Objective To investigate the in vitro CT imaging parameters of gold nanorods as novel CT contrast agents.

Methods Gold nanorods were prepared with a gold seed and a growth solution. PEG-modified gold nanorods and non-ionic iodine contrast agent were configured into eight concentrations (0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 2.0 mg/mL). The different concentrations of the gold nanorod solutions in air and water bath were subjected to in vitro CT scanning imaging at different tube voltages (80-140 kV) and milliamp seconds (50-400 mAs). The development effect was observed, and the CT value was measured.

Results (1) At different concentrations of the gold nanorod solutions, the CT value scanned in water is the closest to the true value, whereas the CT value in air is low. (2) The lower the tube voltage is, the higher the CT value of the gold nanorod solution is. At a solution concentration of 2.0 mg/mL, the difference in the signal-to-noise ratio at different tube voltages is evident. (3) The image quality is positively correlated with mAs, but the image quality is not significantly changed at ≥ 300 mAs. (3) At 80 kV and 300 mAs, the CT values of the gold nanorods and the iodine contrast agent increase as the concentration increases and show a highly positive correlation (r=0.990, 0.994, both P < 0.05). The difference in CT values between the two agents increases, and the contrast of the gold nanorods is higher than that of the iodine contrast agents.

Conclusion Gold nanorods exhibit superior imaging characteristics to those of existing CT contrast agents. When gold nanorods are scanned with iCT at 80 kV and 300 mAs and under water bath conditions, an excellent image quality can be achieved.