Application of half-dose spectral CT based on the automatic spectral imaging mode selection and adaptive statistical iterative reconstruction in the CT examination of upper abdomen in obese patients.

To investigate the value of combined use of half-dose spectral CT based on the automatic spectral imaging mode selection (GSI Assist) and adaptive statistical iterative reconstruction (ASIR) in the CT examination of upper abdomen in obese patients as compared with conventional CT. Eight-two obese patients (body mass index≥29 kg/m(2)) were prospectively selected from October to December 2016, and contrast-enhanced CT during arterial phase (AP) and portal venous phase (PVP) were carried out in those patients.The patients were randomly assigned to the study group and control group with random number table (41 cases in each group). In the study group, half-dose spectral CT based on GSI Assist was applied and monochromatic images (40 to 70 keV, 10 keV as increment) were reconstructed using 50% ASIR (group A). In the control group, the fixed tube potential of 120 kVp was done with images reconstruction using 30% ASIR (group B). Quantitative parameters of radiation dose, CT value, contrast to noise ratio (CNR) and i