In this presentation, we discuss scanning technique and present a simple, systematic, stepwise approach to the interpretation of these studies. The pulmonary arterial anatomy must first be understood, and we present a tutorial on normal pulmonary arterial anatomy down to the subsegmental level. The 3D model below represents the segmental anatomy. You can rotate this 3D model. You can access the 3D models at any time during this tutorial, using the link in the left panel labeled "3D Models".