title: Noninvasive detection of clinically occult lymph-node metastases in prostate cancer.
abstract: BACKGROUND
  Accurate detection of lymph-node metastases in prostate cancer is an essential component of the approach to treatment. We investigated whether highly lymphotropic superparamagnetic nanoparticles, which gain access to lymph nodes by means of interstitial-lymphatic fluid transport, could be used in conjunction with high-resolution magnetic resonance imaging (MRI) to reveal small nodal metastases.
  
  
  METHODS
  Eighty patients with presurgical clinical stage T1, T2, or T3 prostate cancer who underwent surgical lymph-node resection or biopsy were enrolled. All patients were examined by MRI before and 24 hours after the intravenous administration of lymphotropic superparamagnetic nanoparticles (2.6 mg of iron per kilogram of body weight). The imaging results were correlated with histopathological findings.
  
  
  RESULTS
  Of the 334 lymph nodes that underwent resection or biopsy, 63 (18.9 percent) from 33 patients (41 percent) had histopathologically detected metastases. Of these 63 nodes, 45 (71.4 percent) did not fulfill the usual imaging criteria for malignancy. MRI with lymphotropic superparamagnetic nanoparticles correctly identified all patients with nodal metastases, and a node-by-node analysis had a significantly higher sensitivity than conventional MRI (90.5 percent vs. 35.4 percent, P<0.001) or nomograms.
  
  
  CONCLUSIONS
  High-resolution MRI with magnetic nanoparticles allows the detection of small and otherwise undetectable lymph-node metastases in patients with prostate cancer.
authors.affiliation: Massachusetts General Hospital and Harvard Medical School, Boston, USA.
authors.forename: Mukesh G
authors.initials: MG
authors.lastname: Harisinghani
authors.forename: Jelle
authors.initials: J
authors.lastname: Barentsz
authors.forename: Peter F
authors.initials: PF
authors.lastname: Hahn
authors.forename: Willem M
authors.initials: WM
authors.lastname: Deserno
authors.forename: Shahin
authors.initials: S
authors.lastname: Tabatabaei
authors.forename: Christine Hulsbergen
authors.initials: CH
authors.lastname: van de Kaa
authors.forename: Jean
authors.initials: J
authors.lastname: de la Rosette
authors.forename: Ralph
authors.initials: R
authors.lastname: Weissleder
mesh_terms: D000368:Aged; D001706:Biopsy; D003287:Contrast Media; D005290:Ferric Compounds; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D036103:Nanotechnology; D009367:Neoplasm Staging; D010316:Particle Size; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000473:pathology*; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide