Figure 8a. Perfusion of the lung parenchyma assessed with subtraction color-coded CT after experimental clot embolization in the PAs of a pig. Axial (a), coronal (b), and sagittal (c) CT images show multiple subsegmental perfusion defects, which are displayed in blue (arrow). The triangular perfusion defects are suggestive of emboli in small peripheral PAs. On the coronal and sagittal images, note the additional occluding subsegmental emboli (arrowhead in b and c) with resulting small peripheral perfusion defects (arrow). (Courtesy of Joachim Wildberger, MD, University Hospital of Aachen, Germany.)