Low-concentration contrast medium for 128-slice dual-source CT coronary angiography at a very low radiation dose using prospectively ECG-triggered high-pitch spiral acquisition.

RATIONALE AND OBJECTIVES

To assess the impact of low-concentration contrast medium on vascular enhancement, image quality, and radiation dose of coronary computed tomography (CT) angiography (CCTA) by using prospectively electrocardiography (ECG)-triggered high-pitch spiral acquisition with low tube voltage in combination with iterative reconstruction.

MATERIALS AND METHODS

One hundred patients (body mass index ≤ 25 kg/m(2), heart rate ≤ 65 beats per minute) were prospectively randomized to two groups, with 50 patients each, which were differed by contrast medium. All patients underwent prospectively ECG-triggered high-pitch spiral acquisition CCTA (2 × 128 × 0.6 mm, 300 mAs). Group A patients received iopromide 370 (370 mg I/mL), were scanned using 100 kVp, and reconstructed with filtered back projection. Group B patients received Iodixanol 270 (270 mg I/mL), were scanned using low tube voltage of 80 kVp, and reconstructed with iterative reconstruction techniques (IRT). CT attenuation was measured in coronary artery and other anatomic regions. Image quality score, noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and radiation dose were calculated and compared.

RESULTS

The iodixanol 270 group showed no significant difference in image quality score (1.61 ± 0.69 vs 1.57 ± 0.66; P > .05), CT attenuation (P > .05), noise (P > .05), SNR (47.89 ± 14.03 vs 44.37 ± 12.79; P > .05), and CNR (42.38 ± 12.67 vs 38.13 ± 11.38; P > .05) in comparison to the iopromide 370 group but at a significantly lower radiation dose (0.26 ± 0.05 vs 0.57 ± 0.10; P < .001), which reflects dose saving of 54.4%.

CONCLUSIONS

Combining IRT with high-pitch spiral acquisition mode and low-tube-voltage technique, a low-concentration contrast medium of 270 mg I/mL can still maintain the contrast enhancement in coronary arteries without impairing image quality and significantly lower the radiation dose.