Case example of positive CTPA with a dual-layer spectral CT:

• the low monoenergetic (monoE, 45 keV) recons are used to provide an iodine boost to the pulmonary arteries, good if there is suboptimal contrast opacification.
• the Z effective (Zeff) recons provides a map of perfusion which details the presence of contrast in the lung, good to identify perfusion defects that may be due to subtle PEs.