To compare the image quality of mono- versus bisegment reconstruction algorithms for dual-source computed tomography coronary angiography (CTCA).
Materials and Methods:
Eighty consecutive patients (27 women; average age, 60 ± 12 years) were randomly assigned to 2 different CTCA scanning protocols: 40 patients (group A) underwent dual-source CTCA with a heart rate (HR)-dependent pitch adaptation with datasets reconstructed using the monosegment algorithm; 40 patients (group B) underwent CTCA at a fixed pitch of 0.2 and datasets were reconstructed using both mono- and bisegment algorithms. The temporal resolution was 82 milliseconds for mono- and 42 to 83 milliseconds (58 ± 14 milliseconds) for bisegment reconstruction, the latter depending on the HR during CTCA. Images were reconstructed in the reconstruction phase having least motion artifacts in the individual patient, primarily during mid-diastole at 70% of the R-R interval. The HR variability was defined as the standard deviation from the average HR. Two blinded observers independently assessed the image quality of each coronary segment using a 4-point scale (1: excellent to 4: nonevaluable). Effective radiation dose estimates were calculated.
The overall image quality showed no significant differences between the 2 groups scanned with a fixed or a HR-adapted pitch (group A, score 1.21 ± 0.63; group B, score 1.19 ± 0.52). The overall image quality was superior when using monosegment (group A and B, score 1.21 ± 0.63 and 1.19 ± 0.52, respectively) when compared with the bisegment reconstruction algorithm (group B, score 1.33 ± 0.72; P < 0.01). Image quality did not significantly correlate with average HR neither for monosegment (group A: r = 0.07; P = 0.35; group B: r = 0.06; P = 0.41) nor bisegment reconstructions (r = 0.07; P = 0.32). There was no significant correlation between image quality and HR variability using monosegment reconstructions (group A: r = 0.09; P = 0.22; group B: r = 0.05; P = 0.67), whereas a significant correlation was found for bisegment reconstructions (group B: r = 0.51; P < 0.01). The estimated effective radiation dose was significantly higher in group B (10.8 ± 1.4 mSv) when compared with group A (9.0 ± 0.8 mSv; P < 0.01).
Although providing a higher temporal resolution at certain HRs, the use of bisegment reconstructions for dual-source CTCA does not result in an improved overall image quality when compared with the monosegment reconstruction algorithm.