Figure 1

Illustrative examples of a patient with lobar attenuations (top) and a patient with diffuse attenuations (bottom). Left panels: computed tomography (CT) scan of the right lung; right panels: volumic distribution of CT numbers for the upper lobe. The volumes of gas and tissue computed with Lungview are shown above the CT attenuation histogram. The excess lung tissue present in the upper lobes is similar in the two patients. In contrast, there is four times as much gas in the upper lobe of the patient with lobar attenuations as in the upper lobe of the patient with diffuse attenuations. This difference in the fraction of gas markedly affects the CT image, the upper lobe of the patient with lobar attenuations appearing grossly ‘normal’ whereas the upper lobe of the patient with diffuse attenuations appears ‘abnormal’. Reproduced from [17] with permission from Springer Science and Business Media.