Model-Based Iterative Reconstruction Better for Neck CT

October 15, 2014

Image quality of neck CTs is improved with the use of model-based iterative reconstruction, compared with 30% adaptive statistical iterative reconstruction.

Model-based iterative reconstruction improves image quality for contrast-enhanced CT of the neck, according to a study published in the American Journal of Neuroradiology.

For this study, researchers from the University of Washington compared image quality of 30% adaptive statistical iterative reconstruction and model-based iterative reconstruction algorithms for the assessment of image quality of contrast-enhanced CT of the neck.

They retrospectively reconstructed neck contrast-enhanced CT data from 64 consecutive patients using the two methods. “Objective image quality was assessed by comparing signal-to-noise ratio (SNR), contrast-to-noise ratio, and background noise at levels 1 (mandible) and 2 (superior mediastinum),” the authors wrote. The images were graded by two independent blinded readers, using a scale of 1 to 5, with grade 5 equal to excellent image quality without artifacts and 1 equal to nondiagnostic image quality with significant artifacts.

The results showed that the model-based iterative reconstruction significantly improved the SNR and contrast-to-noise ratio at levels 1 and 2, compared with the 30% adaptive statistical iterative reconstruction. ”Model-based iterative reconstruction also decreased background noise at level 1, though there was no difference at level 2,” they noted. “Model-based iterative reconstruction was scored higher than 30% adaptive statistical iterative reconstruction by both reviewers at the nasopharynx and oropharynx and for overall image quality and was scored lower at the vocal cords and sternoclavicular junction, due to artifacts related to thyroid shielding that were specific for model-based iterative reconstruction.”

The researchers concluded that the model-based iterative reconstruction offered both improved subjective and objective quality for contrast-enhanced neck CTs, with the additional advantage of reducing radiation dose while maintaining image quality. However, the method does have a “minor downside,” the authors wrote, of having prominent artifacts related to thyroid shield use.