CT-based weight assessment of lung lobes: comparison with ex vivo measurements

Abstract

ORIGINAL ARTICLE PURPOSE We aimed to evaluate the validity of lung lobe weight assessment via computed tomography (CT) by comparing CT-derived and ex vivo measurements. MATERIALS AND METHODSUnenhanced CT scanning was performed in 30 consecutive patients before lobectomy for lung cancer. The CT images were analyzed using research software after allowing for lobar weight quantitation. The lobar weight estimated by CT was then compared with that measured after surgery using a precision scale (ex vivo measurement). Comparisons as well as assessment of intra-and interoperator variability were conducted using the Bland-Altman method and the coefficient of repeatability (CR). Correlations were examined using Pearson's correlation analysis. RESULTSComparison analyses were feasible for 28 cases. The ex vivo lobe weight was 186.2±57.3 g, whereas the weights measured by the two operators by CT were 190.0±55 and 182.4±58.2 g, respectively. As compared with ex vivo weights, the CR was 36.4 for operator 1 and 50.4 for operator 2; the mean differences were 3.8 and -3.8 for operators 1 and 2, respectively. The intraoperator and interoperator CR were 20.9 and 36.6, respectively. The mean differences for the intra-and interoperator analysis were -1.5 and -7.5, respectively. The correlation was very high between CT-based and ex vivo measurements (r=0.95 and r=0.90 for operators 1 and 2, respectively; P < 0.001). CONCLUSIONEstimation of lung lobe weight by semi-automated CT analysis is sufficiently reproducible and in agreement with ex vivo measurements. C omputed tomography (CT) is the most widely used imaging modality for the evaluation of lung disease at the lobar level. Several methods for the automatic and semi-automatic segmentation of the lung lobes have been developed (1-5).This advance in postprocessing CT technique also allows lobar assessment of several CT parameters, such as volume, mean density, and emphysema extent. Lobe-specific measurements may provide insight into both underlying disease mechanisms and the spectrum of disease phenotypes (particularly in chronic obstructive lung disease), as well as help to refine therapeutic strategies (4-6). Prior studies also evaluated the reliability of the corresponding measurements by testing the inherent interoperator variability or comparing software results with the visual score (7,8). However, the accuracies of CT-based lobe segmentation and measurements have yet to be proven in comparison with a gold standard, such as pathological measurements.The combination of lung volume and density allows the estimation of other volumetric parameters such as lung weight (9, 10). The lobe weight when assessed by automated CT analysis may be suitable for pathological correlations. Lobe weight measurement, as outlined in the present study, is based on the calculation of lobe density and volume. Lobe volume variation (e.g., due to different levels of inspiration) may be attenuated using the density of the corresponding lung. Therefore, weighing the lungs by CT may be important because suc...

Validation of computed tomography for measuring lung weight

“…Other authors have shown that CT properly quantifies the weight of inanimate objects [ 8 ], artificial lung models [ 13 ], exsanguinated [ 14 ] and frozen [ 15 ] lungs and surgically excised pulmonary lobes [ 16 ]. Results acquired in vivo can be less accurate.…”

Automated Quantitative Lung CT Improves Prognostication in Non-ICU COVID-19 Patients beyond Conventional Biomarkers of Disease

“…The analysis was performed on total volume to avoid partial volume artifact. Calculation of weight of differently aerated areas was made through volumes and mean density (lung weight = lung volume × (mean density + 1000)/1000) [45][46][47].…”

“…with different gas/tissue ratios, which can turn critically in the clinical work-up of a symptomatic COVID-19 patient [39,[45][46][47][48][49][50].…”

“…However, lung tissue weight can be derived from quantitative analysis through volume and mean density assessment, thus allowing a specific differentiation between areas with different gas/tissue ratios, which can turn critically in the clinical work-up of a symptomatic COVID-19 patient [39,[45][46][47][48][49][50].…”

Pulmonary quantitative CT imaging in focal and diffuse disease: current research and clinical applications

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