Improvement in the reproducibility of MDCT quantification of lobar pulmonary volumes using an automatic segmentation technique

Purpose: Density-based MDCT quantification (q-MDCT) of lung volumes is relevant in patients with emphysema or lung cancer. The inter- and intra-operator variabilities of q-MDCT obtained by two segmentation techniques were compared. Methods and Materials: Forty-seven chest MDCT examinations of patients with emphysema (men/women = 34/13, age range: 48-85) were selected from our database. All patients had been studied with lung function tests and a standardized imaging protocol on a 16-MDCT scanner (thickness/interval=1.25 mm; pitch=1.5). The MDCT datasets were analyzed independently by two operators using a manual procedure for delimitation of pulmonary lobes (A), and a full-automatic approach that allowed for manual refinement of lobar separation (B). Lung (V) and emphysema volumes (VE) were obtained from both lungs and each lobe. The inter- and intra-operator differences were expressed as percentages over means. Mean differences (Δ-tot) and standard deviations (SD-tot) calculated from the two approaches were compared. Results: The analysis conducted for both lungs showed minimal variability using A and no variability using B. From the lobar analysis, inter- and intra-operator variability ranges (min/max) obtained from B were lower than those from A: for V (B vs. A: Δinter-tot ± SDΔinter-tot = -3.7/1.6 ± 4/17% vs. -3.9/3.5 ± 4.5/22.6%;Δintra-tot ± SDΔintra-tot = 0.6/0.4 ± 1.3/8.1% vs. -1.5/0.9 ± 2.5/10.6%); for VE (B vs. A: Δinter-tot ± SDΔinter-tot = -3/2.9 ± 5/18.9% vs. -3/2.9 ± 8.5/23.3%; Δintratot± SDΔintra-tot = -0.5/0. ± 3.2/9.8% vs. -1.1/1 ± 5.6/13.7%). Conclusion: The reproducibility of q-MDCT lobar volumetry is improved by using an automatic segmentation technique.