Expiratory CT: What is Good Enough?

This study obtained approval from the Institutional Review Board. The craniocaudal dimensions of inspiratory and expiratory chest CT scans of 83 patients were examined by an experienced radiologist (MS with 20 years of experience). The difference between the two measurements, called the Slice Level Difference (SLD), was calculated. Mosaic attenuation on inspiratory images and air trapping on expiratory images were quantified, as well as the change in grade between the two series. Age and gender were compared to degree of expiratory effort.