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Proceedings Paper

Performance study of a globally elastic locally rigid matching algorithm for follow-up chest CT
Author(s): Rafael Wiemker; Bartjan de Hoop; Sven Kabus; Hester Gietema; Roland Opfer; Ekta Dharaiya
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Paper Abstract

A real-time matching algorithm for follow-up chest CT scans can significantly reduce the workload on radiologists by automatically finding the corresponding location in the first or second scan, respectively. The objective of this study was to assess the accuracy of a fast and versatile single-point registration algorithm for thoracic CT scans. The matching algorithm is based on automatic lung segmentations in both CT scans, individually for left and right lung. Whenever the user clicks on an arbitrary structure in the lung, the coarse position of the corresponding point in the other scan is identified by comparing the volume percentiles of the lungs. Then the position is refined by optimizing the gray value cross-correlation of a local volume of interest. The algorithm is able to register any structure in or near the lungs, but is of clinical interest in particular with respect to lung nodules and airways. For validation, CT scan pairs were used in which the patients were scanned twice in one session, using low-dose non-contrast-enhanced chest CT scans (0.75 mm collimation). Between these scans, patients got off and on the table to simulate a follow-up scan. 291 nodules were evaluated. Average nodule diameter was 9.5 mm (range 2.9 - 74.1 mm). Automatic registration succeeded in 95.2% of all cases (277 / 291). In successful registered nodules, average registration consistency was 1.1 mm. The real-time matching proved to be an accurate and useful tool for radiologists evaluating follow-up chest CT scans to assess possible nodule growth.

Paper Details

Date Published: 24 March 2008
PDF: 10 pages
Proc. SPIE 6917, Medical Imaging 2008: Image Perception, Observer Performance, and Technology Assessment, 691706 (24 March 2008); doi: 10.1117/12.765166
Show Author Affiliations
Rafael Wiemker, Philips Research Europe (Germany)
Bartjan de Hoop, Univ. Medical Ctr. Utrecht (Netherlands)
Sven Kabus, Philips Research Europe (Germany)
Hester Gietema, Univ. Medical Ctr. Utrecht (Netherlands)
Roland Opfer, Philips Research Europe (Germany)
Ekta Dharaiya, Philips Medical Systems CT (United States)


Published in SPIE Proceedings Vol. 6917:
Medical Imaging 2008: Image Perception, Observer Performance, and Technology Assessment
Berkman Sahiner; David J. Manning, Editor(s)

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