title: Mediastinal lymph nodes: assessment with diffusion-weighted MR imaging.
abstract: OBJECTIVE
  To prospectively determine whether the diffusion-weighted magnetic resonance imaging is useful to distinguish between malignant and benign mediastinal lymph nodes.
  
  
  METHODS
  Thirty-five patients (14 women, 21 men; mean age 52 years) with 91 lymph nodes in the mediastinum detected by computed tomography underwent 1.5 Tesla (T) diffusion-weighted MR imaging before mediastinoscopy (n = 29) and mediastinotomy (n = 6). Diffusion-weighted MR images were acquired with a b factor of 50, and 400 s/mm(2) using single-shot echo-planar sequence.
  
  
  RESULTS
  Of the 35 patients, 18 had diagnosis of malignant tumor. Of the 18 patients with tumor, 8 had nonsmall cell carcinoma, and 10 had small cell carcinoma. Ninety-one mediastinal lymph nodes were detected in the 35 untreated patients: 19 were pathologically diagnosed as metastatic lymph nodes, and 72 lymph nodes were diagnosed as nonmetastatic lymph nodes, including 50 sarcoidosis, 14 reactive lymphoid hyperplasia, and 8 necrotizing granulamatous lymphadenitis. The apparent diffusion coefficient (ADC) was significantly lower in metastatic lymph nodes (1.012 +/- 0.025 x 10(-3) mm(2)/s; P < 0.0005) than in benign lymph nodes (1.511 +/- 0.075 x 10(-3) mm(2)/s). On the ADC map, malignant nodes showed hyperintense (n = 2, 10.52%), hypointense (n = 14, 73.68%), and mixed intensity (n = 3; 15.78%), whereas benign nodes showed hyperintense (n = 57; 79.16%), hypointense (n = 3; 41.6%), isointense (n = 6; 8.33%), and mixed intensity (n = 6; 8.33%).
  
  
  CONCLUSIONS
  Diffusion-weighted MR with ADC value and signal intensity can be useful in differentiation of malignant and benign mediastinal lymph nodes.
authors.affiliation: Medical School of Karadeniz Technical University, Farabi Hospital, Department of Radiology, Trabzon, Turkey. polatkosucu@hotmail.com
authors.forename: Polat
authors.initials: P
authors.lastname: Koşucu
authors.forename: Celal
authors.initials: C
authors.lastname: Tekinbaş
authors.forename: Muharrem
authors.initials: M
authors.lastname: Erol
authors.forename: Ahmet
authors.initials: A
authors.lastname: Sari
authors.forename: Halil
authors.initials: H
authors.lastname: Kavgaci
authors.forename: Funda
authors.initials: F
authors.lastname: Oztuna
authors.forename: Safak
authors.initials: S
authors.lastname: Ersöz
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008175:Lung Neoplasms / Q000473:pathology*; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008482:Mediastinum / Q000473:pathology*; D008875:Middle Aged; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed