From Radiological Manifestations to Pulmonary Pathogenesis of COVID-19: A Bench to Bedside Review

Low-dose tocilizumab is associated with improved outcome and a low risk of secondary infection in severe COVID-19 pneumonia

BACKGROUND

Respiratory failure and death are the leading causes of severe Coronavirus disease 2019 (COVID-19). Hyper-inflammation and cytokine storm cause lung damage. This study aimed to compare the low-dose and high-dose effects of tocilizumab, an IL-6 receptor antagonist.

METHOD

Patients with severe pneumonia and hyper-inflammation signs because of COVID-19 were included in this retrospective study. Patients receiving tocilizumab <200 mg intravenously were classified as the low-dose group, and receiving ≥200 mg as the high-dose group, and those not treated with tocilizumab as the control group. Demographic and clinical data of patients who died and survived in both low-high dose and control patients were compared. According to symptom day and radiological infiltration, patients with tocilizumab were also evaluated in two groups as early and late periods at tocilizumab administration time.

RESULTS

A total of 160 patients were included in the study; 70 were treated with a low dose and 50 with high-dose tocilizumab. Forty patients were in the control group. Age, comorbidity and clinical features were similar in the control, low-dose tocilizumab and high-dose tocilizumab groups. The mortality rate (12.9%, 30.0%, 37.5, P = .008) was less in the low-dose tocilizumab group. The secondary infection rate was higher in the high-dose group than in the low-dose tocilizumab and control groups (44.0%, 10.0%, 10.0%, P < .001). Distinguishing between those patients who died and survived, age (OR: 1.1589, P < .001), higher APACHE II scores (OR: 1.225, P = .001) and needs for non-invasive mechanical ventilation (OR: 14.469, P < .001) were the most critical risk factors. Low-dose tocilizumab was associated with a lower mortality rate (OR: 0.244, P = .012).

CONCLUSION

The use of tocilizumab at a low dose is associated with lower secondary infections and mortality.

“Pulmonary target sign” as a diagnostic feature in chest computed tomography of COVID-19

BACKGROUND

In chest computed tomography (CT) scan, bilateral peripheral multifocal ground-glass opacities, linear opacities, reversed halo sign, and crazy-paving pattern are suggestive for coronavirus disease 2019 (COVID-19) in clinically suspicious cases, but they are not specific for the diagnosis, as other viral pneumonias, like influenza and some viral pneumonia may show similar imaging findings.

AIM

To find a specific imaging feature of the disease would be a welcome guide in diagnosis and management of challenging cases.

METHODS

Chest CT imaging findings of 650 patients admitted to a university Hospital in Tehran, Iran between January 2020 and July 2020 with confirmed COVID-19 infection by RT-PCR were reviewed by two expert radiologists. In addition to common non-specific imaging findings of COVID-19 pneumonia, radiologic characteristics of “pulmonary target sign” (PTS) were assessed. PTS is defined as a circular appearance of non-involved pulmonary parenchyma, which encompass a central hyperdense dot surrounded by ground-glass or alveolar opacities.

RESULTS

PTS were presented in 32 cases (frequency 4.9%). The location of the lesions in 31 of the 32 cases (96.8%) was peripheral, while 4 of the 31 cases had lesions both peripherally and centrally. In 25 cases, the lesions were located near the pleural surface and considered pleural based and half of the lesions (at least one lesion) were in the lower segments and lobes of the lungs. 22 cases had multiple lesions with a > 68% frequency. More than 87% of cases had an adjacent bronchovascular bundle. Ground-glass opacities were detectable adjacent or close to the lesions in 30 cases (93%) and only in 7 cases (21%) was consolidation adjacent to the lesions.

CONCLUSION

Although it is not frequent in COVID-19, familiarity with this feature may help radiologists and physicians distinguish the disease from other viral and non-infectious pneumonias in challenging cases.