Marie-Aurelie Delesalle, Abstract Co-Author: Nothing to Disclose

Jean-Baptiste Faivre MD, Abstract Co-Author: Nothing to Disclose

Nunzia Tacelli MD, Abstract Co-Author: Nothing to Disclose

Valérie Delannoy-Deken MS, Abstract Co-Author: Nothing to Disclose

Martine J. Remy-Jardin MD, PhD, Abstract Co-Author: Research grant, Siemens AG

Jacques Remy MD, Presenter: Research Consultant, Siemens AG

To determine the energy levels providing adequate contrast-enhancement and artifact-free depiction of systemic veins, pulmonary vessels and aorta.

80 consecutive patients underwent a dual-source, dual-energy CT angiographic examination of the chest after administration of 120 mL of iodinated contrast medium (170 mg iodine /mL). From each data set, 8 series of images were systematically reconstructed: (a) 6 monochromatic series, from 50 to 100 keV; and (b) 2 polychromatic series acquired at 80 and 140 kV. On each series of images, a quantitative and qualitative analysis of 5 anatomical compartments was obtained, including (a) the systemic veins (i.e., the brachiocephalic veins; the superior vena cava); (b) the pulmonary arteries; (c) the pulmonary veins; and (d) the aorta. The qualitative analysis included the analysis of: (a) the vessel lumen opacification, rated as homogeneous or heterogeneous; (b) the presence and severity of streak artifacts; (c) the level of subjective image noise. In the quantitative evaluation: (a) ROIs were placed in each vessel-of-interest to measure mean ±SD attenuation; (b) the signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated. For each anatomical compartment, the monochromatic series providing the best image quality in the largest number of patients was searched for and compared with images acquired at 80 kVp and 140 kVp.

For the aorta, the pulmonary arteries and veins and the right cardiac cavities, the reconstruction at 60 keV (a) was found to provide adequate attenuation in 90% of patients, with the highest CNR and the lowest levels of subjective and objective noise; (b) without significant differences when compared with images at 80 kVp. For the superior vena cava and brachiocephalic veins (a) the reconstruction at 100 keV (a) enabled artefact-free analysis of the perivascular anatomical zone; (b) without significant differences when compared to images at 140 kVp.

An optimal analysis of systemic and pulmonary circulations on mediastinal images of chest CT angiograms can be achieved by the reading of two reconstructions at 60 keV and 100 keV.

The key anatomical structures to be considered for thoracic CT contrast enhancement can be adequately analyzed by the reading of two series of mediastinal images generated from the same acquisition.

Delesalle, M, Faivre, J, Tacelli, N, Delannoy-Deken, V, Remy-Jardin, M, Remy, J, Spectral Optimization of Chest CT Angiography: Experience in 80 Patients.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11015927.html