Purpose
Computed tomography coronary artery calcium is widely used to identify and stratify risk in coronary heart disease.(Greenland et al.,
2007) A variety of techniques have been used to calculate coronary artery calcium “score” including the Agatston,
volume and mass methods.(Rumberger & Kaufman,
2003) A multi-institutional,
multi-manufacturer international standard has been established for the recommended scanning parameters to quantification of coronary artery calcium.(Mccollough et al.,
2007)
Major advances in computed tomography technology have lead to the introduction of iterative reconstruction techniques.
These enable improved image quality...
Methods and Materials
One hundred patients underwent electrocardiogram-gated CT coronary calcium scans as part of the SCOTHEART study using a 320-multidetector scanner.
Patients with a heart rate greater than 60 beats per minute received rate limiting medication (intravenous metoprolol or verapamil).
Tube voltage was set at 120kV and tube current was selected based on body mass index.
Images were acquired at either 75% or 40% of the R-R interval depending on whether the heart rate was less than or greater than 65 beats per minute.
Images were reconstructed...
Results
Thirty-seven patients had a calcium score of zero and were excluded from further analysis.
There was a small but significant difference in the median Agatston score and calcium volume between standard and iterative reconstructions (179 vs 171,
p0.008 and 157 vs 155,
p0.044 respectively).
(See Figure 1 and 2)
Image noise was significantly reduced with iterative reconstruction (26 HU (95% CI 23 to 29) vs 21 HU (19 to 24),
p<0.001).
(See Figure 3)
There was no significant difference in the estimated percentile with iterative...
Conclusion
Iterative reconstruction reduces image noise in CT coronary calcium scans.
The application of AIDR could lead to significant reduction in radiation dose.
The absolute values of both Agatston score and calcium volume are slightly reduced using iterative reconstruction.
However,
the estimated percentile for the individual patient based on age,
sex and ethnicity is not altered.
References
Agatston,
A.
S.,
Janowithz,
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Hildner,
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Zusmer,
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Viamonte,
M.,
& Detrano,
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(1990).
Quantification of coronary artery calcium using ultrafast computed tomography.
JACC,
15(4),
827-832.
Greenland,
P.,
Bonow,
R.
O.,
Brundage,
B.
H.,
Budoff,
M.
J.,
Eisenberg,
M.
J.,
Grundy,
S.
M.,
Lauer,
M.
S.,
et al.
(2007).
ACCF/AHA 2007 Clinical Expert Consensus Document on Coronary Artery Calcium Scoring by Computed Tomography in Global Cardiovascular Risk Assessment and in Evaluation of Patients with Chest Pain.
Journal of the American College...
