Evaluation on impact of iDose~4 on dose reduction and image quality of low dose contrast-enhance chest CT

Objective To evaluate the feasibility of using iterative reconstruction(IR) algorithm(iDose4) in low dose contrast-enhanced chest CT.Methods Seventy-one patients with normal body mass index(BMI,18.5—25.0 kg/m2) underwent contrast-enhanced chest CT.The patients were randomly assigned into 3 groups: group A,120 kVp/100 mAs;group B,80 kVp/100 mAs;group C,120 kVp/50 mAs.All images were reconstructed using conventional filtered back projection(FBP) and IR.The mean image noise,SNR,CNR and effective dose(ED) with each protocol were assessed.Image quality were graded(scale: 1—3) and compared among 3 groups.Results For the same patient,IR significantly decreased the mean image noise,improved SNR and CNR compared with FBP.The mean image noise,SNR and CNR using IR in group B and C were improved or comparable to those in group A using FBP(all P0.05).No significant difference was found in subjective image quality between groups B and C using IR,nor with group A using FBP(P0.05).Conclusion It is feasible to obtain images qualified for diagnosis using IR in low dose contrast-enhanced chest CT examination.