Figure 24a. Flow-related artifact in a 73-year-old woman with chest pain. (a) CT scan shows poor enhancement of the interlobar and middle lobe pulmonary arteries due to flow-related artifact. More distally, the pulmonary arteries were well enhanced. Note also the fluid-filled, dilated esophagus. (b) Repeat CT pulmonary angiogram demonstrates segmental pulmonary emboli within the medial and lateral segmental branches of the middle lobe artery (arrows).