[Ultra-small superparamagnetic iron oxide particles: the signal behavior and relaxation times of the bone marrow after repeated i.v. application in the pig model at 1.5 tesla].
OBJECTIVE
Evaluation of the influence of an iron-containing MR contrast agent on the signal behaviour and the relaxation time of the bone marrow at 1.5 tesla after repeated doses.


METHODS
14 pigs received i.v. on days 1, 9, and 15 ultra-small (core diameter 6-8 nm) superparamagnetic iron oxide particles at doses of 20 (low dose = LD) or 200 mumol/kg body weight (high dose = HD).


RESULTS
Following the first administration a dose-independent reduction in the bone-marrow signal intensity in the T2-weighted gradient-echo sequence (FFE) was observed together with a reduction in the T1 and T2 relaxation times. Following the second application there were no further signal-reductions in the HD-group; in contrast, there was a signal reduction in the LD-group, made possible by a signal recovery in the meantime. On the other hand, the relaxation times T1 and T2 were shortened after each administration of contrast medium.


CONCLUSIONS
Nano-SIPS result at both doses in a signal reduction in the bone marrow. Only in the LD-group may repeated examinations with new contrast agent offer diagnostically sufficient images. Relaxometry shows a shortening of T1 as well as T2. This effect could be summed up after repeated doses. Almost no iron remained in the medullary space three weeks after i.v. administration of the contrast agent, which suggests mobilization and metabolization.
Cihal
S
S
Radiologische Klinik, Abteilung Röntgendiagnostik, Universität Hamburg-Eppendorf.
Maas
R
R
Delling
G
G
Klich
S
S
Nielsen
P
P
Lodemann
K P
KP
Bücheler
E
E
D000818:Animals; D001853:Bone Marrow / Q000033:anatomy & histology / Q000378:metabolism; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D005260:Female; D005269:Femur; D052203:Ferrosoferric Oxide; D007501:Iron / Q000008:administration & dosage / Q000493:pharmacokinetics; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D010087:Oxides / Q000008:administration & dosage / Q000493:pharmacokinetics; D010316:Particle Size; D013552:Swine; D013997:Time Factors
D003287:Contrast Media; D010087:Oxides; D007501:Iron; D052203:Ferrosoferric Oxide