Abnormal pulmonary thoracic imaging finding Pulmonary oligemia 2021-02-28T15:00:40Z See Figure 44 of Hansell DM, et al., Fleischner Society: glossary of terms for thoracic imaging. Radiology. 2008;246:697-722. Oligemia is a reduction in pulmonary blood volume. Most frequently, this reduction is regional, but occasionally it is generalized. Regional oligemia is usually associated with reduced blood flow in the oligemic area. Oligemia appears as a regional or widespread decrease in the size and number of identifiable pulmonary vessels, which is indicative of less than normal blood flow.