Feasibility study of low concentration iso_-osmolar contrast agent and low tube voltage for rabbit hepatic computed tomography perfusion scanning

Objective: To investigate the feasibility of low-concentration iso_-osmolar contrast agent together with low tube voltage and iterative reconstruction algorithm in rabbit liver computed tomography (CT) perfusion imaging. Methods: A total of 15 healthy New Zealand rabbits were scanned twice of liver CT perfusion scans each with 24 hours interval. The first scan (routine group) was acquired at 100 kV and 100 mAs with ultravist (370 mg/ml), while the second ('double low' group) was acquired at 80 kV and 100 mAs with iodixanol (270 mg/ml) at 24 hours after the first scan. The obtained images were reconstructed with filtered back projection (FBP) and adaptive iterative dose reduction(AIDR-3D) algorithms in the controlled and experimental groups, respectively. The perfusion parameters including hepatic artery perfusion(HAP), portal vein perfusion(PVP), hepatic perfusion index(HPI), and total liver perfusion(TLP) and image quality as image quality score, average CT value of abdomen aorta, signal-to-noise ratio(SNR), carrier-to-noise ratio(CNR), and figure of merit(FOM) were compared used pair t-test or Mann-Whitney U-test between the two groups wherever appropriate. The effective radiation dose and iodine intake were also recorded and compared. Results: The image quality and perfusion parameters had no significantly different between the two groups except for FOM. The effective radiation dose and iodine intake were 38.79% and 27.03% lower in the 'double low' group. Conclusions: Low concentration iso_-osmolar contrast agent (iodixanol, 270 mg/ml) together with low tube voltage (80 kV) helps to reduce radiation dose and iodine intake without compromising perfusion parameters and image quality in liver CT perfusion imaging. (authors)