Comparison to other imaging modalities
A chest computed tomography (CT) scan is considered as the gold standard for the diagnosis of COVID-19 pneumonia, having a sensitivity greater than RT-PCR [89]. Zieleskiewicz L et al demonstrated a significant association between LUS score and chest CT severity. A LUS score > 23 predicted severe SARS-CoV-2 pneumonia (specificity > 90% and a PPV of 70%) and a score < 13 excluded severe SARS-CoV-2 pneumonia (sensitivity> 90% and an NPV of 92%) diagnosed by chest CT scan[90]. Similarly, Ottaviani et al observed 21 non-ICU patients, noting the extent of affected lung using LUS score for B lines ,(wherein each lung is divided into 6 segments delineated by anterior, posterior axillary lines, parasternal and paravertebral lines), as well as the presence of ultrasound consolidations had an excellent correlation with the percentage of lung involvement on chest high resolution (HR)CT (r=0.935, p<0.001 and r=0.452, p=0.04, respectively) [91]. A significant positive correlation of LUS score with CT visual score (r = 0.65, p < 0.001) was also described in a study by Nouvenne A et al[75]. These data suggest a promising role for LUS as an alternative to CT scan for screening patients with suspicion of COVID-19, as well as assessing the severity of the disease. Shumilov et al compared LUS findings to chest X ray (CXR) in 18 symptomatic COVID-19 patients and found LUS was useful in detecting interstitial syndrome compared with CXR (94% “B-lines” vs. 61% “hazy increased opacity”; p<0.02) as well as detecting lung consolidations effectively (77% for LUS vs. 38.8% for CXR; p<0.02)[77]. Similar findings were described by Pare JR et al, wherein LUS was more sensitive than CXR (88.9% vs 51.9%, respectively) for the association of pulmonary findings of COVID-19 (p = 0.013).