Variability of computed tomography angiography coverage of lung parenchyma in acute stroke

Abstract

Background: Computed tomography angiography (CTA) of the head and neck during acute ischemic stroke (AIS) usually includes visualization of lung apices. The possibility to evaluate for pulmonary changes, e.g. peripheral ground-glass and consolidative opacities suggestive of coronavirus disease 2019 (COVID-19)-related pneumonia, depends on the area of the lung covered by CTA.

Methods: We performed an analysis of a real-world scenario assessing the variability of lung coverage on CTA in patients presenting with AIS to a comprehensive stroke center (CSC) or to one of eight primary stroke centers (PSC) within a teleradiological network covered by the comprehensive stroke center in 2019.

Results: Our final analysis included n = 940 CTA, and in n = 573 (61%) merely lung apices were covered. In 19/940 (2%) of patients no lung tissue was covered by CTA. CTA scanning protocols in the CSC began significantly more frequently at the level of the ascending aorta (CSC: n = 180 (38.2%), PSC: n = 127 (27.1%), p-value < 0.001) and the aortic arch (CSC: n = 140 (29.7%), PSC: n = 83 (17.7%), p-value < 0.001), and by this covered less frequently the lower lobes compared to CTA acquired in one of the PSC.

Conclusions: In our pre-COVID-19 pandemic representative stroke patient cohort, CTA for AIS covered most often only lung apices. In 37% of the patients CTA visualized at least parts of the lower lobes, the lingula or the middle lobe allowing for a more extensive assessment of the lungs.

Keywords: COVID-19; Computed tomography angiography; Lung; Stroke; Thrombectomy.

Fig. 1

Examples of anatomical landmarks on axial CT angiography source images. a Shows a topogram of a CT angiography with reference lines corresponding to anatomical landmarks depicted in (b-j). Axial CT angiography images at the level of the aortic arch (b), supra-aortic vessels (c), cervical arteries (d), main pulmonary artery (e), carina (f) and ascending aorta (above the carina (g). The diaphragm and abdominal organs are shown in (h), the ventricles and left atrium in (i) and (j). Note: Depending on the level of the most caudal axial image the following lung segments are usually, at least partially, covered by CT angiography: B = right: 1–3, left: 1 + 2 and 3; C = right: 1 and 2, left: 1 + 2; D = no lung tissue; E = right: 1–3 and 6, left: 1 + 2, 3, 4 and 6; F = right: 1–3 and 6, left: 1 + 2, 3 and 6; G = right: 1–3, left: 1 + 2, and 3; H = right: 1–10, left: 1–10; I = right: 1–10, left: 1–10; J = right: 1–6, left: 1–6, and 8