Pulmonary embolism
PE obstruction index
Quantifies the clot burden of acute PE. Qanadli index on CT pulmonary angiography: 20 segmental arteries scored 0 clear, 1 partial, 2 total occlusion (a proximal clot counts every segment beyond it), index = score ÷ 40; ≥ 40% marks a high risk of RV dilatation and death. Miller index on catheter pulmonary angiography: filling defects in 16 major branches plus reduced perfusion in 6 zones, maximum 34; ≥ 17 is angiographically massive PE, and repeat scoring documents the response to thrombolysis or catheter-directed therapy.
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Imaging
Score each segmental artery: partial occlusion 1, total occlusion 2.
Right lung
Clot in a main or lobar artery: set that level, every branch beyond it fills in.
Upper lobe (3)
Apical
Posterior
Anterior
Middle lobe (2)
Lateral
Medial
Lower lobe (5)
Superior
Medial basal
Anterior basal
Lateral basal
Posterior basal
Left lung
Clot in a main or lobar artery: set that level, every branch beyond it fills in.
Upper lobe (3)
Apical
Posterior
Anterior
Lingula (2)
Superior
Inferior
Lower lobe (5)
Superior
Anterior basal
Medial basal
Lateral basal
Posterior basal
Qanadli obstruction index
0%
No obstruction scored
Score 0 / 40 · index = score ÷ 40 × 100
Decision guide
- How the index is usedClot burden is not part of the ESC 2019 risk classification, and the CT RV/LV ratio predicts death better than the obstruction index (van der Meer). Use the index to describe extent and to compare follow-up scans.
References
- Qanadli SD, et al. New CT index to quantify arterial obstruction in pulmonary embolism: comparison with angiographic index and echocardiography. AJR Am J Roentgenol 2001;176:1415-1420.
- Wu AS, et al. CT pulmonary angiography: quantification of pulmonary embolus as a predictor of patient outcome — initial experience. Radiology 2004;230:831-835.
- van der Meer RW, et al. Right ventricular dysfunction and pulmonary obstruction index at helical CT: prediction of clinical outcome during 3-month follow-up in patients with acute pulmonary embolism. Radiology 2005;235:798-803.
- Miller GA, Sutton GC, Kerr IH, Gibson RV, Honey M. Comparison of streptokinase and heparin in treatment of isolated acute massive pulmonary embolism. Br Med J 1971;2:681-684.
- Konstantinides SV, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism. Eur Heart J 2020;41:543-603.
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