, improving the detection of the tumors and allowing the distinction between small lesions and vessels through plane. This effect on the liver signal persists for several days because of the incorporation of SBPA in the reticuloendothelial system.
Sayegh
Y
Y
Départment de Radiologie, H pital Universitaire de Genéve, Switzerland.
Pochon
S
S
Vallée
J P
JP
Becker
M
M
Lazeyras
F
F
Tournier
H
H
Hyacinthe
R
R
Fouillet
X
X
Terrier
F
F
D000818:Animals; D003287:Contrast Media; D005290:Ferric Compounds; D052203:Ferrosoferric Oxide; D008113:Liver Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D009374:Neoplasms, Experimental / Q000473:pathology*; D011817:Rabbits
D003287:Contrast Media; D005290:Ferric Compounds; C427127:superparamagnetic blood pool agent; D052203:Ferrosoferric Oxide