Mickael Ohana MD, MSc, Presenter: Nothing to Disclose

Aissam Labani MD, Abstract Co-Author: Nothing to Disclose

Aina Venkatasamy, Abstract Co-Author: Nothing to Disclose

Mi-Young Jeung MD, Abstract Co-Author: Nothing to Disclose

Catherine Roy MD, Abstract Co-Author: Nothing to Disclose

To determine the optimal energy level for lung parenchyma analysis in spectral CT imaging.

50 dual energy CT pulmonary angiography (DE-CTPA) from a previously published prospective study were used after Institutional Review Board approvement. All patients (58% men, 64.8yo ±16) underwent a single source DE-CTPA with the following acquisition parameters: 80/140 kV, 0.6s rotation time, 275mA fixed tube current, 50% ASIR, automatic injection of 50mL of Iohexol 350mgI/mL. Monochromatic images in lung window reconstructed every 5keV from 40 to 140keV were independently assessed by two chest radiologists, based on overall image quality and the depiction of potential parenchymal lesions. Each reader had to eventually designate for every patient which keV provided the best diagnostic and image quality. A correlation between the preferred keV and the body mass index (BMI) of the patients was searched using a Pearson’s product-moment correlation.  

Mean radiation dose was 243mGy.cm ±33 and mean BMI of the participants was 25.6 ±4.5. Regarding the lung parenchyma, 28% of the examinations were normal, while the remaining 72% showed various lesions: nodule greater than 5mm (n=6), mass (n=3), alveolar consolidation (n=10), ground glass opacities (n=6), diffuse septal thickening (n=4), fibrosis (n=7), bronchiectasis (n=3) and emphysema (n=15). Reader 1 picked the 55keV monochromatic reconstruction in 52% of cases, the 50keV in 30% and the 60keV in the remaining 18%. For reader 2, the 50keV monochromatic reconstruction was preferred in 52% cases, the 55keV in 40%, the 60keV in 6% and the 40keV in 2%. The 55keV monochromatic reconstruction was chosen by at least one reader in 76% of patients, and the 50keV was preferred by at least one reader in 64% of all cases. There wasn’t any correlation between the preferred keV and the BMI for both readers (ρ<0.05 with p>0.05).

The best image quality for lung parenchyma in spectral CT is obtained with 50-55keV monochromatic reconstructions.

In dual energy chest CT, lung parenchyma is better analyzed using a 50-55keV monochromatic reconstruction.

Ohana, M, Labani, A, Venkatasamy, A, Jeung, M, Roy, C, Dual Energy CT: What Is the Optimal Energy Level for Monochromatic Imaging of Lung Parenchyma? A Qualitative Study on 50 Patients.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14015157.html