Qanadi et al reported a scoring system for the extent of pulmonary embolism as seen on CT imaging. This is related to the Miller Index. The authors are from University Rene Descartes in Paris and Centre Hospitalier de l'Universite de Montreal.
Patient selection: pulmonary embolism
Each lung is divided into 10 segments.
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Right Lung
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Left Lung
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3 segments to the upper lobe
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3 segments to the upper lobe
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2 segments to the middle lobe
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2 segments to the lingula
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5 segments to the lower lobe
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5 segments to the lower lobe
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The vascular supply to each segment is graded.
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Vascular Obstruction
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Points per Segment
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none
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0
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partial
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1
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complete
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2
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Rules:
(1) if a major artery is occluded, then all derivative segments are scored the same.
(2) if an isolated embolus is in a subsegment then 1 point is assigned for the segment.
total score for all 20 segments =
= SUM(points for vascular obstruction)
CT obstruction index =
= (total score) / 40 * 100
Interpretation:
• minimum total score and CT obstruction index: 0
• maximum total score: 40
• maximum CT obstruction index: 100%
• A CT obstruction index > 40% identifies > 90% of patients with right ventricular dilatation.
