Which indicates a need for pulmonary angiography?

Pulmonary angiography is a specialized imaging technique used to visualize the blood vessels in the lungs and is primarily indicated when there is a need to confirm or rule out a pulmonary embolism. The need for this procedure arises particularly when preliminary tests, such as a ventilation-perfusion (V/Q) scan or CT scan, yield inconclusive results in cases where a pulmonary embolism is suspected.

When the V/Q scan shows abnormal results but cannot definitively confirm the presence of a clot, or when the CT scan does not provide clear evidence of a pulmonary embolism, pulmonary angiography becomes a necessary next step. This is because angiography can provide a more definitive visual of the pulmonary arteries and can help identify blockages or clots that the previous tests could not clearly identify. Thus, in ambiguous cases where there is a clinical suspicion of embolism, but other imaging has not clarified the diagnosis, pulmonary angiography is warranted to establish a conclusive diagnosis and guide appropriate treatment.