Assessing Lung Parenchymal Enhancement on Dual-Energy CT Pulmonary Angiograms: Potential utility of dual-energy technique as an angiographic and parenchymal 'one-stop shop' in the initial workup of patients with pulmonary symptoms.

OBJECTIVE: The aim of this study was to assess the enhancement of lung parenchyma on dual-energy (DE) computed tomogram (CT) by comparing attenuation between routine post-contrast and dual-energy generated virtual unenhanced (VU) images. METHODS: Patients presenting to the Emergency Department who subsequently underwent DE-CT pulmonary angiogram from the 1st to the 30th of November were enrolled. The DE data set obtained was used to generate VU images. Attenuation in Hounsfield units (HU) was measured at two sites for each patient and compared between VU and routine post-contrast (PC) reconstructions. Statistical analysis was performed using paired-samples t-test. RESULTS: There is a statistical difference between lung parenchymal attenuation value between the CV and PC images, denser in the PC dataset and also towards the bases, with a mean HU of -841 and -817 (difference of 24) respectively. CONCLUSIONS: This study confirms increased lung parenchymal density when comparing PC and VU reconstructions. Based on results, the paper recommends utilising dual-energy capabilities for VU reconstructions in CTPAs to optimise assessment of lung parenchyma.