key: cord-348941-orpngirf
authors: Torkian, Pooya; Rajebi, Hamid; Ramezani, Naghi; Kiani, Pejman; Akhlaghpoor, Shahram
title: Magnetic resonance imaging features of coronavirus disease 2019 (COVID-19) pneumonia: The first preliminary case series
date: 2020-09-17
journal: Clin Imaging
DOI: 10.1016/j.clinimag.2020.09.002
sha: 
doc_id: 348941
cord_uid: orpngirf

RATIONALE AND OBJECTIVES: There is a rising onus on understanding the common features of COVID-19 pneumonia on different imaging modalities. In this study, we aimed to review and depict the common MRI features of COVID-19 pneumonia in our laboratory confirmed case series, the first comprehensive reported cohort in the literature. MATERIALS AND METHODS: Upon IRB approval, eight laboratory confirmed COVID-19 patients who presented to our outpatient imaging clinic underwent chest CT and, once various features of COVID-19 pneumonia were identified, a dedicated multisequence chest MRI was performed on the same day with an institutional protocol. Demographic data and the morphology, laterality and location of the lesions were recorded for each case. RESULTS: Five males and three females with the mean age of 40.63 ± 12.64 years old were present in this case series. Five cases had typical CT features with ground glass opacities and consolidations, readily visible on different MRI sequences. Three cases had indeterminate or atypical features which were also easily seen on MRI. The comprehensive review of MRI features for each case and representative images have been illustrated. CONCLUSION: Becoming familiar with typical findings of COVID-19 pneumonia in MRI is crucial for every radiologist. Although MRI is not the modality of choice for evaluation of pulmonary opacities, it has similar capabilities in detection of COVID-19 pneumonia when compared to chest CT.

The outbreak of highly infectious novel coronavirus, known as coronavirus disease 2019 (COVID-19), has caused an emerging global health threat with more than 2,800,000 confirmed cased worldwide based on world health organization daily report as of April Although not routinely recommended, chest computed tomography (CT) is still the cornerstone of the radiologic evaluation which aids in the detection of equivocal cases, follow-up of clinically deteriorating confirmed cases, predicting mortality and early detection of complications (2-5). Cross-sectional imaging is recommended for patients with higher risk for complication, those with comorbidities, not responding to supportive treatment and presenting with acute clinical deterioration, per WHO rapid advice guide (6). Chest CT imaging features of COVID-19 has been well described in the literature. A few recent studies have demonstrated radiologic features of COVID-19 pneumonia in other diagnostic modalities, like ultrasound and PET-CT (7, 8) but no dedicated report has described magnetic resonance imaging (MRI) features of the disease.

Assessing the presence of common features of COVID-19 pneumonia as an incidental finding in MRIs performed for other reasons such as thoracic, abdomen or cardiac MRIs is necessary for every radiologist. Despite the widespread utilization of chest CT, there is an existing debate on radiation burden for the patients who undergo multiple CTs in a short time interval for follow-up purposes, especially in pediatric age group or when they are pregnant (9). Thus, this case series may start a preliminary platform for the role of MRI in disease follow-up after resolution of the symptoms, although future more comprehensive studies are required.

In this pilot study, we aimed to review and depict the common MRI features of COVID-19 pneumonia in our laboratory confirmed case series, the first comprehensive reported cohort in the literature. high prevalence and contagiousness of the COVID-19 infection, radiologists are going to encounter the many features of the associated pneumonia in their daily practice even when the MR studies are performed for other reasons. Furthermore, the reported cardiac involvement in COVID-19 infection will occasionally necessitate acquiring cardiac MR (12) . There is also open debate over associated radiation burden with CTs performed in at-risk groups like pediatric patients and pregnant females, hence raising the potential for performing state-of-the-art chest MR as a radiation-free modality in diagnosing COVID-19 pneumonia in such groups, although the challenges related to disinfection of the equipment still exists. Finally, though not well studied yet, it appears that clinically recovered COVID-19 patients may have cardiopulmonary sequelae later which may need dedicated radiologic surveillance. In that case, chest MRI examination is a viable alternative in the aforementioned groups and those who may need frequent follow up imaging.

To our knowledge, this is the first case series evaluating COVID-19 pneumonia on chest MRI. Our preliminary data on eight COVID-19 positive patients, showed that common CT manifestation of COVID-19 pneumonia such as bilateral multifocal ground-glass, consolidative, nodular or reticular opacities can be identified and distinguished on MRI, although the imaging features are not specific.

It has been shown that lung MRI is as efficient and accurate as chest CT imaging in providing fine details of the lung parenchyma and pleural abnormalities in patients with lower respiratory tract infection (13) , but the actual practical role is limited by loss of signal due to physiologic respiratory and cardiac motion, and low amount of hydrogen protons in the lung parenchyma (14) . Advancement in applicable sequence Among various MRI sequences, the T2W TSE-TIRM sequence shows lesions more brightly compared to other sequences. The increased signal intensity of the lesion in the T2W TSE-TIRM sequence is mostly due to edema, which is expected to be more observed in the inflammatory process of COVID-19 pneumonia. Also, our limited cases suggested that lung MRI could determine the different infiltration stages of the lung parenchyma. Dedicated statistically higher-level studies should be performed to determine the importance of each sequence in evaluation of COVID-19 pneumonia.

Overall, our study drives home the fact that chest MRI can act as a potential alternative to chest CT in follow-up of COVID-19 pneumonia although further studies are warranted. This also holds true in patients who require chest MRI for other indications such as vascular emergencies, myocardial infarction, or myocarditis, or routine MR spine and MR-PET for cancer staging. It is worth mentioning that a major limitation to MRI utilization in COVID-19 era is the potential risks associated with infection control after using the imaging equipment. Another limitation to our study is that our case series 

Word Health Organization. Novel Coronavirus (COVID-19) situation

Radiological Society of North America Expert Consensus Statement on Reporting Chest CT Findings Related to COVID-19. Endorsed by the Society of Thoracic Radiology, the American College of Radiology, and RSNA. Radiology: Cardiothoracic Imaging

ACR Guidance on COVID-19 and MR Use

Cardiac Involvement in a Patient With Coronavirus Disease 2019 (COVID-19)

Chest magnetic resonance imaging for pneumonia diagnosis in outpatients with lower respiratory tract infection

MR imaging of pneumonia in immunocompromised patients: comparison with helical CT

The authors declare no conflict of interest. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Protocol of the study and data will be available upon request.