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 compare image quality, attenuation and radiation dose between virtual unenhanced (VU) and conventional unenhanced (CU) datasets of the abdomen obtained with a 3rd generation dual-source dual-energy CT system (DECT). The impact of a 3rd generation iterative reconstruction algorithm (ADMIRE) was also assessed in comparison to filtered back projection (FBP).

Eight patients underwent triphasic abdominal CT examinations including single-energy CU (120kV, 147 ref.mAs) and dual-energy arterial and portal venous phase acquisitions (100/Sn150kV, 180/90 ref.mAs). VU images were generated from arterial (AVU) and portal venous (PVU) phases. CU, AVU and PVU data-sets were reconstructed using FBP and ADMIRE (strength 3). Two abdominal radiologists analyzed the image quality using a five-point scale. Radiation dose, attenuation and noise of the abdominal organs and aortic calcifications were recorded for both FBP and ADMIRE in CU, AVU and PVU datasets. 

Mean image quality scores of DECT VU images with ADMIRE was not significantly different than the mean image quality of CU images (4.830.12) for both AVU (4.790.9) and PVU (4.750.14), (p>.05). The mean attenuation values of liver, spleen, pancreas, renal cortex, aorta, and retroperitoneal fat did not differ significantly among CU, AVU, and PVU images (p>.05). There was however a significant difference in mean attenuation for small calcified aortic plaques, with a reduction in density for VU images (37939, 21756, 33478 HU for CU, AVU and PVU, respectively, p<.01). The radiation dose of the single-energy and dual-energy acquisitions did not differ significantly (3.221.25, 3.251.26, 3.231.27 mSv for CU, AVU and PVU, respectively, p>.05). The potential dose reduction that would have been achieved by omitting the unenhanced acquisition was 33.2% (p<.01).

3rd generation DECT VU images with the ADMIRE iterative reconstruction algorithm showed comparable image quality as single energy CU images with complete iodine subtraction, albeit with a reduction in the density of calcifications on VU images. There was no significant difference in radiation dose between dual-energy and single energy acquisitions.

Despite an imperfect calcium subtraction, a  3rd generation DECT VU imaging technique using the ADMIRE algorithm has the potential to replace CU images in clinical practice.

de Cecco, C, Spearman, J, Schoepf, U, Canstein, C, Meinel, F, Hardie, A, Costello, P, Virtual Unenhanced Images of the Abdomen with Third-generation Dual-source Dual-energy CT and Third-generation Iterative Reconstruction: Image Quality, Attenuation and Radiation Dose.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14018537.html