Three-dimensional analysis of pulmonary nodules by MSCT with Advanced Lung Analysis (ALA1) software.

PURPOSE: The purpose of this study was to test the reproducibility of the three-dimensional (3D) Advanced Lung Analysis software (3D-ALA, GE Healthcare) in the estimation of pulmonary nodule volume.
MATERIALS AND METHODS: We retrospectively reviewed the unenhanced multislice CT scans (Lightspeed Pro 16 GE) of 77 patients with a solitary pulmonary nodule (n=71) or metastatic pulmonary disease (n=6). A total of 103 pulmonary nodules (19 well-circumscribed, 45 juxtavascular and 39 juxtapleural) were analysed grouped into five classes based on diameter: <5 mm, 10 nodules (9.7%); >or=5 to <10 mm, 25 nodules (24.2%); >or=10 mm to <15 mm, 41 nodules (39.8%); >or=5 to <18 mm, 14 nodules (13.6% ); >or=8 to <30 mm, 13 nodules (12.62%). The following acquisition parameters were used: slice thickness 0.625 mm, reconstruction interval 0.4 mm, pitch 0.562:1, 140 kV, 300 mAs, field of view 13 cm, bone kernel. For each of the 103 nodules three, 3D volume measurements were obtained by the 3D-ALA software. The reproducibility of nodule segmentation was evaluated according to a visual score (1=optimal, >or=95%; 2=fair, 90-95%; 3=poor, <or=90%) by three observers working in consensus. The reproducibility of volume estimation was evaluated by comparing all 3D volume measurements and all segmentations obtained for each pulmonary nodule using the ANOVA test.
RESULTS: ALA-1 software allowed segmentation in all nodules (type 1 segmentation n=43, type 2 n=35, type 3 segmentation n=25). ALA-1 provided an identical 3D volume measurement in 62 nodules: [16 out of 19 well circumscribed (84.2%), 31 out of 45 juxtavascular (68.8%), 15 out of 39 juxtapleural (38.4%)]. Repeatability of 3D volume measurement was not possible in 41 out of 103 nodules [3 out of 19 (15.7%) well-circumscribed, 14 out of 45 (31.1%) juxtavascular, 24 out of 39 (61.5%) juxtapleural]. Among the 41 nodules with nonrepeatable 3D volume measurement, segmentation was scored as 1 in 2 out of 41 (4.8%), as 2 in 15 out of 41 (36.5%) and as 3 in 24 out of 41 (58.5%). The difference between the mean volume on three measurements and each type of nodule was not statistically significant (p>0.05).
CONCLUSIONS: Three-dimensional volume measurement with ALARiassunto 1 software is reproducible for all nodules as regards dimension and site. ALA-1 software provided a good and reproducible volume measurement in well-circumscribed and most juxtavascular nodules. Volumetric evaluation and reproducibility of volume estimation in juxtapleural pulmonary nodules, particularly those adjacent to diaphragmatic pleura, is inadequate, and software improvement is needed.