title: Diffusion Weighted Imaging Can Distinguish Benign from Malignant Mediastinal Tumors and Mass Lesions: Comparison with Positron Emission Tomography.
abstract: BACKGROUND
  Diffusion-weighted magnetic resonance imaging (DWI) makes it possible to detect malignant tumors based on the diffusion of water molecules. It is uncertain whether DWI is more useful than positron emission tomography-computed tomography (PET-CT) for distinguishing benign from malignant mediastinal tumors and mass lesions.
  
  
  METHODS
  Sixteen malignant mediastinal tumors (thymomas 7, thymic cancers 3, malignant lymphomas 3, malignant germ cell tumors 2, and thymic carcinoid 1) and 12 benign mediastinal tumors or mass lesions were assessed in this study. DWI and PET-CT were performed before biopsy or surgery.
  
  
  RESULTS
  The apparent diffusion coefficient (ADC) value (1.51±0.46x10(-3) mm2/sec) of malignant mediastinal tumors was significantly lower than that (2.96±0.86x10(-3) mm2/sec) of benign mediastinal tumors and mass lesions (P<0.0001). Maximum standardized uptake value (SUVmax) (11.30±11.22) of malignant mediastinal tumors was significantly higher than that (2.53±3.92) of benign mediastinal tumors and mass lesions (P=0.0159). Using the optimal cutoff value (OCV) 2.21x10(-3) mm2/sec for ADC and 2.93 for SUVmax, the sensitivity (100%) by DWI was not significantly higher than that (93.8%) by PET-CT for malignant mediastinal tumors. The specificity (83.3%) by DWI was not significantly higher than that (66.7%) for benign mediastinal tumors and mass lesions. The accuracy (92.9%) by DWI was not significantly higher than that (82.1%) by PET-CT for mediastinal tumors and mass lesions.
  
  
  CONCLUSIONS
  There was no significant difference between diagnostic capability of DWI and that of PET-CT for distinguishing mediastinal tumors and mass lesions. DWI is useful in distinguishing benign from malignant mediastinal tumors and mass lesions.
authors.affiliation: Department of Thoracic Surgery, Kanazawa Medical University, Daigaku, Uchinada, Ishikawa, Japan E-mail : usuda@kanazawa-med.ac.jp.
authors.forename: Katsuo
authors.initials: K
authors.lastname: Usuda
authors.forename: Sumiko
authors.initials: S
authors.lastname: Maeda
authors.forename: Nozomu
authors.initials: N
authors.lastname: Motono
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Ueno
authors.forename: Makoto
authors.initials: M
authors.lastname: Tanaka
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Machida
authors.forename: Munetaka
authors.initials: M
authors.lastname: Matoba
authors.forename: Naoto
authors.initials: N
authors.lastname: Watanabe
authors.forename: Hisao
authors.initials: H
authors.lastname: Tonami
authors.forename: Yoshimichi
authors.initials: Y
authors.lastname: Ueda
authors.forename: Motoyasu
authors.initials: M
authors.lastname: Sagawa
mesh_terms: D002276:Carcinoid Tumor / Q000175:diagnosis* / Q000473:pathology; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D008223:Lymphoma / Q000175:diagnosis* / Q000473:pathology; D008479:Mediastinal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D009373:Neoplasms, Germ Cell and Embryonal / Q000175:diagnosis* / Q000473:pathology; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D012372:ROC Curve; D013945:Thymoma / Q000175:diagnosis* / Q000473:pathology; D013953:Thymus Neoplasms / Q000175:diagnosis* / Q000473:pathology; D014057:Tomography, X-Ray Computed