Low-dose CT coronary angiography using iterative reconstruction with a 256-slice CT scanner

Table 1 Demographical characteristics, acquisition parameters, radiation dose and image quality

	FBP	IR	P value
Age (yr)	55.6 ± 9.1	56.0 ± 10.1	0.67
Male	85 (85)	80 (80)	0.35
Body mass index (kg/m2)	27.2 ± 2.7	26.3 ± 3.4	0.03
Body mass index ≥ 30	15 (15)	13 (13)	0.68
Heart rate (bpm)	58.3 ± 7.0	58.2 ± 6.4	0.88
Acquisition technique
Prospective (axial)	84 (84)	82 (82)	0.71
Retrospective (helical)	16 (16)	18 (18)
Tube voltage (kV)	119.0 ± 4.4	109.0 ± 10.4	< 0.0001
Percent 80-100 kV	5 (5)	54 (54)	< 0.0001
mAs in prospective	203.1 ± 15.4	195.7 ± 26.8	< 0.0001
mAs in helical	943.2 ± 119.5	870.1 ± 122.8	< 0.0001
Radiation dose (mSv)
Total	4.6 ± 3.0	2.8 ± 1.4	< 0.0001
Prospective (axial)	3.4 ± 2.4	2.4 ± 0.7	< 0.0001
Retrospective (helical)	10.3 ± 3.9	5.2 ± 1.6	< 0.0001
Image quality
Attenuation level (HU)	461.7 ± 51.9	462.2 ± 51.2	0.54
Image noise (HU)	37.8 ± 1.4	38.2 ± 2.4	0.20
Signal to noise ratio	12.2 ± 1.4	12.1 ± 1.4	0.28
Coronary assessment (%)	91.7 ± 4.0	92.5 ± 2.8	0.12

Data are expressed as absolute numbers (percentage) or mean ± SD. FBP: Filtered back projection; IR: Iterative reconstruction.