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Dual-source computed tomography (DSCT) is less susceptible to cardiac motion than 64-slice multi-detector computed tomography (MDCT), says a team of researchers from the University Hospital Groningen, Netherlands. The results of a study that compared 64-slice MDCT, dual source CT and electron beam tomography (EBT) were presented on 9 March at ECR.

The group made an assessment of calcium scoring (Ca-scoring) by the three different techniques using a cardiac phantom. Three artificial arteries with calcifications of different densities were scanned at rest and at 50-110 beats per minute (bpm) with 10 bpm intervals using the three modalities. Image reconstruction was performed with slice thicknesses of 0.6 and 3.0 mm.

Agatston, volume and equivalent mass score were calculated. A Cardiac Motion Susceptibility (CMS) index was introduced to investigate the susceptibility of Ca-scoring to heart rate. A difference index was introduced to investigate the absolute Ca-scores of MDCT and DSCT versus EBT.

The study demonstrated that Ca-scores are relatively constant up to 60 bpm and start to decrease or increase above 70 bpm, depending on scoring method and density. EBT shows the lowest CMS-index. The CMS-index of DSCT is approximately half of the CMS-index of 64-slice MDCT.

Smaller slice width decreases the CMS-index for both CT-modalities. The best difference-index was found for DSCT at 0.6 mm, followed by 64-slice MDCT at 0.6 mm; the worst, for the two CT-scanners at 3.0 mm.

The researches concluded that DSCT shows less difference to absolute Ca-score on EBT than 64-slice MDCT. "A smaller slice width is beneficial to the susceptibility to cardiac motion and reduces the difference between CT-derived Ca-scores and EBT-data. The best approximation to EBT-derived Ca-scores is found for DSCT with a slice thickness of 0.6 mm.