Examples of study- and image-level labels. (a) Central
Pulmonary Embolism (PE): saddle embolus within the main, right, and left
pulmonary arteries (arrow). (b) Right-sided PE and
Left-sided PE: pulmonary emboli within the right interlobar, right lower
lobe (arrow), and lingular pulmonary arteries (arrowhead).
(c) Chronic PE: nonocclusive intraluminal web within
the right lower lobe pulmonary artery (arrow). (d) True
Filling Defect not PE: left lung malignancy invading the left main
pulmonary artery. (e) Flow Artifact: an apparent filling
defect within the left pulmonary artery, which is due to laminar flow of
contrast media rather than PE (arrow). (f) RV/LV Ratio:
< 1: normal RV (red line) to LV (blue line) ratio. (g)
RV/LV Ratio: ≥ 1: evidence of right heart strain characterized by
an elevated RV/LV ratio. (h) QA-motion: impaired image
quality at the lung bases due to respiratory motion (arrows).
(i) QA-contrast: insufficient opacification of the
pulmonary arterial tree (arrow) to allow for the assessment of PE. LV
= left ventricle, QA = quality assurance RV = right
ventricle.