Figure 3.

Positron emission tomography images of perfusion and end-washout (End w/o) before (baseline) and after nebulized methacholine (bronchoconstriction) for Subject h021. Each row contains a selected slice of the lung from apex (top) to base (bottom) over a 10-cm span of lung. In each slice, the left lung is on the left and the right lung is on the right. Each panel of images is mean-normalized, with the color scale representing the ¹³NN activity. In the perfusion images, note the vertical gradient in perfusion from ventral to dorsal regions at baseline, but the marked heterogeneity of perfusion during bronchoconstriction. Almost all activity is washed out at baseline, but large areas of tracer retention are seen in the end w/o images during bronchoconstriction, and these areas correspond to areas of low perfusion.