[Magnetic resonance enhancement features of inflammatory lymph nodes with ultrasmall superparamagnetic iron oxide in rabbit model].
OBJECTIVE
To study magnetic resonance enhancement features of inflammatory lymph nodes using different doses of ultrasmall superparamagnetic iron oxide (USPIO) particles in order to establish a standardized protocol for USPIO enhanced magnetic resonance imaging of lymph nodes.


METHODS
A total of 12 healthy New Zealand rabbits were injected complete Freund's adjuvant in foot pad to establish popliteal inflammatory lymph node model. Different doses (45, 90, 135 micromol Fe/kg) of USPIO were injected intravenously. Magnetic resonance scans were performed before and after USPIO injection to observe the enhancement features of different groups. T2 signal intensity, T1 signal intensity, T2 x value, and T2 value were measured and T2 enhancement ratio was calculated at different time points.


RESULTS
Twenty-four hours after USPIO injection, there was no statistical difference in T2 signal intensity and T2 enhancement ratio between 90 and 135 micromol Fe/kg dose groups, but both were superior to 45 micromol Fe/kg group (P < 0.05). There were no statistical differences in T2 signal intensity, T1 signal intensity, T2 value, and T2 enhance ratio among different postcontrast time delays from 6 to 24 hours in 90 micromol Fe/kg group (P > 0.05), and signal reduction of lymph nodes peaked 18 hours after USPIO injection. Better images were acquired with a postcontrast delay of 18-24 hours.


CONCLUSIONS
Lymph nodes can be enhanced well with a dose of 90 micromol Fe/kg. Postcontrast delay of 18-24 hours is appropriate for acquiring satisfactory enhancement images.
Lei
Jing
J
Department of Radiology, PUMC Hospital, CAMS and PUMC, Beijing 100730, China.
Xue
Hua-Dan
HD
Li
Shuo
S
Li
Zhuo
Z
Jin
Zheng-Yu
ZY
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage; D003911:Dextrans / Q000008:administration & dosage; D007089:Image Enhancement / Q000379:methods*; D008199:Lymphadenitis / Q000175:diagnosis* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000008:administration & dosage; D008297:Male; D011817:Rabbits; D011897:Random Allocation
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10