Emphysema: Imaging for Endoscopic Lung Volume Reduction

Abstract

!Chronic obstructive pulmonary disease (COPD) is characterized by two entities, the more airway-predominant type ("bronchitis") on the one hand, and emphysema-predominant type on the other. Imaging via high-resolution computed tomography plays an important role in phenotyping COPD. For patients with advanced lung emphysema, new endoscopic lung volume reduction therapies (ELVR) have been developed. Proper selection of suitable patients requires thinsection reconstruction of volumetric CT image data sets also in coronal and sagittal orientation are required. In the current manuscript we will describe emphysema subtypes (centrilobular, paraseptal, panlobular), options for quantifying emphysema and this importance of regional distribution (homogeneous or heterogeneous, target area) as this is crucial for patient selection. Analysis of the interlobular fissures is obligatory despite the lack of standardization, as incomplete fissures indicate collateral ventilation (CV) via parenchymal bridges, which is an important criterion in choosing endoscopic methods of LVR. Every radiologist should be familiar with modern LVR therapies such as valves and coils, and furthermore should know what a lung doctor expects from radiologic evaluation (before and after ELVR). Finally we present a checklist as a quick reference for all steps concerning imaging for ELVR.

Patterns of Emphysema Heterogeneity

“…Each endoscopic LVR technique differs in its mechanistic target and, therefore, safety and efficacy capability. Accordingly, each technique assesses different patient and disease characteristics, such as fissure integrity and collateral ventilation, to determine patient eligibility and LVR technique compatibility [17–21]. Among these patient characteristics, disease heterogeneity is also assessed but, typically, is not evaluated within a lobe.…”

“…There are currently four endoscopic LVR techniques being investigated for patients with emphysema: valves, coils, sealants, and vapor [17–21]. Due to intralobar collateral ventilation, valve LVR technologies are limited to a lobar approach where an entire lobe is targeted during an LVR procedure.…”

Imaging approaches to understand disease complexity: chronic obstructive pulmonary disease as a clinical model

“…Collateral ventilation prevents the valves from fully deflating the target area, thus limiting their effectiveness. Small studies have suggested that CT imaging may be sensitive, albeit not necessarily specific, for the detection of the interlobular fissures, and new automated techniques may improve its performance in this area, making it an important tool for the preprocedure planning of patients undergoing endobronchial lung volume reduction (68,69,78).…”