title: Differentiating benign from malignant bone tumors using fluid-fluid level features on magnetic resonance imaging.
abstract: OBJECTIVE
  To analyze different fluid-fluid level features between benign and malignant bone tumors on magnetic resonance imaging (MRI).
  
  
  METHODS
  This study was approved by the hospital ethics committee. We retrospectively analyzed 47 patients diagnosed with benign (n = 29) or malignant (n = 18) bone tumors demonstrated by biopsy/surgical resection and who showed the intratumoral fluid-fluid level on pre-surgical MRI. The maximum length of the largest fluid-fluid level and the ratio of the maximum length of the largest fluid-fluid level to the maximum length of a bone tumor in the sagittal plane were investigated for use in distinguishing benign from malignant tumors using the Mann-Whitney U-test and a receiver operating characteristic (ROC) analysis. Fluid-fluid level was categorized by quantity (multiple vs. single fluid-fluid level) and by T1-weighted image signal pattern (high/low, low/high, and undifferentiated), and the findings were compared between the benign and malignant groups using the χ(2) test.
  
  
  RESULTS
  The ratio of the maximum length of the largest fluid-fluid level to the maximum length of bone tumors in the sagittal plane that allowed statistically significant differentiation between benign and malignant bone tumors had an area under the ROC curve of 0.758 (95% confidence interval, 0.616-0.899). A cutoff value of 41.5% (higher value suggests a benign tumor) had sensitivity of 73% and specificity of 83%.
  
  
  CONCLUSIONS
  The ratio of the maximum length of the largest fluid-fluid level to the maximum length of a bone tumor in the sagittal plane may be useful to differentiate benign from malignant bone tumors.
authors.affiliation: Department of Radiology, The Third Hospital of Hebei Medical University, Hebei Province Biomechanical Key Laborary of Orthopedics, Shijiazhuang, Hebei 050051, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Radiology, The Third Hospital of Hebei Medical University, Hebei Province Biomechanical Key Laborary of Orthopedics, Shijiazhuang, Hebei 050051, China.
authors.forename: Jian-Ling
authors.initials: JL
authors.lastname: Cui
authors.affiliation: Department of Radiology, The Third Hospital of Hebei Medical University, Hebei Province Biomechanical Key Laborary of Orthopedics, Shijiazhuang, Hebei 050051, China.
authors.forename: Sheng-Jie
authors.initials: SJ
authors.lastname: Cui
authors.affiliation: Department of Radiology, The Third Hospital of Hebei Medical University, Hebei Province Biomechanical Key Laborary of Orthopedics, Shijiazhuang, Hebei 050051, China.
authors.forename: Ying-Cai
authors.initials: YC
authors.lastname: Sun
authors.affiliation: Department of Radiology, The Third Hospital of Hebei Medical University, Hebei Province Biomechanical Key Laborary of Orthopedics, Shijiazhuang, Hebei 050051, China.
authors.forename: Feng-Zhen
authors.initials: FZ
authors.lastname: Cui
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001859:Bone Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000601:surgery; D002648:Child; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011230:Precancerous Conditions / Q000175:diagnosis / Q000000981:diagnostic imaging*; D012372:ROC Curve; D011859:Radiography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D055815:Young Adult
keywords: Bone neoplasm; Fluid-fluid level; Magnetic resonance imaging