Computer-aided diagnosis for detection of cardiomegaly in digital chest radiographs

Takayuki Ishida, Shigehiko Katsuragawa, Koichi Chida, Heber MacMahon, Kunio Doi

Research output: Contribution to journalConference articlepeer-review

4 Citations (Scopus)


The cardio-thoracic ratio (CTR) is commonly measured manually for the evaluation of cardiomegaly. To determine the CTR automatically, we have developed a computerized scheme based on gray-level histogram analysis and an edge detection technique with feature analysis. The database used in this study consisted of 392 chest radiographs, which included 304 normals and 88 abnormals with cardiomegaly. The pixel size and the quantization level of the image were 0.175 mm and 1024, respectively. We performed a nonlinear density correction to maintain consistency in the density and contrast of the image. Initial heart edge detection was performed by selection of a certain range of pixel values in the histogram of a rectangular area at the center of a low-resolution image. Feature analysis with use of an edge gradient and with the orientation obtained by a Sobel operator was applied for accurate identification of the heart edges, which tend to have large edge gradients in a certain range of orientations. In addition, to determine the CTR, we detected the ribcage edges automatically by using image profile analysis. In 94.9% of all of the cases, the heart edges were detected accurately by use of this scheme. The area under the ROC curve (A z value) in distinguishing between normals and abnormals with cardiomegaly based on the CTR was 0.912. Because the CTR is measured automatically and quickly (in less than 1 sec.), radiologists could save reading time. The computerized scheme will be useful for the assessment of cardiomegaly on chest radiographs.

Original languageEnglish
Article number95
Pages (from-to)914-920
Number of pages7
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Issue numberII
Publication statusPublished - 2005 Aug 25
EventMedical Imaging 2005 - Image Processing - San Diego, CA, United States
Duration: 2005 Feb 132005 Feb 17


  • Cardio thoracic ratio
  • Cardiomegaly
  • Computer-aided diagnosis
  • Edge detection

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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