Objective: To evaluate the feasibility and image quality (IQ) of prospectively high-pitch coronary CT angiography (CCTA) with low contrast medium injection rate at 70 kVp.
Materials and methods: One hundred and four patients with suspected coronary artery disease (body mass index < 26 kg/m2, sinus rhythm and heart rate < 70 beats/min) were prospectively enrolled and randomly divided into two groups. In group A and group B, 28 mL and 40 mL of 370 mgI/mL iodinated contrast media was administrated at a flow rate of 3.5 and 5 mL/s, respectively. CT values, noise, signal-to-noise ratio, contrast-to-noise ratio (CNR) of the proximal segments of coronary arteries and subjective IQ were evaluated.
Results: The CT values and noise in group A were significantly lower than those in group B (434-485 Hounsfield units [HU] vs. 772-851 HU, all p < 0.001; 17.8-22.3 vs. 23.3-26.4, all p < 0.005). The CNRs of the right coronary artery and left main artery showed no statistical difference between the two groups (42.1 ± 13.8 vs. 36.8 ± 16.0, p = 0.074; 38.7 ± 10.6 vs. 38.1 ± 17.0, p = 0.819). No statistical difference was observed between the two groups in IQ scores (3.04 ± 0.75 vs. 3.0 ± 0.79, p = 0.526) and diagnostic ratio (96.1% [50/52] vs. 94.2% [49/52], p = 0.647).
Conclusion: Prospective high-pitch CCTA at 70 kVp with 28 mL of contrast media and injection rate of 3.5 mL/s could provide diagnostic IQ for normal-weight patients with heart rate of < 70 beats/min.
Keywords: CT attenuation enhancement; Contrast medium; Coronary CT angiography; Iodine delivery rate; Low dose contrast agent; Low tube voltage; Radiation reduction.