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Proceedings Paper

Enhancement measurement of pulmonary nodules with multirow detector CT: precision assessment of a 3D algorithm compared to the standard procedure
Author(s): Dag Wormanns; Ernst Klotz; Gerhard Kohl; Uwe Dregger; Stefan Diederich; Roman Fischbach; Walter Heindel
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Paper Abstract

Precise density measurement of pulmonary nodules with CT is an important prerequisite if the measurement of contrastenhancement is to be used to assess if a nodule is benign or malignant. The precision of a volume-based 3D measurement method was compared to the standard 2D method currently used in clinical practice. Two consecutive low-dose CT scans (inter-scan delay a few minutes) were obtained from 10 patients with 75 pulmonary nodules (size 5 - 32 mm). A four-slice CT was used (Siemens Somatom VZ, collimation 4 x 1 mm, normalized pitch 1.75, slice thickness 1.25 mm, reconstruction interval 0.8 mm). Mean density of each nodule was determined independently from both scans with two methods: 1) an automatic 3D segmentation method; 2) the standard 2D method as proposed in the literature and currently used in clinical practice, (3 mm slice thickness, oval region of interest). ROC analysis was used to compare these methods for the detection of an enhancement of 10, 30 and 50 Hounsfield units (HU). The mean absolute measurement error (± standard deviation) was 9.9 HU (±14.4 HU) for the 3D method and 26.4 HU (±42.0 HU) for the 2D method. ROC analysis yielded AZ values of 0.723 / 0.932 / 0.982 for the 3D method and 0.609 /0.773 / 0.850 for the 2D method for the detection of 10 / 30 / 50 HU enhancement respectively. Volume-based density determination has a significantly higher reproducibility than the currently used 2D ROI approach and should preferentially be used for enhancement measurements in pulmonary nodules.

Paper Details

Date Published: 15 May 2003
PDF: 7 pages
Proc. SPIE 5032, Medical Imaging 2003: Image Processing, (15 May 2003); doi: 10.1117/12.480156
Show Author Affiliations
Dag Wormanns, Univ. of Munster (Germany)
Ernst Klotz, Siemens Medical Solutions (Germany)
Gerhard Kohl, Siemens Medical Solutions (Germany)
Uwe Dregger, Univ. of Munster (Germany)
Stefan Diederich, Univ. of Munster (Germany)
Roman Fischbach, Univ. of Munster (Germany)
Walter Heindel, Univ. of Munster (Germany)

Published in SPIE Proceedings Vol. 5032:
Medical Imaging 2003: Image Processing
Milan Sonka; J. Michael Fitzpatrick, Editor(s)

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