title: Comparison of two different iron oxide-based contrast agents for discrimination of benign and malignant lymph nodes.
abstract: OBJECTIVE
  The aim of this study was to investigate the performance of 2 different ultrasmall superparamagnetic iron oxide particles-based contrast agents for intravascular magnetic resonance lymphography in normal, inflammatory, and tumor-bearing lymph nodes in rabbits.
  
  
  METHODS
  Two USPIO agents were assessed: Sinerem and P904 (both Guerbet Research, Aulnay-sous-Bois, France). Signal change of popliteal and paraaortic lymph nodes were studied in VX-2 tumor-bearing rabbits (n = 4) and rabbits in whom complete Freund adjuvant had been applied (n = 6). Image acquisition was performed before and 5 to 120 minutes and 24 hours after bolus injection of Sinerem (n = 5) and P904 (n = 5). Lymph node size was assessed and signal-to-noise ratios of lymph nodes were calculated. The contrast agents were compared regarding nodal signal changes over time. Furthermore, sensitivities, specificities, and negative and positive predictive values were calculated for both contrast agents, with histopathology serving as the standard of reference.
  
  
  RESULTS
  No statistically significant size differences were detected between normal, reactively enlarged and tumor-infiltrated lymph nodes. Signal change over time showed greater differences between benign and metastatic lymph nodes for P904 especially at 24 hours after injection, whereas Sinerem showed the highest signal loss in benign nodes. After 24 hours, P904 showed a higher sensitivity (0.75 vs 0.67) and higher specificity (1 vs 0.94) compared with Sinerem. At earlier time points, sensitivity for Sinerem was lower (0.33), whereas for P904, sensitivity at 120 minutes was as good as after 24 hours (0.75).
  
  
  CONCLUSIONS
  Magnetic resonance lymphography with USPIO contrast agents allows for differentiation of reactively enlarged lymph nodes compared with metastatic nodes. P904 yielded higher sensitivity and specificity values, with higher signal differences between benign and malignant enlarged lymph nodes. Furthermore, diagnosis seems to be possible earlier. This agent therefore seems to be a promising tool for staging cancer patient.
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Germany. 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; D004195:Disease Models, Animal; D005290:Ferric Compounds; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology; D008220:Lymphography; D008279:Magnetic Resonance Imaging; D008297:Male; D011237:Predictive Value of Tests; D011817:Rabbits; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds