title: Improved detection of bone metastases from lung cancer in the thoracic cage using 5- and 1-mm axial images versus a new CT software generating rib unfolding images: comparison with standard ¹⁸F-FDG-PET/CT.
abstract: OBJECTIVE
  To evaluate the performance of a dedicated computed tomography (CT) software called "bone reading" generating rib unfolded images for improved detection of rib metastases in patients with lung cancer in comparison to readings of 5- and 1-mm axial CT images and (18)F-Fluordeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT).
  
  
  METHODS
  Ninety consecutive patients who underwent (18)F-FDG-PET/CT and chest CT scanning between 2012 and 2014 at our institution were analyzed retrospectively. Chest CT scans with 5- and 1-mm slice thickness were interpreted blindly and separately focused on the detection of rib metastases (location, number, cortical vs. medullary, and osteoblastic vs. sclerotic). Subsequent image analysis of unfolded 1 mm-based CT rib images was performed. For all three data sets the reading time was registered. Finally, results were compared to those of FDG-PET. Validation was based on FDG-PET positivity for osteolytic and mixed osteolytic/osteoblastic focal rib lesions and follow-up for sclerotic PET-negative lesions.
  
  
  RESULTS
  A total of 47 metastatic rib lesions were found on FDG-PET/CT plus another 30 detected by CT bone reading and confirmed by follow-up CT. Twenty-nine lesions were osteolytic, 14 were mixed osteolytic/osteoblastic, and 34 were sclerotic. On a patient-based analysis, CT (5 mm), CT (1 mm), and CT (1-mm bone reading) yielded a sensitivity, specificity, and accuracy of 76.5/97.3/93, 81.3/97.3/94, and 88.2/95.9/92, respectively. On segment-based (unfolded rib) analysis, the sensitivity, specificity, and accuracy of the three evaluations were 47.7/95.7/67, 59.5/95.8/77, and 94.8/88.2/92, respectively. Reading time for 5 mm/1 mm axial images and unfolded images was 40.5/50.7/21.56 seconds, respectively.
  
  
  CONCLUSIONS
  The use of unfolded rib images in patients with lung cancer improves sensitivity and specificity of rib metastasis detection in comparison to 5- and 1-mm CT slice reading. Moreover, it may reduce the reading time.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tübingen, Hoppe-Seyler-Strasse 3, D-72076 Tübingen, Germany. Electronic address: georg.homann@med.uni-tuebingen.de.
authors.forename: Georg
authors.initials: G
authors.lastname: Homann
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tübingen, Hoppe-Seyler-Strasse 3, D-72076 Tübingen, Germany.
authors.forename: Deedar F
authors.initials: DF
authors.lastname: Mustafa
authors.affiliation: Siemens AG, Healthcare, Forchheim, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Ditt
authors.affiliation: Department of Internal Medicine II, Eberhard-Karls-University Tübingen, Tübingen, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Spengler
authors.affiliation: Department of Internal Medicine II, Eberhard-Karls-University Tübingen, Tübingen, Germany.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Kopp
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tübingen, Hoppe-Seyler-Strasse 3, D-72076 Tübingen, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University Tübingen, Hoppe-Seyler-Strasse 3, D-72076 Tübingen, Germany.
authors.forename: Marius
authors.initials: M
authors.lastname: Horger
mesh_terms: D000368:Aged; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D008297:Male; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012272:Ribs / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D012984:Software; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: FDG-PET/CT; Lung cancer; bone metastasis; computed tomography; ribs; unfolded rib images