Imaging: Contiguous 3 mm slices through the proximal coronary arteries
For each zone of calcification identified, the following were measured:
(1) area in square millimeters within the outer circumference of the calcification
(2) peak X-ray density in Hounsfield units
|
Area in square mm
|
Points
|
|
< 1 square mm
|
0
|
|
>= 1 square mm
|
(area)
|
|
Peak X-ray Density in Hounsfield (Hn) Units
|
Points
|
|
< 130
|
0
|
|
130 – 199
|
1
|
|
299 - 299
|
2
|
|
300 – 399
|
3
|
|
>= 400
|
4
|
where:
• The limit on area scoring eliminates single pixels that might be due to noise
• Some authors score 400 Hn units as 3, while others as 4.
score for each zone of calcification =
= (area in square mm) * (points for peak X-ray density)
total coronary artery calcium score =
= SUM(scores for all zones detected)
Interpretation:
• minimum score: 0
• maximum score: > 1,000
• The higher the score, the more extensive and severe the coronary artery disease.
