title: A study of computer-aided diagnosis for pulmonary nodule: comparison between classification accuracies using calculated image features and imaging findings annotated by radiologists.
abstract: OBJECTIVE
  In our previous study, we developed a computer-aided diagnosis (CADx) system using imaging findings annotated by radiologists. The system, however, requires radiologists to input many imaging findings. In order to reduce such an interaction of radiologists, we further developed a CADx system using derived imaging findings based on calculated image features, in which the system only requires few user operations. The purpose of this study is to check whether calculated image features (CFT) or derived imaging findings (DFD) can represent information in imaging findings annotated by radiologists (AFD).
  
  
  METHODS
  We calculate 2282 image features and derive 39 imaging findings by using information on a nodule position and its type (solid or ground-glass). These image features are categorized into shape features, texture features and imaging findings-specific features. Each imaging finding is derived based on each corresponding classifier using random forest. To check whether CFT or DFD can represent information in AFD, under an assumption that the accuracies of classifiers are the same if information included in input is the same, we constructed classifiers by using various types of information (CTT, DFD and AFD) and compared accuracies on an inferred diagnosis of a nodule. We employ SVM with RBF kernel as classifier to infer a diagnosis name.
  
  
  RESULTS
  Accuracies of classifiers using DFD, CFT, AFD and CFT [Formula: see text] AFD were 0.613, 0.577, 0.773 and 0.790, respectively. Concordance rates between DFD and AFD of shape findings, texture findings and surrounding findings were 0.644, 0.871 and 0.768, respectively.
  
  
  CONCLUSIONS
  The results suggest that CFT and AFD are similar information and CFT represent only a portion of AFD. Particularly, CFT did not contain shape information in AFD. In order to decrease an interaction of radiologists, a development of a method which overcomes these problems is necessary.
authors.affiliation: Canon Inc., 70-1, Yanagi-cho, Saiwai-ku, Kawasaki, Kanagawa, 212-8602, Japan. kawagishi.masami@canon.co.jp.
authors.forename: Masami
authors.initials: M
authors.lastname: Kawagishi
authors.affiliation: Canon Inc., 70-1, Yanagi-cho, Saiwai-ku, Kawasaki, Kanagawa, 212-8602, Japan.
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.affiliation: Canon Inc., 70-1, Yanagi-cho, Saiwai-ku, Kawasaki, Kanagawa, 212-8602, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Furukawa
authors.affiliation: Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sekiguchi
authors.affiliation: Human Health Science, Graduate School of Medicine, Kyoto University, 53 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Sakai
authors.affiliation: Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kubo
authors.affiliation: Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yakami
authors.affiliation: Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Fujimoto
authors.affiliation: Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Sakamoto
authors.affiliation: Department of Medical Science, Kyoto College of Medical Science, 1-3, Imakita, Oyama-Higashimachi, Sonobe-cho, Nantan, Kyoto, 622-0041, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Emoto
authors.affiliation: Canon Inc., 70-1, Yanagi-cho, Saiwai-ku, Kawasaki, Kanagawa, 212-8602, Japan.
authors.forename: Gakuto
authors.initials: G
authors.lastname: Aoyama
authors.affiliation: Canon Inc., 70-1, Yanagi-cho, Saiwai-ku, Kawasaki, Kanagawa, 212-8602, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Iizuka
authors.affiliation: Canon Inc., 70-1, Yanagi-cho, Saiwai-ku, Kawasaki, Kanagawa, 212-8602, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Nakagomi
authors.affiliation: Canon Inc., 70-1, Yanagi-cho, Saiwai-ku, Kawasaki, Kanagawa, 212-8602, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002648:Child; D002675:Child, Preschool; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D015588:Observer Variation; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D000072177:Radiologists; D011871:Radiology / Q000379:methods; D015203:Reproducibility of Results; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D060388:Support Vector Machine; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
keywords: Calculated image features; Chest CT; Computer-aided diagnosis; Derived imaging findings