Secondary outcomes
SECONDARY

The percentages of different aeration volumes were considered as secondary outcomes. Areas of different aeration were measured using a workstation software (Sinvo.gia, Siemens Healthcare GmbH) by setting the histogram parameters between − 1,000 and − 901, − 900 and − 501, and − 500 and − 101 Hounsfield Units for over-aeration, normal-aeration, and poor-aeration, respectively [