This aggregate measures 20-40 microns in diameter which is much larger than the diameter of a lung capillary.
Pulmonary angiography is costly and invasive.
Due to risks, not used in initial workup. Ventilation imaging helps to improve specificity. Perfusion scan, even if not diagnostic, is an important guide for directing angiography catheter placement. Additional workup not required except in cases where clinical suspicion level very different than scan results. If positive, typically anticoagulate.