Comparison of software based CT fissure analyses and endobronchialin-vivomeasurements for detection of collateral ventilation for endoscopic lung volume reduction

It has become clinical routine to assess interlobar collateral ventilation (CV) prior to endoscopic lung volume reduction (ELVR), mainly by endobronchial in-vivo measurement (Chartis, Pulmonx Inc., USA) or software based quantitative analyses of fissure integrity (FI) from CT scans (QCT). We asked the question, whether Chartis or QCT is better to exclude CV. 52 severe COPD patients received Chartis assessments in 121 lung lobes prior to ELVR. In a retrospective analysis, QCT (Thirona, Netherlands) were compared to Chartis assessments. ROC analysis was performed to determine the cut-off value for FI. 32 patients with absence of CV by Chartis were treated with endobronchial valves. A target lobe volume reduction (TLVR) over 350ml was defined as a positive response to valve insertion and used for defining the accuracy of Chartis and fissure analysis to predict the clinical outcomes. The CV negative lobes as defined by Chartis showed a mean FI of 98.9±0.7% and the CV positive lobes of 79.3±3.6% (p 350ml was 76.9% with QCT and 83.3% with Chartis. Chartis and QCT showed a similar accuracy to predict the clinical outcomes after ELVR. The right minor fissure is mainly responsible for interlobar CV, thus the left lung is a more frequent target for valve therapy.