Tidal changes on CT and progression of ARDS

Cereda, Maurizio; Xin, Yi; Hamedani, Hooman; Bellani, Giacomo; Kadlecek, Stephen; Clapp, Justin; Guerra, Luca; Meeder, Natalie; Rajaei, Jennia; Tustison, Nicholas J; Gee, James C; Kavanagh, Brian P; Rizi, Rahim R

Beyond higher resolution, the imaging approach implemented here offers important potential advantages over previous CT approaches. In experimental injury, we used repeat CT to identify the imaging characteristics that mirror the trajectory of lung injury; this was enabled by image alignment, 9 15 which allowed tracking of individual voxels as sequential, superimposed EI-EE images over time. We thereby co-localised baseline unstable inflation with subsequent injury progression. This approach to scanning differs from a recently introduced method correlating ARDS survival with inflation heterogeneity in static CT images, but without EI-EE analysis. 7 Others have found correlations between CT imaging and ARDS outcomes, measuring the quota of tissue with recruitable atelectasis, 6 percent diseased lung 20 and evidence suggesting early fibroproliferative changes. 21 However, our methodology is unique in that it builds outcome prediction on the quantitative correlation between imaging and later injury progression, this allowed us to detect 'high-risk' tissue in areas of the lung with unstable inflation versus other states of aeration. Furthermore, this approach may unmask subtle inflation patterns that would not be noticed on conventional CT images (online supplementary figure 9 ).