title: Lymphotropic nanoparticle-enhanced MRI for independent prediction of lymph node malignancy: a logistic regression model.
abstract: OBJECTIVE
  The purpose of this study was to determine whether use of lymphotropic nanoparticle-enhanced MRI can improve the ability to characterize lymph nodes as benign or malignant beyond size criteria alone.
  
  
  METHODS
  The cases of 42 consecutively registered patients with a known primary malignant tumor of the genitourinary tract who underwent both lymphotropic nanoparticle-enhanced MRI and CT-guided biopsy of a lymph node at our institution from 2000 to 2005 were retrospectively identified. Lymphotropic nanoparticle-enhanced MRI included T2(*)-weighted gradient-recalled echo imaging before and 24-36 hours after i.v. administration of lymphotropic iron oxide nanoparticles. Two positivity criteria for lymph node malignancy were evaluated independently: lack of nanoparticle uptake at lymphotropic nanoparticle-enhanced MRI and short-axis length of 1 cm or greater. Sensitivity and specificity were calculated for each criterion with biopsy results as the standard of reference. Logistic regression analysis was used to determine the association (odds ratio) between lymphotropic nanoparticle-enhanced MRI findings and the presence of lymph node malignancy when controlling for short-axis length.
  
  
  RESULTS
  Metastatic lesions were detected at histologic examination in 67% (28/42) of nodes. According to the lymphotropic nanoparticle-enhanced MRI criterion, sensitivity for malignancy was 100% (28/28 nodes), and specificity was 64% (9/14 nodes). According to the short-axis criterion, sensitivity was 79% (22/28 nodes), and specificity was 21% (3/14 nodes). In multivariate analysis, when controlling for short-axis length, the finding of malignancy at lymphotropic nanoparticle-enhanced MRI was an independent predictor of the presence of malignancy (odds ratio, 61.0; 95% CI, 8.0 to infinity; p < 0.0001).
  
  
  CONCLUSIONS
  Use of lymphotropic nanoparticle-enhanced MRI may improve ability to characterize lymph nodes beyond size criteria alone. Our results emphasize the need to further assess lymphotropic nanoparticle-enhanced MRI in prospective large-scale studies with wider variation in the distribution of lymph node sizes and primary malignancies.
authors.affiliation: Department of Radiology, Institute for Technology Assessment, Massachusetts General Hospital, 101 Merrimac St., 10th fl., Boston, MA 02114, USA.
authors.forename: Pari V
authors.initials: PV
authors.lastname: Pandharipande
authors.forename: Jose T
authors.initials: JT
authors.lastname: Mora
authors.forename: Raul N
authors.initials: RN
authors.lastname: Uppot
authors.forename: Alexander
authors.initials: A
authors.lastname: Goehler
authors.forename: Martha
authors.initials: M
authors.lastname: Braschi
authors.forename: Elkan F
authors.initials: EF
authors.lastname: Halpern
authors.forename: G Scott
authors.initials: GS
authors.lastname: Gazelle
authors.forename: Mukesh G
authors.initials: MG
authors.lastname: Harisinghani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage; D003911:Dextrans / Q000008:administration & dosage; D005260:Female; D052203:Ferrosoferric Oxide / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted; D016015:Logistic Models; D008207:Lymphatic Metastasis / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008297:Male; D008875:Middle Aged; D053758:Nanoparticles; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10; D052203:Ferrosoferric Oxide