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. 2026 Jan 12:thorax-2025-223755.
doi: 10.1136/thorax-2025-223755. Online ahead of print.

Elastic parametric response mapping: quantitative CT scoring for local COPD severity

Wassim W Labaki  1 , Sundaresh Ram  2 , Ali Namvar  3 , Alexander J Bell  3 , Benjamin A Hoff  3 , Ella A Kazerooni  3 , Stefanie Galban  3 , Fernando J Martinez  4 , Charles R Hatt  5 , Susan Murray  6 , Evgeny M Mirkes  7 , Alexander N Gorban  7 , Andrei Zinovyev  8 , MeiLan K Han  1 , Craig J Galban  9
Affiliations

Elastic parametric response mapping: quantitative CT scoring for local COPD severity

Wassim W Labaki et al. Thorax. .

Abstract

Background: Current quantitative chest CT techniques improve chronic obstructive pulmonary disease (COPD) phenotyping but do not capture spatial variability and potentially reversible disease in local lung parenchyma.

Methods: Applying elastic principal graphing to CT scans from Genetic Epidemiology of COPD study participants (age 45-80 years; ≥10 pack-years), we developed elastic parametric response mapping (ePRM), a tiered scoring system (tiers 0-3 and tier Op, ie, lung opacities) that classifies lung subvolumes based on their relative composition of normal lung, emphysema, small airways disease and parenchymal disease. For 3631 participants with longitudinal data, we evaluated how relative tier assignment and mean tier position of subvolumes changed over 5 years and how they associated with forced expiratory volume in 1 s (FEV1) change. We stratified analyses by baseline spirometry: no airflow obstruction, Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1-2 and GOLD 3-4.

Results: The proportion of tier 0 subvolumes decreased with worsening airflow obstruction, while tier 2 and 3 proportions increased. Tier 1 proportions were similar in GOLD 1-2 (25.7%) and GOLD 3-4 (28.1%), with over half of subvolumes remaining in tier 1 or reverting to tier 0 at year 5. In contrast to tiers 0 and 2, baseline mean tier 1 position was strongly predictive of reassignment to more advanced tiers at year 5 in participants without airflow obstruction, GOLD 1-2 and GOLD 3-4 (area under the curves (95% CIs) 0.86 (0.85 to 0.87), 0.90 (0.89 to 0.91) and 0.92 (0.90 to 0.93), respectively). A higher per cent volume of lung retained in tier 1 was associated with less FEV1 decline in all groups.

Conclusion: CT ePRM categorises local lung tissue into distinct and potentially reversible tiers of disease severity.

Keywords: Emphysema; Imaging/CT MRI etc; Pulmonary Disease, Chronic Obstructive.

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Conflict of interest statement

Competing interests: WWL reports grants from the National Institutes of Health (NIH), consulting fees from Inogen and Verona, and conference attendance/travel support from Inogen. He has served as Executive Secretary on a Data Safety Monitoring Board for a pilot trial of aspirin in COPD conducted at Johns Hopkins University. FJM reports support for the parent study analysed in this manuscript from the National Heart, Lung and Blood Institute (NHLBI) of NIH; grant support from AstraZeneca and GSK, which are partners in the SPIROMICS programme and NHLBI CAPTURE validation study; in-kind grant support from Chiesi and Sanofi/Regeneron, which are partners of the SPIROMICS programme; payments made to the COPD Foundation for partnership in SPIROMICS and/or CAPTURE from NHLBI, AstraZeneca, Chiesi, Boehringer Ingelheim, GlaxoSmithKline, Novartis and Sanofi/Regeneron; consulting fees and travel support from AstraZeneca and GSK, which are partners of the SPIROMICS programme and in the NHLBI CAPTURE validation study; travel support from Chiesi for service on the COPD Steering Committee and Global Advisory Board; consulting fees for service on the COPD Steering Committee and Advisory Board from Sanofi/Regeneron, which are partners of the SPIROMICS programme; payment or honouraria for COPD CME from UpToDate; and consulting fees for service on the COPD Steering Committee and medical writing support from Novartis, which is a partner of the SPIROMICS programme. He has served on the COPD Steering Committee without fees for DevPro and provided unpaid consultation on COPD to Roche. He has received payment or honouraria for disease state presentations from Roche and from AstraZeneca and GSK, which are partners of the SPIROMICS programme and the NHLBI CAPTURE validation study. He has participated in an event adjudication committee for MedTronic. CRH reports stock options with and employment by 4D Medical USA. SM reports grant support from NIH. MKH reports grants or contracts from NIH, Sanofi, Novartis, Nuvaira, Sunovion, Gala Therapeutics, the COPD Foundation, AstraZeneca, the American Lung Association (ALA), Boehringer Ingelheim, Biodesix and Regeneron; royalties or licences from UpToDate, Norton Publishing and Penguin Random House; consulting fees from AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, Pulmonx, Teva, Verona, Merck, Mylan, Sanofi, DevPro, Aerogen, Polarian, Regeneron, Altesa Biosciences, Amgen, Roche, RS Biotherapeutics, Apreo Health, Genentech, Owkin, Bristol Myers Squibb and Zymeworks; and payments or honouraria from Cipla, Chiesi, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Medscape, Integrity, NACE and Medwiz. She has participated in Data Safety Monitoring Boards for Novartis and Medtronic with funds paid to the institution, and served in leadership or fiduciary roles for the COPD Foundation Board, the COPD Foundation Scientific Advisory Committee, the ALA Advisory Committee, the GOLD Scientific Committee, and the Emerson School Board (Ann Arbor, MI). She is a journal editor for the American Thoracic Society and a volunteer spokesperson for ALA. She has received stock options from Meissa Vaccines and Altesa Biosciences. She has received writing support from GSK, Boehringer Ingelheim, AstraZeneca and Novartis. CJG reports grants from NHLBI/NIH. He is co-inventor and patent holder of PRM, which is licensed to 4D Medical by the University of Michigan. SR, AN, AJB, BAH, EAK, SG, EMM, ANG and AZ report no conflicts of interest.

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