Editorial for "Clinical Potential of UTE-MRI for Assessing the COVID-19: Patient- and Lesion-Based Comparative Analysis".

On June 19th, 2020, the World Health Organization (WHO) officially announced that the Coronavirus Disease 2019 (COVID‐19) pandemic is accelerating. More than 150 thousand new cases were reported to the WHO on June 18th, 2020—the most in a single day so far. In the past 2 months, 6 million cases of COVID‐19 have been reported, which is substantially higher than the 85,000 cases reported during the first 2 months. Worldwide, and as of June 17th, 2020, there have been more than 8 million cases of COVID‐19 and greater than 435,000 deaths.

With sustained community transmission now established in multiple countries on multiple continents, the WHO public health goal has changed from containment to mitigation of the pandemic's impact. Consequently, strategies are now focusing on efforts to reduce the incidence, morbidity, and mortality of COVID‐19 by breaking the chain of human transmission through social distancing and imposed quarantine.

Due to the rapid spread and increasing number of COVID‐19 cases caused by a new coronavirus—severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), the rapid and accurate detection of the virus and/or the disease is increasingly vital for controlling the sources of infection and for preventing progression of the illness in patients. Real‐time reverse transcriptase‐polymerase chain reaction (RT‐PCR) for the detection of SARS‐CoV‐2 is of particular interest due to its benefits as a specific and simple qualitative assay. However, it has been reported that with this method, many “suspected” cases with the typical clinical characteristics of COVID‐19 and identical specific computed tomography (CT) images were not diagnosed.

Imaging has an important role in the identification of patients with SARS‐CoV‐2. The accurate diagnosis of viral pneumonia based on imaging may indicate isolation and can inform the management of patients with suspected SARS‐CoV‐2 infection, especially when there are no scientifically proven therapies for the treatment of COVID‐19. Early discussions suggested that CT should be the preferred modality for the diagnosis of COVID‐19. However, the use of CT for COVID‐19 diagnosis is controversial. Accordingly, the Fleischner Society published a multinational consensus statement regarding the role of CT chest imaging for the management of patients during the COVID‐19 pandemic, in three different scenarios : 1) Imaging is not indicated in patients with suspected COVID‐19 and mild clinical features unless they are at risk for disease progression; 2) Imaging is indicated in a patient with COVID‐19 and worsening respiratory status; 3) In a resource‐constrained environment, imaging is indicated for medical triage of patients with suspected COVID‐19 who present with moderate–severe clinical features and a high pretest probability of disease.

In this issue of JMRI, Yang et al8 report the results from a prospective study that aimed to evaluate the clinical potential of ultrashort echo time magnetic resonance imaging (UTE‐MRI) for the assessment of COVID‐19 using CT as the reference method. The study incorporated both lesion‐based and patient‐based comparative analyses, in addition to assessments of image quality. The study sample comprised 23 patients with confirmed COVID‐19 according to RT‐PCR, and there was an average interval of 2.81 days between the admission of patients to hospital and image examination.

All MRI examinations were performed using a 3T scanner with a 12‐channel body array in combination with a 32‐channel spine array. The MRI protocols included a traverse T2‐weighted fast spin echo sequence (FSE), coronal T2‐weighted single‐shot fast spin echo sequence (SS‐FSE), and a respiratory‐gated 3D radial UTE pulse sequence. The acquisition time varied from 4 to 5 minutes, depending on the respiration pattern of individual patients.

The authors confirmed several similarities in image quality between UTE‐MRI and CT. First, that respiratory‐gated MRI is highly effective in reducing respiratory artifacts. Second, that given the ultrashort echo time, UTE‐MRI is capable of compromising the fast T2* signal decay, which improves the signal‐to‐noise ratio of images.

Both the lesion‐ and patient‐based comparative analyses demonstrated high concordance between UTE‐MRI and CT for detecting typical pulmonary lesions including ground glass opacities (GGO), consolidation, GGO with consolidation, axial location, anteroposterior location, the number of affected lobes, the number of crazy‐paving patterns, and the number of linear opacities. However, the lesion‐based intermethod agreements for evaluating secondary signs such as air bronchogram, pseudocavity, and crazy‐paving patterns were between fair and moderate.

MRI is not considered to be a relevant tool in the routine, diagnostic work‐up for lung disorders, even during the COVID‐19 pandemic. Although MRI might be able to detect pneumonia with a high diagnostic accuracy, as shown in this article, there is no evidence of the advantages for use in this pathology, especially in an acute setting.

However, incidental findings of pneumonia might be encountered in MRI scans during the work‐up for other diseases. This is especially important given concern about the rapid and unchecked transmission of infection within communities, by individuals who have mild, or limited symptoms, or who are asymptomatic. Furthermore, the SARS‐CoV‐2 infection affects other organs, in addition to the respiratory system. Incidental lung opacities that necessitate further investigation might be assessed with UTE MRI rather than CT, especially in cases of children under general anesthesia, to avoid radiation exposure and to prevent the spread of SARS‐CoV‐2 infection.

In summary, Yang et al suggest that through assessing COVID‐19 with CT as the reference, according to lesion‐based and patient‐based comparative analysis and image quality, UTE‐MRI may act as a potential alternative to CT for the noninvasive evaluation of COVID‐19.