Objectives

Review the principles of DECT acquisition and post-processing.

Review artefacts encountered in DECT imaging.

Discuss potential challenges and pitfalls while interpreting DECT and how to overcome them.

Background

Dual energy computed tomography (DECT) involves acquisition with two x-ray energy spectra enabling superior tissue characterization than conventional CT and has gained increased utility in imaging. Hence it is important for Radiologists to understand the imaging principles and interpretation of DECT. We aim to discuss the unique imaging artefacts, potential challenges and pitfalls DECT image interpretation, specifically with regards to abdominal imaging.

Imaging findings OR Procedure findings

1. Beam hardening and metal artefacts on post-processed images:

Accentuated on low keV images

May result in false appearance of excessive amount or lack of iodine on colour-coded iodine images

2. Image noise on Virtual Monochromatic images:

Degradation of image quality

Tends to occur predominantly towards the end of the energy spectra.

3. Noise and “pseudoenhancement” on colour-coded iodine images:

Results in wrong interpretation of presence of iodine in lesions. Reviewing virtual monochromatic images and improving algorithms used for iodine quantification would be useful

4. Imperfect iodine subtraction:

Virtual non-contrast images may be of suboptimal quality showing iodine, especially with high concentrations of iodine (for example, contrast within renal collecting systems).

Conclusion

DECT adds value in abdominal imaging by its superior tissue characterization. However, there are unique challenges in image interpretation. It is important for radiologists to be aware of these and familiarize themselves with strategies to overcome them.