Semiquantitative scoring of black blood slow flow score. The score is
based on how proximal signal can be seen in pulmonary arteries, where
0 = no slow flow, 1 =
signal within segmental pulmonary arteries, 2 =
signal within lobar branches, 3 = signal within
distal main pulmonary artery, 4 = signal within
proximal main pulmonary artery, and 5 = signal
within proximal main pulmonary artery. Diagram demonstrates different
parts of pulmonary artery and naming convention. Example images of each
score are provided with their mean pulmonary artery pressure
(mPAP) as a reference.