Comparison of manual and semi-automated delineation of regions of interest for radioligand PET imaging analysis

Tiffany W Chow¹^,2^,3 , Shinichiro Takeshita⁴ , Kie Honjo⁵ , Christina E Pataky¹ , Peggy L St Jacques⁶ , Maggie L Kusano⁷ , Curtis B Caldwell⁷ , Joel Ramirez⁸ , Sandra Black¹^,8^,9 and Nicolaas PLG Verhoeff³^,5

¹Rotman Research Institute, Baycrest, Toronto, Canada

²Dept. of Medicine, University of Toronto, Toronto, Canada

³Dept. of Psychiatry, University of Toronto, Toronto, Canada

⁴Department of Neurosurgery, Hiroshima Red Cross Hospital & Atomic-bomb Survivors Hospital, Hiroshima, Japan

⁵Kunin-Lunenfeld Applied Research Unit, Baycrest, Toronto, Canada

⁶Dept. of Psychology, Duke University, Durham, USA

⁷Departments of Medical Imaging and Medical Biophysics, Department of Medical Physics, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, Canada

⁸Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Canada

⁹Cognitive Neurology Research Unit, Sunnybrook Health Sciences Centre, Toronto, Canada

author email corresponding author email

BMC Nuclear Medicine 2007, 7:2doi:10.1186/1471-2385-7-2


Published:	29 January 2007

Abstract

Background

As imaging centers produce higher resolution research scans, the number of man-hours required to process regional data has become a major concern. Comparison of automated vs. manual methodology has not been reported for functional imaging. We explored validation of using automation to delineate regions of interest on positron emission tomography (PET) scans. The purpose of this study was to ascertain improvements in image processing time and reproducibility of a semi-automated brain region extraction (SABRE) method over manual delineation of regions of interest (ROIs).

Methods

We compared 2 sets of partial volume corrected serotonin 1a receptor binding potentials (BPs) resulting from manual vs. semi-automated methods. BPs were obtained from subjects meeting consensus criteria for frontotemporal degeneration and from age- and gender-matched healthy controls. Two trained raters provided each set of data to conduct comparisons of inter-rater mean image processing time, rank order of BPs for 9 PET scans, intra- and inter-rater intraclass correlation coefficients (ICC), repeatability coefficients (RC), percentages of the average parameter value (RM%), and effect sizes of either method.

Results

SABRE saved approximately 3 hours of processing time per PET subject over manual delineation (p < .001). Quality of the SABRE BP results was preserved relative to the rank order of subjects by manual methods. Intra- and inter-rater ICC were high (>0.8) for both methods. RC and RM% were lower for the manual method across all ROIs, indicating less intra-rater variance across PET subjects' BPs.

Conclusion

SABRE demonstrated significant time savings and no significant difference in reproducibility over manual methods, justifying the use of SABRE in serotonin 1a receptor radioligand PET imaging analysis. This implies that semi-automated ROI delineation is a valid methodology for future PET imaging analysis.