Comparison of distinctive models for calculating an interlobar emphysema heterogeneity index in patients prior to endoscopic lung volume reduction

The impact of emphysema heterogeneity on treatment response after endobronchial valve treatment

Background

Lung volume reduction with endobronchial valves can significantly improve functional outcomes in patients with advanced emphysema. The extent and spatial distribution pattern of emphysema shows considerable heterogeneity, which might affect response to endobronchial valve treatment. Our aim was to study the effect of emphysema heterogeneity on change in clinical outcomes after endobronchial valve treatment.

Methods

Data were collected from our national registry of patients who received endobronchial valve treatment between 2016 and 2020. We assessed the association between the heterogeneity index, absolute difference in destruction between the target and ipsilateral lobe, and relative change in forced expiratory volume in 1 s (FEV1), residual volume (RV), St George's Respiratory Questionnaire (SGRQ) and 6-min walk distance (6MWD) at 6-week, 6-month and 12-month follow-up.

Results

In total, 236 patients were included. Heterogeneity index was significantly associated with improvements in FEV1, RV and 6MWD at all follow-up visits, and in SGRQ at the 6- and 12-month follow-up visits. The majority of patients, independent of heterogeneity index, showed clinically meaningful improvements based on minimal important difference thresholds.

Conclusions

Heterogeneity index influences the degree of clinical improvement after endobronchial valve treatment where in general a more heterogeneous distribution translates to larger improvements. However, patients with a more homogeneous distribution also showed clinically meaningful improvements. Therefore, we believe emphysema heterogeneity alone should not be used as a decisive patient selection criterion, but should be weighed in the context of all other relevant patient and target lobe characteristics when deciding on a patient's treatment eligibility.

[Computed tomographic imaging in chronic obstructive pulmonary disease : What pulmonologists and thoracic surgeons want to know]

Chronic obstructive pulmonary disease (COPD) begins with chronic inflammation of the bronchial system and leads to the development of emphysema in many patients. COPD patients are characterized by reduced performance, dyspnea in the context of an obstructive respiratory disorder and increased susceptibility to infections. COPD has a major impact on public health, as it is very common and many patients die from it. The most important preventable cause of COPD is tobacco smoke inhalation, which is why consistent smoking cessation is the most important component of any COPD treatment. There is no causal therapy, but in severely symptomatic patients with advanced emphysema, respiratory mechanics can be improved by lung volume reduction if all conservative treatment options have been exhausted. Diagnostic imaging is of great importance in the care of COPD patients. This article summarizes which indications warrant the performance of computed tomography (CT) and what we should pay special attention to during image analysis in order to provide optimal advice to our clinical partners.

Prediction of response to endobronchial coiling based on morphologic emphysema characterization of the lung lobe to be treated and the ipsilateral non-treated lobe as well as on functional computed tomography-data: correlation with clinical and pulmonary function

Background

To test if the emphysema type of the targeted lobe, ipsilateral non-targeted lobe, and lobes of the contralateral lung impact outcome of endobronchial lung volume reduction (ELVR) treatment, and to document lobar volume changes in treated and non-treated lung lobes.

Methods

Thirty patients (16 men, 14 women; median age, 66±6 years; range, 48-78 years) underwent chest-computed tomography (CT) before and after endobronchial coiling for lung volume reduction (LVR) at our institution between December 2011 and March 2016. Forty-five pulmonary lobes were coiled. We classified the treated lobes into homogenous or heterogeneous emphysema phenotype based on the distribution of voxels showing tissue attenuation of less than -950 HU. Clinical response was defined as an increase or consistency in the walking distance (6MWT) 6 months after LVR-therapy. Lung volume changes were compared for treated, ipsilateral, and contralateral lobes. Additionally, pulmonary function tests (PFT), chronic obstructive pulmonary disease (COPD) assessment test (CAT), and blood gas analysis were performed.

Results

Responder (19/30, 63.3%) showed a significant improvement of 6 MWT from 281.05 to 335.26 (P=0.001). Non-responder (11/30, 36.7%) showed a decrease in 6MWT from 308.18 to 255.45 (P=0.001). Responders showed a significant reduction in CAT test from 23.23 to 20.73 points (P=0.038) and pCO₂ from 42.94 to 40.31 (P=0.001), whereas non-responders showed an increase in pCO₂ (P=0.003; from 44.27 to 47.45). There were no significant changes in PFT-parameters. In responders, there was a significant volume reduction in treated lobes from 1,627.68 to 1,519.21 mL (P=0.009). In responders, treated lobes/non-treated ipsilateral lobes were homogenous (n=11/5) and heterogeneous (n=10/28). In non-responders, treated lobes/non-treated ipsilateral were homogenous (n=5/4) and heterogeneous (n=7/16). In responders and non-responders, the emphysema phenotype in treated, ipsilateral non-treated and even contralateral lobes (P=0.250) did not differ and or change significantly before and after therapy. Only the volume of treated lobes in responders changed significantly after coiling.

Conclusions

The emphysema-phenotype in the targeted and non-targeted ipsilateral lobe has no impact on the outcome of endobronchial coiling for LVR and also does not change significantly after treatment, whereas the volume of the treated lobe significantly decreases in responders.

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

The frenetic development of imaging technology-both hardware and software-provides exceptional potential for investigation of the lung. In the last two decades, CT was exploited for detailed characterization of pulmonary structures and description of respiratory disease. The introduction of volumetric acquisition allowed increasingly sophisticated analysis of CT data by means of computerized algorithm, namely quantitative CT (QCT). Hundreds of thousands of CTs have been analysed for characterization of focal and diffuse disease of the lung. Several QCT metrics were developed and tested against clinical, functional and prognostic descriptors. Computer-aided detection of nodules, textural analysis of focal lesions, densitometric analysis and airway segmentation in obstructive pulmonary disease and textural analysis in interstitial lung disease are the major chapters of this discipline. The validation of QCT metrics for specific clinical and investigational needs prompted the translation of such metrics from research field to patient care. The present review summarizes the state of the art of QCT in both focal and diffuse lung disease, including a dedicated discussion about application of QCT metrics as parameters for clinical care and outcomes in clinical trials.