title: Content-based retrieval of brain tumor in contrast-enhanced MRI images using tumor margin information and learned distance metric.
abstract: OBJECTIVE
  A content-based image retrieval (CBIR) method for T1-weighted contrast-enhanced MRI (CE-MRI) images of brain tumors is presented for diagnosis aid. The method is thoroughly evaluated on a large image dataset.
  
  
  METHODS
  Using the tumor region as a query, the authors' CBIR system attempts to retrieve tumors of the same pathological category. Aside from commonly used features such as intensity, texture, and shape features, the authors use a margin information descriptor (MID), which is capable of describing the characteristics of tissue surrounding a tumor, for representing image contents. In addition, the authors designed a distance metric learning algorithm called Maximum mean average Precision Projection (MPP) to maximize the smooth approximated mean average precision (mAP) to optimize retrieval performance.
  
  
  RESULTS
  The effectiveness of MID and MPP algorithms was evaluated using a brain CE-MRI dataset consisting of 3108 2D scans acquired from 235 patients with three categories of brain tumors (meningioma, glioma, and pituitary tumor). By combining MID and other features, the mAP of retrieval increased by more than 6% with the learned distance metrics. The distance metric learned by MPP significantly outperformed the other two existing distance metric learning methods in terms of mAP. The CBIR system using the proposed strategies achieved a mAP of 87.3% and a precision of 89.3% when top 10 images were returned by the system. Compared with scale-invariant feature transform, the MID, which uses the intensity profile as descriptor, achieves better retrieval performance.
  
  
  CONCLUSIONS
  Incorporating tumor margin information represented by MID with the distance metric learned by the MPP algorithm can substantially improve the retrieval performance for brain tumors in CE-MRI.
authors.affiliation: School of Biomedical Engineering, Southern Medical University, Guangzhou, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.forename: Qianjin
authors.initials: Q
authors.lastname: Feng
authors.forename: Mei
authors.initials: M
authors.lastname: Yu
authors.forename: Zhentai
authors.initials: Z
authors.lastname: Lu
authors.forename: Yang
authors.initials: Y
authors.lastname: Gao
authors.forename: Yikai
authors.initials: Y
authors.lastname: Xu
authors.forename: Wufan
authors.initials: W
authors.lastname: Chen
mesh_terms: D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D003287:Contrast Media; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*
chemical_list: D003287:Contrast Media