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Figure 4a. Spiral CT scans obtained over 16 months in a 27-year-old woman with acute PE who presented with right-sided chest pain at the initial diagnosis. (a) Spiral CT scan (5-mm collimation, pitch of 1, 30% iodinated contrast agent) obtained at the level of the right bronchus intermedius at the time of initial diagnosis shows a complete obstruction of the right interlobar pulmonary artery (arrow). (b) Follow-up spiral CT scan (3-mm collimation, pitch of 1.7, 25% iodinated contrast agent) obtained at the same level as a, 16 months later, shows the dramatic reduction in diameter of the right interlobar pulmonary artery (arrow), partially recanalized.