title: Differential diagnosis of osteoblastic metastases from bone islands in patients with lung cancer by single-source dual-energy CT: advantages of spectral CT imaging.
abstract: OBJECTIVE
  To evaluate the diagnostic efficacy of spectral CT for the differentiation of osteoblastic metastases (OBMs) from bone islands (BIs) in patients with lung cancer.
  
  
  METHODS
  In 94 patients with lung cancer who underwent spectral CT, focal hyperdense lesions in vertebral bodies were diagnosed as OBMs or BIs. Regions of interest were placed within each lesion to measure the mean CT value and its standard deviation (SD) on polychromatic single-energy CT (SECT) at 140 kVp and dual-energy virtual monochromatic spectral (VMS) images. The mean bone (Dbone(wa)) and water densities (Dwa(bone)) of each lesion were also measured. The slope (k) of the spectral curve was calculated. Independent-sample t-test was used to compare those values between OBMs and BIs. Receiver operator characteristic analysis was performed to compare the area under curve (AUC) for the differentiation of OBMs from BIs.
  
  
  RESULTS
  A total of 79 OBMs and 43 BIs were confirmed. The CT and SD values on SECT at 140 kVp and VMS images at 50-130 keV, k value, and Dbone(wa) for OBMs were significantly lower than for BIs; Dwa(bone) was significantly higher for OBMs than for BIs (p<0.05 for all). The AUC for the SD value at 110 keV was the highest among those parameters. The optimal cut-off value for this differentiation was 68.6 HU for the SD value on VMS images at 110 keV with sensitivity of 93.0% and specificity of 93.3%.
  
  
  CONCLUSIONS
  Spectral CT is helpful for the differentiation of OBMs from BIs in patients with lung cancer, particularly using SD of the CT value on high-energy VMS images.
authors: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing 116011, China. Electronic address: dyy1026@sina.com.
authors: Yue
authors: Y
authors: Dong
authors: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing 116011, China. Electronic address: chouxiong@sohu.com.
authors: Shaowei
authors: S
authors: Zheng
authors: Department of Radiology, Tokyo Women's Medical University Medical Center East, Tokyo 116-8567, Japan. Electronic address: machira@dnh.twmu.ac.jp.
authors: Haruhiko
authors: H
authors: Machida
authors: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing 116011, China. Electronic address: wangbing19831003@163.com.
authors: Bing
authors: B
authors: Wang
authors: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing 116011, China. Electronic address: dmu_liuailian@126.com.
authors: Ailian
authors: A
authors: Liu
authors: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing 116011, China. Electronic address: yijunliu1965@126.com.
authors: Yijun
authors: Y
authors: Liu
authors: Department of Nuclear Medicine, The First Affiliated Hospital of Dalian Medical University, Liaoning 116011, China. Electronic address: zhhw2000@126.com.
authors: Xin
authors: X
authors: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000556:secondary*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D010006:Osteoblasts / Q000473:pathology*; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015900:Radiography, Dual-Energy Scanned Projection; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: Bone island; Dual-energy CT; Lung cancer; Monochromatic image; Osteoblastic metastasis