QUANTITATIVE-ANALYSIS OF COMPUTED-TOMOGRAPHY SCANS OF THE LUNGS FOR THE DIAGNOSIS OF PULMONARY-EMPHYSEMA - VALIDATION-STUDY OF A SEMIAUTOMATED CONTOUR-DETECTION TECHNIQUE
R. Zagers et al., QUANTITATIVE-ANALYSIS OF COMPUTED-TOMOGRAPHY SCANS OF THE LUNGS FOR THE DIAGNOSIS OF PULMONARY-EMPHYSEMA - VALIDATION-STUDY OF A SEMIAUTOMATED CONTOUR-DETECTION TECHNIQUE, Investigative radiology, 30(9), 1995, pp. 552-562
RATIONALE AND OBJECTIVES. TO develop an analytic software package base
d on automated contour detection for the objective and reproducible as
sessment of emphysema from computed tomography (CT) scans. METHODS. A
semiautomated technique was developed for the definition of lung conto
urs in CT cross-sections followed by the assessment of pulmonary CT pa
rameters describing the disease state, For 78 images, the semiautomate
d contour detection was performed and compared with contours drawn by
an experienced radiologist by calculating the systematic area differen
ce (bias) and differences in pulmonary CT parameters such as the mean
lung density (MLD). In addition, intraobserver and interobserver varia
bilities were determined in a subset of 15 images. RESULTS. The areas
enclosed by the semiautomatically detected contours were slightly larg
er than the manual ones (bias < 2.1%). The biases in the observer stud
ies were smaller in the semiautomated versus the manual case (0.3% vs.
1.3%). The standard deviation of the MLD differences with a manual an
alysis was larger by a factor of five than in the semiautomated case,
On average, manual analysis required 2 minutes, 18 seconds per lung; t
his time was reduced to 11.5 to 29 seconds with the semiautomated appr
oach, depending on the respiration state. CONCLUSIONS. The semiautomat
ed approach is preferred over the manual approach because of its highe
r consistency and its shorter analysis time.