Oral Radiology

, Volume 35, Issue 2, pp 143–151 | Cite as

Improvement of region of interest extraction and scanning method of computer-aided diagnosis system for osteoporosis using panoramic radiographs

  • Takashi NakamotoEmail author
  • Akira Taguchi
  • Rinus Gerardus Verdonschot
  • Naoya Kakimoto
Original Article



Patients undergoing osteoporosis treatment benefit greatly from early detection. We previously developed a computer-aided diagnosis (CAD) system to identify osteoporosis using panoramic radiographs. However, the region of interest (ROI) was relatively small, and the method to select suitable ROIs was labor-intensive. This study aimed to expand the ROI and perform semi-automatized extraction of ROIs. The diagnostic performance and operating time were also assessed.


We used panoramic radiographs and skeletal bone mineral density data of 200 postmenopausal women. Using the reference point that we defined by averaging 100 panoramic images as the lower mandibular border under the mental foramen, a 400 × 100-pixel ROI was automatically extracted and divided into four 100 × 100-pixel blocks. Valid blocks were analyzed using program 1, which examined each block separately, and program 2, which divided the blocks into smaller segments and performed scans/analyses across blocks. Diagnostic performance was evaluated using another set of 100 panoramic images.


Most ROIs (97.0%) were correctly extracted. The operation time decreased to 51.4% for program 1 and to 69.3% for program 2. The sensitivity, specificity, and accuracy for identifying osteoporosis were 84.0, 68.0, and 72.0% for program 1 and 92.0, 62.7, and 70.0% for program 2, respectively. Compared with the previous conventional system, program 2 recorded a slightly higher sensitivity, although it occasionally also elicited false positives.


Patients at risk for osteoporosis can be identified more rapidly using this new CAD system, which may contribute to earlier detection and intervention and improved medical care.


Diagnostic imaging Osteoporosis Radiography Mandible 


Compliance with ethical standards

Conflict of interest

Nakamoto T, Taguchi A, Verdonschot RG, and Kakimoto N declare that they have no conflict of interest.

Human rights statement and informed consent

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 (5). Informed consent was obtained from all patients for being included in the study.

Animal rights statement

This article does not contain any studies with animal subjects performed by the author.


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Copyright information

© Japanese Society for Oral and Maxillofacial Radiology and Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Department of Oral and Maxillofacial RadiologyHiroshima University HospitalMinami-kuJapan
  2. 2.Department of Oral and Maxillofacial RadiologyMatsumoto Dental UniversityNaganoJapan
  3. 3.Department of Oral and Maxillofacial Radiology, Institute of Biomedical and Health ScienceHiroshima UniversityHiroshimaJapan

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