Scintigraphic Findings in Pulmonary Microembolism

A two fold scintigraphic pattern consisting of (1) decreased radioactivity along the interlobar fissure and (2) apparent diminution in the size of involved lobes is presented. The findings appear to result from multiple pulmonary microembolism—a disease entity which occurs commonly and which can produce a circumferential zone of pulmonary hypoperfusion. Reflex peripheral vasoconstriction and development of bronchopulmonary collaterals may augment this effect. "Fissural visualization" is seen more often than the "shrunken lobe," but both are fairly frequent findings. To the authors' knowledge, neither has been previously reported. It is hoped that recognition of these patterns will aid in the detection of multiple pulmonary microembolisms in the future.