“…Using chest CT as the reference test, a cut-off value of 26 % or higher, representing severe bronchiectasis, was defined as a true-positive finding for the MRI-bronchiectasis subscore; 26 % represents the percentage of the maximum possible score for bronchiectasis, which is 12 per each lobe and 72 in total according to CF-CT. This cut-off of 26 % was based on the median value of bronchiectasis severity observed in two cohort studies, with either mild or severe CF lung disease [3,22], using receiveroperating characteristic analysis to determine different cut-off values. Sensitivity, specificity, PPV and NPV were calculated for each observer (obs 1 and obs 2 ), in addition to the mean of the bronchiectasis scores of both observers (mean obs 1+2 ).…”