Carlo Nicola de Cecco MD, Presenter: Nothing to Disclose

James Spearman, Abstract Co-Author: Nothing to Disclose

U. Joseph Schoepf MD, Abstract Co-Author: Research Grant, Bracco Group Research Grant, Bayer AG Research Grant, General Electric Company Research Grant, Siemens AG

Christian Canstein, Abstract Co-Author: Employee, Siemens AG

Felix G. Meinel MD, Abstract Co-Author: Nothing to Disclose

Andrew D. Hardie MD, Abstract Co-Author: Nothing to Disclose

Philip Costello MD, Abstract Co-Author: Nothing to Disclose

To evaluate whether a dedicated image-based algorithm for virtual monoenergetic imaging (Mono+) with a third-generation dual-energy, dual-source CT scanner can improve the contrast-to-noise ratio (CNR) of liver parenchyma in comparison with a standard virtual monoenergetic algorithm and also 100 and 120kV polyenergetic data-sets.

Eight patients underwent abdominal CT examinations including single-energy unenhanced (120kV, 147ref.mAs) and dual-energy portal phase (100/Sn150kV, 180/90ref.mAs) imaging. Dual-energy data were processed, and virtual monoenergetic images (range, 40-120/150/190keV) were generated using both standard monoenergetic and Mono+ algorithms. The new algorithm performs a regional analysis-dependent frequency-based recombination of the high signal at lower energies and the superior noise properties at medium energies to optimize CNR and avoid the noise increases at lower calculated energies which are commonly observed with standard algorithms. Liver parenchyma and intrahepatic portal vein attenuation and image noise were measured and the CNR was subsequently calculated. Differences in liver attenuation and CNR were compared between the different virtual monoenergetic datasets and the standard 100 and 120kV polyenergetic datasets.

For Mono+, the optimum CNR was obtained at the lowest energy level of 40keV (10.9±13.5HU) while the optimum CNR of the standard monoenergetic algorithm was at 70keV (5.7±28.0HU). The CNR of Mono+ reconstructions was 47% greater than with the standard monoenergetic algorithm. Compared with the corresponding standard 40 keV data-set, the incremental improvement in CNR was even higher (3.6±15.8HU, 67% increment). The optimum Mono+ CNR at 40keV was also significantly higher than the CNR in the standard 120kV polyenergetic data-set (4.0±50.3HU, 63% improvement) and in the 100kV data-set (5.7±40.9HU, 39% improvement). In fact, all Mono+ data-sets from 40 to 70keV had a CNR significantly higher than the optimum standard monoenergetic reconstructions at 70keV as well as the 100 and 120kV polyenergetic datasets.

Mono+ virtual monoenergetic images have a significantly higher CNR for liver CT imaging compared with both standard virtual monoenergetic algorithms and 100 and 120 kV polyenergetic images.

Mono+ improves the quality of virtual monoenergetic images, which may enhance diagnostic performance and reduce contrast medium volumes.

de Cecco, C, Spearman, J, Schoepf, U, Canstein, C, Meinel, F, Hardie, A, Costello, P, Value of an Advanced Image-based Technique to Calculate Virtual Monoenergetic CT Images Using Third-generation Dual-energy Dual-source CT to Improve Contrast-to-Noise Ratio in Liver Examinations.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14019076.html