Influence of slice thickness and reconstruction kernel on the computed tomographic attenuation of coronary atherosclerotic plaque.
BACKGROUND
The computed tomographic (CT) attenuation of coronary atherosclerotic plaque has been proposed as a marker for tissue characterization and may thus potentially contribute to the assessment of plaque instability.


OBJECTIVE
We analyzed the influence of reconstruction parameters on CT attenuation measured within noncalcified coronary atherosclerotic lesions.


METHODS
Seventy-two patients were studied by contrast-enhanced dual-source CT coronary angiography (330 millisecond rotation time, 2 x 64 x 0.6 mm collimation, 120 kV, 400 mAs, 80 mL contrast agent intravenously at 6 mL/s), and a total of 100 distinct noncalcified coronary atherosclerotic plaques were identified. Image data sets were reconstructed with a soft (B20f), medium soft (B26f), and sharp (B46f) reconstruction kernel. With the medium soft kernel, image data sets were reconstructed with a slice thickness/increment of 0.6/0.3 mm, 0.75/0.4 mm, and 1.0/0.5mm. Within each plaque, CT attenuation was measured.


RESULTS
Mean CT attenuation using the medium soft kernel was 109 +/- 58 HU (range, -16 to 168 HU). Using the soft kernel, mean density was 113 +/- 57 HU (range, -13 to 169 HU), and using a sharp kernel, mean density was 97 +/- 49 HU (range, -23 to 131 HU). Similarly, reconstructed slice thickness had a significant influence on the measured CT attenuation (mean values for medium soft kernel: 102 +/- 52 HU versus 109 +/- 58 HU versus 113 +/- 57 HU for 0.6-mm, 0.75-mm, and 1.0-mm slice thickness). The differences between 0.75-mm and 0.6-mm slice thickness (P = 0.05) and between medium sharp and sharp kernels (P = 0.02) were statistically significant.


CONCLUSIONS
Image reconstruction significantly influences CT attenuation of noncalcified coronary atherosclerotic plaque. With decreasing spatial resolution (softer kernel or thicker slices), CT attenuation increases significantly. Using absolute CT attenuation values for plaque characterization may therefore be problematic.
Achenbach
Stephan
S
Department of Cardiology, University of Erlangen, 91054 Erlangen, Germany. stephan.achenbach@uk-erlangen.de
Boehmer
Kerstin
K
Pflederer
Tobias
T
Ropers
Dieter
D
Seltmann
Martin
M
Lell
Michael
M
Anders
Katharina
K
Kuettner
Axel
A
Uder
Michael
M
Daniel
Werner G
WG
Marwan
Mohamed
M
D000368:Aged; D002114:Calcinosis; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D003331:Coronary Vessels; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media