Point-of-care contrast enhanced lung ultrasound and COVID-19

Abstract

Objectives Bedside lung ultrasound has been indispensable during the coronavirus disease 2019 (COVID-19) pandemic, allowing us to rapidly assess critically unwell patients. We demonstrate the unique application of contrast-enhanced ultrasound with the aim of further understanding this disease. Methods Patient demographics were recorded alongside recent cross-sectional imaging and inflammatory markers. Ultrasound was conducted by experienced operators in a portable setting. Conventional six-point lung ultrasound method was used to evaluate B-lines, small (subpleural) consolidation and the pleura. Areas of small consolidation were targeted after intravenous administration of ultrasound contrast. Results The areas of small consolidations, a potential sign of pneumonia on B-mode lung ultrasound, usually enhance on contrast-enhanced ultrasound. Our study revealed these areas to be avascular, indicating an underlying thrombotic/infarction process. Findings were present in 100% of the patients we examined. We have also shown that the degree of infarction correlates with CT severity (r = 0.4) and inflammatory markers, and that these areas improve as patients recover. Conclusions We confirmed the theory of immune thrombus by identifying the presence of microthrombi in the lungs of 100% of our patients, despite 79% having had a recent negative CT pulmonary angiogram study. contrast-enhanced ultrasound can be utilised to add confidence to an uncertain COVID-19 diagnosis and for prognosticating and monitoring progress in confirmed COVID-19 patients. Contrast-enhanced ultrasound is clearly very different to CT, the gold standard, and while there are specific pathologies that can only be detected on CT, contrast-enhanced ultrasound has many advantages, most notability the ability to pick up microthrombi at the periphery of the lungs.

The Diagnostic Role of Lung Ultrasound and Contrast-Enhanced Ultrasound in Pulmonary Embolism

“…53 Notably, avascular areas suggestive of pulmonary infarctions were detected on LUS in 100% of patients enrolled in the study, despite 79% having a recent negative CT pulmonary angiogram. 53…”

“…The authors demonstrated that the degree of infarction correlates with the severity of COVID-19 pneumonia (r ¼ 0.4) on CT scan and with inflammatory markers, and that these areas improved as patients recovered. 53 Notably, avascular areas suggestive of pulmonary infarctions were detected on LUS in 100% of patients enrolled in the study, despite 79% having a recent negative CT pulmonary angiogram. 53 Lung Ultrasound versus Computed Tomographic Pulmonary Angiography CTPA is the gold standard for the diagnosis of PE, thanks to its high sensitivity and specificity.…”

“…Tee et al investigated small subpleural consolidations in COVID-19 patients by administrating CEUS 53 ; these areas were avascular, thus suggesting an underlying thrombotic/infarction process. The authors demonstrated that the degree of infarction correlates with the severity of COVID-19 pneumonia ( r = 0.4) on CT scan and with inflammatory markers, and that these areas improved as patients recovered.…”

Association Between Lung Ultrasound Patterns and Pneumonia

“…20 Studies that used contrast-enhanced ultrasound in patients with pneumonia found perfusion defects within consolidations, suggesting that it could be caused by ischemic or necrotic changes that differ from inflammatory causes in consolidations. 21,22 This indicates that the use of contrast-enhanced LUS could provide pathogenetic interpretations of consolidations in patients with pneumonia. Future studies aiming to quantify the types and stages of pneumonia using advanced ultrasound imaging techniques are encouraged.…”

“…The LUS features of consolidation in patients with pneumonia include a hypoechoic area with irregular and serrated margins that exhibits heterogeneous echotexture caused by focal air inclusions, and homogeneous sub-pleural section 20 . Studies that used contrast-enhanced ultrasound in patients with pneumonia found perfusion defects within consolidations, suggesting that it could be caused by ischemic or necrotic changes that differ from inflammatory causes in consolidations 21,22 . This indicates that the use of contrast-enhanced LUS could provide pathogenetic interpretations of consolidations in patients with pneumonia.…”