Normal mastoid air cell system geometry: Has surface area been overestimated?

Sung Wan Byun, Seung Sin Lee, Jin Young Park, Jeong Hyun Yoo

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Objectives. The aim of this study was to emphasize the necessity of a standard in segmentation threshold and algorithm for measuring volume and surface area of mastoid air cell system (MACS). Methods. First, we obtained axial computed tomography scans of 54 normal temporal bones from 27 subjects. Then, we manipulated Hounsfield units (HU) image data in DICOM (digital imaging and communications in medicine) files di­rectly using our program. The volume and surface area of MACS were computed and compared at segmentation thresholds (HU) from –700 to 0 at intervals of 50 using 2 algorithms; square pixel based (SP) algorithm and march­ing square (MS) algorithm. Results. No significant difference was found between the volumes computed by SP and MS algorithms at each segmenta­tion threshold. The surface area computed by SP algorithm, however, was significantly larger than that by MS algo­rithm. We could minimize this significant difference through a modification of the SP algorithm. As the lower HU threshold value was set, the smaller volume was measured. The surface area showed a plateau at a threshold of ap­proximately –200 HU. The segmentation threshold had greater influence on the measured volume of MACS than the algorithm did. Conclusion. A standard method for measuring volume and surface area of MACS is thought to be necessary. We suggest that the MS algorithm and –200 HU of the threshold could be a standard in the measurement of volume and surface area of MACS.

Original languageEnglish
Pages (from-to)27-32
Number of pages6
JournalClinical and Experimental Otorhinolaryngology
Issue number1
StatePublished - Mar 2016

Bibliographical note

Publisher Copyright:
© 2016 by Korean Society of Otorhinolaryngology-Head and Neck Surgery.


  • Algorithms
  • Computed-assisted
  • Image processing
  • Mastoid
  • Organ size
  • Temporal bone


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