HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Tsao, J. Articles by Ichise, M. Search for Related Content PubMed PubMed Citation Articles by Tsao, J. Articles by Ichise, M.

Fully Automated Establishment of Stereotaxic Image Orientation in Six Degrees of Freedom for Technetium-99m-ECD Brain SPECT

Department of Nuclear Medicine, Mount Sinai Hospital, and University of Toronto, Toronto, Ontario;, Canada

Correspondence: For correspondence or reprints contact: Masanori Ichise, MD, FRCP(C), Nuclear Medicine, Room 635, Department of Medical Imaging, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada M5G 1X5.

ABSTRACT

Anatomical localization requires establishing an anatomical space within the image matrix. We developed a fast, fully automated method to establish the image orientation for ^99mTc-ethylcysteinate dimer (ECD) brain SPECT images. Methods: The image orientation of ECD brain SPECT images was established in four stages. First, the brain surface was edge-detected as an isosurface at an adaptive threshold. Second, a "convex hull" was determined for the isosurface to minimize regional variability in brain shape. A principal axis transformation and a symmetry vector analysis were applied to the convex hull to resolve the craniocaudal direction and to estimate the midsagittal plane. Third, the brain orientation was refined from this estimate by location of the interhemispheric fissure, the tentorial groove and the frontotemporal groove on the isosurface. Last, the intercommissural (anterior commissure-posterior commissure, or AC–PC) line was detected on the midsagittal slice, and the Talairach grid was scaled to fit the maximal brain dimensions from the AC–PC line. Results: The average absolute errors were 2.3° ± 1.5° and 1.08 mm ± 1.11 mm for the midsagittal plane (n = 24) and 2.04° ± 0.80°, 2.0% ± 1.8% of the brain length and 2.3% ± 2.2% of the brain height for the AC–PC line (n = 8). In addition, this program successfully established the image orientation in 94 of 100 clinical ECD brain SPECT studies. Processing time was <40 sec for 128 x 128 x 50 matrices on a DEC Alpha workstation. Conclusion: We have developed a fast, robust and fully automated method that determines the orientation of ECD brain SPECT images. This objective method of standardizing the image orientation should be useful for anatomical localization and clinical interpretation of these images.

Key Words: technetium-99m-ECD • brain SPECT • image orientation • automation • image processing