Fig E2.

SPECT image analysis of the lung ROIs. Examples of SPECT images corresponding to lower, middle, and upper lung sections 6 hours after reinjection of technetium-99m–labeled eosinophils in a healthy volunteer (left panel) and a patient with asthma (right panel). White lines represent lung ROI. At each time point, ROIs were drawn from sections of lung images. Each lung section was 4.42 mm thick and, depending on the size of the lung, the total number of sections drawn ranged from 10 to 15 at the early time points (45 min after reinjection) to 15 to 30 at time points 6 hours and later. The first lung ROI was drawn from the base of the lung, which was always at least 4 sections above the liver/spleen to avoid any scatter from these organs. Sequential ROIs were then drawn up to the top of the lung. When drawing the ROI, care was taken to avoid the signal from the mediastinum and bone marrow (vertebra, sternum, and ribs). For consistency, the saturation of the scan was adjusted at each time point and for each volunteer such that the vertebral body color had changed from blue to yellow, and then to the first hint of white. This saturation was chosen because it gave the optimal contrast between the lung and thoracic bony skeleton. The counts from each lung section were summed and expressed as counts/voxel before Patlak-Rutland analysis.