title: Ultrasmall superparamagnetic iron oxide: an intravenous contrast agent for assessing lymph nodes with MR imaging.
abstract: An ultrasmall superparamagnetic iron oxide (USPIO) preparation was evaluated as a potential intravenous contrast agent for lymph nodes. Relaxation time measurements and magnetic resonance (MR) imaging were performed in rats with normal lymph nodes and in rats with lymph node metastases. In normal animals, lymph node relaxation times decreased maximally within 24-48 hours after intravenous administration of USPIO. Twenty-four hours after administration, the T2 of normal lymph nodes had decreased from 74 msec +/- 2.2 to 30 msec +/- 0.7 (USPIO, 40 mumol of iron per kilogram) or 15 msec +/- 0.0 (200 mumol Fe/kg), whereas the T2 of metastatic nodes did not change. MR imaging of the animal model of nodal metastases confirmed the hypothesis that intravenously administered USPIO decreases signal intensity of normal but not metastatic nodes. A single intravenous administration of USPIO may allow detection of nodal metastases on the basis of signal intensity characteristics rather than the currently used, insensitive size characteristics.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston.
authors.forename: R
authors.initials: R
authors.lastname: Weissleder
authors.forename: G
authors.initials: G
authors.lastname: Elizondo
authors.forename: J
authors.initials: J
authors.lastname: Wittenberg
authors.forename: A S
authors.initials: AS
authors.lastname: Lee
authors.forename: L
authors.initials: L
authors.lastname: Josephson
authors.forename: T J
authors.initials: TJ
authors.lastname: Brady
mesh_terms: D000818:Animals; D003287:Contrast Media; D004305:Dose-Response Relationship, Drug; D052203:Ferrosoferric Oxide; D007275:Injections, Intravenous; D007501:Iron / Q000008:administration & dosage / Q000493:pharmacokinetics; D008114:Liver Neoplasms, Experimental; D008198:Lymph Nodes / Q000378:metabolism / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D010087:Oxides; D010316:Particle Size; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D003287:Contrast Media; D010087:Oxides; D007501:Iron; D052203:Ferrosoferric Oxide