title: Discrimination of benign and malignant lymph nodes at 7.0T compared to 1.5T magnetic resonance imaging using ultrasmall particles of iron oxide: a feasibility preclinical study.
abstract: OBJECTIVE
  To investigate the feasibility and performance of 7T magnetic resonance imaging compared to 1.5T imaging to discriminate benign (normal and inflammatory changed) from tumor-bearing lymph nodes in rabbits using ultrasmall particles of iron oxide (USPIO)-based contrast agents.
  
  
  METHODS
  Six New Zealand White rabbits were inoculated with either complete Freund's adjuvant cell suspension (n = 3) to induce reactively enlarged lymph nodes or with VX2 tumor cells to produce metastatic lymph nodes (n = 3). Image acquisition was performed before and 24 hours after bolus injection of an USPIO contrast agent at 1.5T and afterward at 7T using T1-weighted and T2*-weighted sequences. Sensitivities, specificities, and negative and positive predictive values for the detection of lymph node metastases were calculated for both field strengths with histopathology serving as reference standard. Sizes of lymph nodes with no, inflammatory, and malignant changes were compared using a Mann-Whitney U-test.
  
  
  RESULTS
  All 24 lymph nodes were detected at 1.5T as well as at 7T. At 1.5T, sensitivity amounted to 0.67, while specificity reached a value of 1. At the higher field strength (7T), imaging was able to reach sensitivity and specificity values of 1. No statistical differences were detected concerning lymph node sizes.
  
  
  CONCLUSIONS
  Magnetic resonance lymphography with USPIO contrast agents allows for differentiation of normal and reactively enlarged lymph nodes compared to metastatic nodes. First experiments at 7T show promising results compared to 1.5T, which have to be evaluated in further trials.
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstrasse 55, 45122 Essen, Germany. Electronic address: Sonja.Kinner@uni-due.de.
authors.forename: Sonja
authors.initials: S
authors.lastname: Kinner
authors.forename: Stefan
authors.initials: S
authors.lastname: Maderwald
authors.forename: Juliane
authors.initials: J
authors.lastname: Albert
authors.forename: Nina
authors.initials: N
authors.lastname: Parohl
authors.forename: Claire
authors.initials: C
authors.lastname: Corot
authors.forename: Philippe
authors.initials: P
authors.lastname: Robert
authors.forename: Hideo A
authors.initials: HA
authors.lastname: Baba
authors.forename: Jörg
authors.initials: J
authors.lastname: Barkhausen
mesh_terms: D000818:Animals; D003287:Contrast Media; D003911:Dextrans; D003937:Diagnosis, Differential; D004195:Disease Models, Animal; D005240:Feasibility Studies; D005290:Ferric Compounds; D007089:Image Enhancement / Q000379:methods; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D058185:Magnetite Nanoparticles; D008297:Male; D015588:Observer Variation; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D003911:Dextrans; D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10; C000499:ferric oxide
keywords: 7T MRI; Magnetic resonance imaging; contrast agents; lymphography; ultrasmall particles of iron oxide (USPIO)