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. 2022 Mar 20;127(5):543–559. doi: 10.1007/s11547-022-01471-y

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© The Author(s) 2022

Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

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Fig. 5 — A–D. Collateral (smoking-related) findings in screening LDCT. Quantification of pulmonary emphysema with application of the 950HU density mask. Pulmonary emphysema quantified by density mask with segmentation of lung areas with density lower than − 950 HU. The example shows the step-wise process of segmentation of lung parenchyma (A: native image; B: extraction of lung volume) and subsequent quantitation of emphysema extent represented as low attenuation area (LAA) with density below − 950 HU, as represented by green overlay (C). The density histogram (D) shows the distribution of density across the lung volume, and allows to quantify the proportion of LAA below -950 HU as relative extent compared to the overall lung volume (E), namely 11% in this example (specific lobar quantitation is also provided)