Isam Albaba, MBSS, from the department of thoracic medicine & surgery at Temple University Hospital.

Isam Albaba, MBBS

CT Air Trapping Metric May Predict Post-BLVR Pneumothorax Risk

Functional air trapping measured specifically within emphysematous regions of the lung, rather than across the whole lobe, may offer a meaningful pre-procedural signal for pneumothorax risk following bronchoscopic lung volume reduction (BLVR) in patients with 

chronic obstructive pulmonary disease (COPD)

, according to research presented at the 

American Thoracic Society (ATS) 2026 International Conference

The retrospective analysis, presented by Isam Albaba, MBBS, from Temple University, examined quantitative CT (QCT) parameters in 59 patients who underwent BLVR, 27 of whom developed post-procedure pneumothorax and 32 of whom did not. Using Coreline software to analyze paired inspiratory and expiratory CT scans, investigators evaluated a range of metrics, including lobar volumes, fissure completeness, change in mean lung density, and functional air trapping (fAT), defined as the proportion of lung voxels demonstrating air retention between the 2 scans.

Among all evaluated parameters, functional air trapping specifically within emphysematous lung regions (fAT-E) emerged as the strongest predictor of post-BLVR pneumothorax. In the full cohort, fAT-E reached statistical significance 

 =.017), with ROC curve analysis identifying an optimal threshold of approximately 25% (AUC 0.68; 67% sensitivity, 75% specificity). Total fAT across the whole lobe did not reach significance.

, Albaba noted that the analysis evolved after the abstract was submitted.

 Restricting the fAT-E analysis to higher-quality scans, defined as those with at least a one-liter volume change between inspiration and expiration, strengthened the signal considerably (

 =.002; AUC 0.79), with specificity rising to 94% at a threshold of approximately 26.5%.

"When we applied the functional air trapping just in the emphysema areas, not in the whole lung, not in the whole lobe, we found a very statistically significant prediction of pneumothorax," Albaba said.

Many BLVR candidates have 2 viable target lobes, with decisions currently informed by tools such as VQ scanning to assess relative perfusion. A validated fAT-based metric could add another dimension to that calculus—one oriented specifically around pneumothorax risk.

"If I target this lobe, is the chance of pneumothorax happening 50% as opposed to the other one, where there's 10%? That will probably take me more towards the latter target because there's less likelihood of pneumothorax happening, but I will still be able to get the same benefits of the volume reduction and the improvement in quality of life," Albaba said.

Beyond target selection, Albaba outlined a longer-term research question: whether very high fAT in emphysematous areas might predict persistent air leak, which is a more serious and less common outcome than pneumothorax itself. While most post-BLVR pneumothoraces resolve with chest tube drainage and patients are discharged without recurrence, a subset requires prolonged drainage, ultimately necessitating valve removal and forfeiture of procedure benefit. Identifying those patients before the procedure could inform patient selection decisions.

"Trying to identify patients using that metric…could be a future direction," Albaba said. "If somebody has very high functional air trapping in emphysematous areas, that may actually put them out of the [running for] this procedure, and maybe just look at other things that we can do for our COPD patients."

On the question of real-world accessibility, Albaba acknowledged that quantitative CT analysis software, including Coreline, remains unavailable at many institutions, though adoption is growing. He framed prospective validation as the prerequisite for broader clinical uptake.

"We will be able to prospectively validate, but we have to do that first before we can say that we can now just basically make it a standard of care or make it an available tool for physicians to use to predict pneumothorax before the procedure even happens," Albaba said.

Editor’s note: Albaba has no reported disclosures.

) Quantitative CT Predictors of Pneumothorax After Bronchoscopic Lung Volume Reduction: The Role of Air Trapping and Lobar Volume Interactions. Poster presented at: American Thoracic Society (ATS) International Conference 2026 on May 19 in Orlando, Florida

Albaba I, Deller E, Lalwani A, Dachert S, Criner G. Functional air trapping predicts pneumothorax after BLVR. Poster presented at American Thoracic Society International Conference 2026; May 16 –21; Orlando, FL. Poster P354.

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Functional air trapping in emphysematous lung regions may predict pneumothorax after BLVR, per ATS 2026 data presented by Isam Albaba, MBBS, from Temple University.


Higher-Resolution CT May Predict Pneumothorax After BLVR, With Isam Albaba, MBBS

2026 American Thoracic Society (ATS) International Conference 

in Orlando, Florida, Isam Albaba, MBSS, from the department of thoracic medicine & surgery at Temple University Hospital, discussed how functional air trapping on CT imaging may help identify patients at the greatest risk for pneumothorax following bronchoscopic lung volume reduction (BLVR).

BLVR is increasingly used in select patients with severe 

, particularly those with advanced emphysema. Pneumothorax remains the most frequent complication and can lead to prolonged hospitalization, chest tube placement, and, in severe cases, valve removal.

The study presented at ATS evaluated whether pre-procedural CT imaging could better stratify risk than traditional selection measures such as fissure integrity alone. Investigators focused on functional air trapping within the ipsilateral non-target lobe, using advanced quantitative CT techniques.

“Fissure integrity is a starting point,” Albaba said. “If they do not have fissure integrity, they are not eligible for BLVR. [It] doesn't necessarily determine [if] pneumothorax [will happen].”

Some studies have suggested that greater fissure completeness and integrity may be associated with a greater likelihood of pneumothorax, which is physiologically plausible since more complete fissures allow greater volume redistribution to the ipsilateral lobe. However, on their own, these measures are not strong or reliable predictors of pneumothorax development.

“It's not just about how much volume goes into the ipsilateral,” he said. “It's also about how fragile that tissue is and how much air trappings [is] happening in the fragile lung, as opposed to areas that are not as fragile and likely to have a defect in the pleural space that will…result in a pneumothorax.”

The analysis found that functional air trapping specifically within emphysematous regions of the lung (fAT-E) was the strongest predictor of pneumothorax risk. Static CT measures alone were not sufficient, underscoring the importance of dynamic physiologic imaging.

A threshold of approximately 25% to 27% functional air trapping provided the best discrimination between patients who did and did not develop pneumothorax, with greater specificity in refined analyses (94% vs 75%).

Albaba noted that scan quality itself plays an important role in interpretation. The data becomes less reliable if a patient does not achieve adequate inspiratory and expiratory volumes. For instance, a change of ≥ 1 liter between scans significantly improves the accuracy of functional air trapping measurements.

The findings suggest that incorporating quantitative CT metrics into pre-procedure planning could help clinicians better anticipate complications and potentially refine post-BLVR monitoring strategies. Currently, many patients are routinely hospitalized for observation after valve placement due to pneumothorax risk, contributing to substantial healthcare utilization.

Future research will focus on validating these imaging biomarkers across larger cohorts and integrating them into prospective BLVR planning algorithms to better personalize procedural risk assessment.

Albaba I, Deller E, Lalwani A, et al. Functional Air Trapping Predicts Pneumothorax After BLVR. Poster presented at ATS 2026 in Orlando, Florida, on May 19.

A quantitative CT-based approach may help predict pneumothorax risk after bronchoscopic lung volume reduction, according to findings presented at ATS 2026.

Isam Albaba, MBBS

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