Regional airway obstruction in cystic fibrosis determined by electrical impedance tomography in comparison with high resolution CT

Electrical impedance tomography (EIT) is able to deliver regional information to assess the airway obstruction in patients with cystic fibrosis (CF). In the present study, regional obstruction in CF patients measured by EIT was compared with high resolution computed tomography (HRCT). Five CF patients were routinely scheduled for HRCT examination. EIT measurements were performed on these patients +/- 2 months during a standard pulmonary function test. The weighted Brody score derived from HRCT, which considers bronchiectasis, mucus plugging, peribronchial thickening, parenchymal opacity and hyperinflation, was calculated from the CT scans acquired at the location of EIT electrodes +/- 5 cm. Ratios of maximum expiratory flows at 25% and 75% of vital capacity (MEF25/MEF75) with respect to relative impedance change were calculated for regional areas in EIT images. Regional airway obstruction identified in the MEF25/MEF75 maps was similar to that found in CT. Median values of MEF25/MEF75 and weighted Brody score were highly correlated (r(2) = 0.83, P < 0.05). We found that regional obstruction measured by EIT is reliable and may be used as an additional clinical examination tool for CF patients.