A standardised and evidenced-based lung ultrasound acquisition protocol and scoring system for the monitoring and stratification of COVID-19 and post-COVID-19 patients

Lung ultrasound (LUS) is currently utilized worldwide to assess COVID-19 patients. However, imaging protocols are often defined arbitrarily, and studies on post-COVID-19 are lacking. In this work, we report on the capabilities of standardized LUS to monitor and stratify COVID-19 and post-COVID-19 patients. A validated and standardized imaging protocol based on 14 scanning-areas and a 4-level scoring system were utilized to collect and analyze data from 220 patients, 100 COVID-19 positive, and 120 post-COVID-19. Next, the capability of five imaging protocols (based on 4, 8, 10, 12, and 14 scanning-areas) to intercept the most significant LUS findings was compared. Moreover, a longitudinal-study was conducted aiming at investigating the possibility to simplify the protocol during follow-up. Results on the agreement between AI-models and LUS experts with respect to LUS data evaluation are also reported. In conclusion, a 12-areas protocol emerges as the optimal trade-off between a time-efficient and an accurate LUS examination. However, it appears not to be possible to reduce further the number of scanning-areas during follow-up. Finally, COVID-19 and post-COVID-19 data seem to show differences capable to confuse AI models that were not trained on post-COVID-19 data, supporting the hypothesis of the existence of LUS patterns specific to post-COVID-19.