A method for the automatic quantification of the completeness of pulmonary fissures: evaluation in a database of subjects with severe emphysema

Abstract

ObjectivesTo propose and evaluate a technique for automatic quantification of fissural completeness from chest computed tomography (CT) in a database of subjects with severe emphysema.MethodsNinety-six CT studies of patients with severe emphysema were included. The lungs, fissures and lobes were automatically segmented. The completeness of the fissures was calculated as the percentage of the lobar border defined by a fissure. The completeness score of the automatic method was compared with a visual consensus read by three radiologists using boxplots, rank sum tests and ROC analysis.ResultsThe consensus read found 49% (47/96), 15% (14/96) and 67% (64/96) of the right major, right minor and left major fissures to be complete. For all fissures visually assessed as being complete the automatic method resulted in significantly higher completeness scores (mean 92.78%) than for those assessed as being partial or absent (mean 77.16%; all p values <0.001). The areas under the curves for the automatic fissural completeness were 0.88, 0.91 and 0.83 for the right major, right minor and left major fissures respectively.ConclusionsAn automatic method is able to quantify fissural completeness in a cohort of subjects with severe emphysema consistent with a visual consensus read of three radiologists.Key Points• Lobar fissures are important for assessing the extent and distribution of lung disease• Modern CT allows automatic lobar segmentation and assessment of the fissures• This segmentation can also assess the completeness of the fissures.• Such assessment is important for decisions about novel therapies (eg for emphysema).

Status of and prospects for bronchoscopic lung volume reduction for patients with severe emphysema

“…The assessments are heavily influenced by the level of experience of the experts and they are highly subjective, and often there is disagreement between imaging experts (32). With the development of computer technology, automated analysis can improve the efficiency and accuracy of inspections of the interlobular fissure, but it still cannot replace the role of imaging experts (33,34). In the BeLieVeR-HIFi study, 4 patients with a complete interlobular fissure according to imaging experts failed to benefit from EBV implantation (31).…”

Emphysema: Imaging for Endoscopic Lung Volume Reduction

“…As a result, the reported occurrence of incomplete fissures greatly fluctuates in the literature between 20 % and 87 %. Automatic fissure analysis methods are currently being developed [55].…”

Lung Volume Reduction in Pulmonary Emphysema from the Radiologist’s Perspective

“…The large contrast in density between the blood vessels and the air-filled lung parenchyma means that the automated segmentation of the major vessels is usually sufficient [38]. In their current article examining 96 patients with emphysema, Van Rikxoort et al compare the results of automated segmentation of fissures performed by modern software versus a visual consensus read performed by three experienced radiologists, likewise finding acceptable agreement [43]. Nevertheless, most published studies employ visual inspections and, if applicable, interactive correction of the contours of the fissures proposed by the software.…”

“…The analytic methods common today are mostly threshold value-based, i. e. all voxels below a threshold value are viewed as emphysematous lung parenchyma [42]. The specific threshold value of the emphysema, i. e. that value at which the volumes with lower CT density than emphysematous lung tissue are defined, is primarily set between -910 HU [43] and -950 HU [44]. The so-called pixel index is defined as the portion in percent (%) that the voxels below the threshold value constitute of the voxels of the entire pulmonary volume and is also referred to as "emphysema score" when used to emphysema.…”

“…The occurrence of incomplete fissures (IF) was first described in the 1940 s [60]. In recent years, numerous studies concerning modern ELVR methods have led to a better functional understanding of this frequent anatomic variant [43]. Aziz et al conducted a visual CT analysis of the completeness of fissures in 622 healthy patients, finding IF in 43 % of left fissures, 48 % of major right fissures and 63 % of minor right fissures [61].…”