Use of Iterative Reconstruction and a Small Contrast Volume in Rabbit Kidney CT: Comparison with Conventional Protocol

Abstract

Purpose: This study aimed to investigate the image quality of rabbit kidney computed tomography (CT) obtained by using a small volume of contrast material and iterative reconstruction. Materials and Methods: Twenty sedated rabbits were used in this study. In the study group, 4 mL of contrast material and iterative reconstruction were used. In the control group, 6 mL of contrast material and filtered back projection were used. First, 350 mgI/mL contrast material was administered. After 1 week, the procedure was repeated with 240 mgI/mL contrast material. Two radiologists evaluated image quality in consensus. For qualitative image assessment, sharpness, noise, texture, streak artifacts, and overall quality were rated and compared. For quantitative analysis, the CT attenuation values, image noise, signal-to-noise ratios (SNR), contrast-to-noise ratios (CNR), and figures of merit (FOM) were calculated and compared. Results: The study group images were sharper and had less noise, fewer streak artifacts, and better overall quality (all, p<0.05). However, the image texture was worse (p<0.05). Although the CT attenuation values were lower or comparable in the study group, the image noise was 42% lower with 350 mgI/mL contrast material and 36% lower with 240 mgI/mL contrast material (both, p<0.05). The SNR, CNR and FOM were higher in the study group at each dynamic phase, regardless of contrast material concentration (all, p<0.05). Conclusion: Iterative reconstruction and a small volume of contrast material can yield kidney CT images with quality comparable to those obtained with filtered back projection and a conventional volume of contrast material.