Comparing CNR, SNR, and Image Quality of CT Images Reconstructed with Soft Kernel, Standard Kernel, and Standard Kernel plus ASIR 30% Techniques

Abstract

AIM:

Compare effect of soft kernel (SK) and 30% adaptive statistical iterative reconstruction (ASIR) and standard kernel (StK) techniques on image quality.

Materials and Methods:

Three radiologists blinded to the type of reconstruction kernel used, independently reviewed 2.5mm-thick- axial abdominal CT-scans performed for 66-randomly selected patients, optimized for oncologic imaging. The filtered-back-projection images were reconstructed using: SK, ASIR 30% and StK. The Contrast to noise ratio (CNRs) and Signal to noise ration (SNRs) were calculated. The visibility and sharpness of abdominal structures were rated (qualitatively). Summary of pair-wise comparisons among series for CNRs and SNRs were performed. Estimates and standard-error were based on a linear mixed model. P values were adjusted using the Tukey-Kramer method to control overall type I error rate.

Results:

Image series reconstructed with SK or ASIR had higher CNRs than those with StK alone (P < .009 and .002, respectively). Qualitatively images reconstructed with ASIR or SK were better than with the StK (P < .05). SK produced significantly fewer artifacts than ASIR 30%. There was no difference in the SNR among series.

Conclusion:

Images reconstructed with SK or ASIR had better image quality than StK. Scanners that cannot use ASIR may benefit from using the SK technique to improve image quality.