CT findings of COVID-19 in follow-up: comparison between progression and recovery

Abstract

We aimed to retrospectively analyze the imaging changes detected in the follow-up of coronavirus disease 2019 (COVID-19) patients on thin-section computed tomography (CT). METHODSWe included 54 patients diagnosed with COVID-19. The mean interval between the initial and follow-up CT scans was 7.82±3.74 days. Patients were divided into progression and recovery groups according to their outcomes. We evaluated CT images in terms of distribution of lesions and imaging manifestations. The manifestations included ground-glass opacity (GGO), crazy-paving pattern, consolidation, irregular line, and air bronchogram sign. RESULTSCOVID-19 lesions showed mainly subpleural distribution, which was accompanied by bronchovascular bundle distribution in nearly 30% of the patients. The lower lobes of both lungs were the most commonly involved. In the follow-up, the progression group showed more involvement of the upper lobe of the left lung than the recovery group. GGO was the most common sign. As the disease progressed, round GGO decreased and patchy GGO increased. On follow-up CT, consolidation increased in the progression group while decreasing in the recovery group. Air bronchogram sign was more commonly observed at the initial examination (90.9%) than at follow-up (30%) in the recovery group, but there was no significant change in the progression group. Pleural effusion and lymphadenopathy were absent in the initial examination, but pleural effusion was observed in three cases after follow-up. CONCLUSIONAs COVID-19 progressed, round GGOs tended to evolve into patchy GGOs, consolidation increased, and pleural effusion could be occasionally observed. As COVID-19 resolved, the crazy-paving pattern and air bronchogram significantly decreased.

Liver function recovery of COVID-19 patients after discharge, a follow-up study

“…One of the main purposes of follow-up is to monitor nucleic acid reactivation. Although the current evidences suggest that positivity on follow-up RT-PCR not imply infectivity [22], typical symptoms occur in a significant proportion of recurrence patients and require further treatment [23][24][25]. On the other hand, it is imperative to understand the possible outcome of discharged COVID-19 patients, especially if they have any other detrimental illnesses by longitudinal analysis to safeguard their life in future [26,27].…”

Contribution of CT Features in the Diagnosis of COVID-19

“…With the progression of the disease, the appearance of the typical round GGOs decreases, but the appearance of patchy GGOs and consolidations increases. We therefore hypothesize that the appearance of GGOs together with other signs may indicate disease progression and the worsening of lung injury [ 53 ].…”

“…The appearance of air bronchogram, represented by a pattern of “air-filled bronchi” with low attenuation, was observed on a background of high-density parenchyma without air [ 30 ] ( Figure 2(a) ). This sign is also a common CT finding recorded in a series of cases of COVID-19 [ 32 , 48 ], which appears frequently in the progressive stage or the peak stage (4–14 days after the onset of the initial symptoms) [ 33 , 53 ] and sometimes in the early stage [ 34 ]. However, the term of “air bronchogram” appears to be inaccurate owing to the low density of the mucus in the bronchi, which is akin to a gelatinous mucus plug rather than air.…”

“…Based on the published literature, the most common CT findings in the initial and early stage were GGO and consolidation, including patchy/punctate ground-glass opacities, and most of the GGOs progressed to multiple ground-glass infiltration in the lungs, and the consolidation became more serious in more cases in the progressive, late, or the follow-up stages. The other accompanied features included crazy-paving pattern, interstitial thickening or reticulation, air bronchograms, pleural effusion, and fibrous strips [ 8 , 10 , 31 , 34 , 50 , 53 , 55 ].…”

Tomographic findings in patients with COVID-19 according to evolution of the disease

“…It occurs after 14 days of symptom onset and corresponds to disease control. Dissipation of the consolidation is observed; in the same way, it can be observed areas of opacities in ground glass that corresponds to regression areas, and there may also be scarring atelectasis, which indicates fibrosis [ 57 ]. As for this phase, the pattern in “crazy paving” is no longer present.…”