The capabilities of MRI in the lung lesions diagnosis in patients with COVID-19

Backgrounds. The imaging diagnostic methods have become particularly important during the COVID-19 pandemic, and computed tomography of the thorax (CT) is considered to be the “gold standard” in the cases of lung lesions and in the evaluation of changes in the pulmonary parenchyma in dynamics. However, it is well known that the CT method is associated with a significant radiation dose, especially given the fact that repeated, and often reiterated control CT-tests are required for many patients who suffer COVID-19 or have recovered from the disease. In order to reduce the potential radiation exposure and receive some additional diagnostic information, we applied the magnetic resonance imaging (MRI) method for viral pneumonia at the FRCC of FMBA of Russia, which was redesigned as a center for the treatment of patients with COVID-19.

Aim. The aim is to evaluate the possibilities of the lung MRI in the diagnosis of pneumonia caused by the new coronaviral infection, to describe the specific symptoms of lung parenchyma lesions using various pulse sequences, and compare the results with the CT data.

Methods. The article is based on the practice of applying high-resolution computed tomography (HRCT) and MRI of the lungs in 15 patients with pneumonia caused by COVID-19.

Results. The comparison of the HRCT data and T2-weighted images (T2-WI) in 100% of cases revealed a complete correlation in the size, number and position of the lung tissue areas with reduced air saturation by the type of ground glass opacity and the consolidation zones. The level of linear and reticular changes detection in MRI reached 73.3%. Free fluid in the pleural cavities in a moderate and minimal volume was revealed on T2-WI in 12 patients (80% of cases), while it was not diagnosed by HRCT in all the cases. The mediastinal and intra-pulmonary lymph nodes were visualized distinctly. In T1-weighted images (T1-WI), the areas of ground glass opacity were either not visualized, or were represented by smaller areas when compared to the HRCV data and reticular changes were also displayed worse. In 73.3% cases, the consolidation zones on T1-WI fully corresponded or were almost similar in characteristics to changes visualized by HRCT. At the same time, it is worth noting that performing T1-WI out phase more clearly displayed the consolidation zones when compared to T1-WI in phase. Foci of increased signal on T1-WI with fat suppression were registered in 3 patients against the background of consolidation sites which in comparison with the data of T2-WI, would suggest the presence of parenchymal hemorrhages.

Conclusion. Lung MRI is a fairly sensitive method for identifying areas of ground glass opacity and consolidation, reticular changes and lymphadenopathy, and is superior to HRCT when displaying pleural effusion. Chest MRI may be recommended as a diagnostic method for suspected pulmonary COVID-19 lesion in children and pregnant women in order to exclude ionizing radiation exposure, as well as for monitoring the condition of lung tissue after viral pneumonia, if the patient was previously exposed to a high radiation dose.