OBJECTIVETo investigate the feasibility of using lower iodine concentration (270 mgI/ml) contrast medium, lower X-ray tube voltage (100 kVp) and iterative reconstruction (IR) to reduce both iodine load and radiation dose but keep the image quality of coronary CT angiography (CCTA).

METHODSA total of 80 consecutive patients with suspected coronary artery disease were prospectively assigned to one of two groups via computer central system from January to May 2013. The control group (n = 40) was scanned using dual-source CCTA protocols of 120 kV, 370 mgI/ml Iopromide and filtered back projection reconstruction with a vascular algorithm (B26f). The study group (n = 40) was scanned using 100 kV, 270 mgI/ml Iodixanol and sinogram affirmed iterative reconstruction with a vascular algorithm (I26f). Other scan parameters and contrast injection protocol were similar between the two groups. Attenuation in the ascending aorta and coronary arteries along with image noise were measured. Images were reconstructed, measured and graded, and iodine load and effective radiation dose were calculated.

RESULTSThe body mass index ((25.3 ± 3.0) kg/m² vs. (25.4 ± 3.0)kg/m², P = 0.852), image quality scores (4.70 ± 0.52 vs. 4.63 ± 0.59, P = 0.545), mean signal-to-noise ratios (22.2 ± 5.5 vs. 23.6 ± 5.8, P = 0.277), and contrast-to-noise ratios (35.6 ± 17.6 vs. 41.1 ± 17.6, P = 0.163) were similar between the control group and study group. Mean iodine loads were significantly reduced in the study group ((18.49 ± 0.75)g) compared to control group ((25.27 ± 0.94)g), P< 0.001). Mean effective radiation doses were also significantly reduced in the study group ((2.31 ± 0.73) mSv) compared to that in control group ((3.52 ± 1.16) mSv), P< 0.001).

CONCLUSIONUse of low X-ray tube voltage and iterative reconstruction allows lower iodine load and effective radiation dose application at CCTA without image quality reduction.