Effect of varying slice thickness on coronary calcium scoring with multislice computed tomography in vitro and in vivo.
OBJECTIVE
To compare coronary calcium scoring results (calcium volume, calcium mass, Agatston score, and number of lesions) of different slice thicknesses using a 16-slice CT (MSCT) scanner.


METHODS
A nonmoving anthropomorphic thorax phantom with calcium cylinders of different sizes and densities was scanned 30 times with repositioning applying a standardized retrospectively ECG-gated MSCT (SOMATOM Sensation 16; Siemens, Forchheim, Germany) scan protocol: collimation 12 x 0.75 mm, tube voltage 120 kV, effective tube current time-product 133 mAs(eff). Fifty patients (29 male; age 57.2 +/- 8.4 years) underwent a nonenhanced scan applying the same scan protocol. Two image sets (effective slice thicknesses 3 mm and 1 mm) were reconstructed at 60% of the RR interval. Image noise was measured in both studies. Calcium volume, calcium mass and Agatston score were calculated using a commercially available software tool.


RESULTS
Due to increased image noise in thinner slices, calcium scoring in all scans was performed applying a scoring threshold of 350 HU. In the phantom study, 1-mm slices showed significantly higher scoring results in respect to calcium volume (+8.2%), calcium mass (+12.5%), and Agatston score (+5.3%) (all P < 0.0001). In the patient study, 27 patients had coronary calcifications in 3-mm slices, and 31 patients had coronary calcifications in 1-mm slices. Thinner slices showed significantly higher scoring results in respect to volume (+47.1%), mass (+47.2%), and Agatston score (+29.7%) (all P < 0.0001).


CONCLUSIONS
When comparing 3-mm and 1-mm slices in coronary calcium scoring in MSCT, thinner slices lead to significantly increased scoring results.
Mühlenbruch
Georg
G
Department of Diagnostic Radiology, University Hospital (RWTH), Aachen, Aachen, Germany. gmuhlen@rad.rwth-aachen.de
Thomas
Christoph
C
Wildberger
Joachim E
JE
Koos
Ralf
R
Das
Marco
M
Hohl
Christian
C
Katoh
Marcus
M
Günther
Rolf W
RW
Mahnken
Andreas H
AH
D000368:Aged; D016477:Artifacts; D002114:Calcinosis / Q000000981:diagnostic imaging*; D002118:Calcium / Q000378:metabolism; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed / Q000379:methods*
D002118:Calcium