Organizing pneumonia of COVID-19: Time-dependent evolution and outcome in CT findings

Abstract

Background As a pandemic, a most-common pattern resembled organizing pneumonia (OP) has been identified by CT findings in novel coronavirus disease (COVID-19). We aimed to delineate the evolution of CT findings and outcome in OP of COVID-19. Materials and methods 106 COVID-19 patients with OP based on CT findings were retrospectively included and categorized into non-severe (mild/common) and severe (severe/critical) groups. CT features including lobar distribution, presence of ground glass opacities (GGO), consolidation, linear opacities and total severity CT score were evaluated at three time intervals from symptom-onset to CT scan (day 0–7, day 8–14, day > 14). Discharge or adverse outcome (admission to ICU or death), and pulmonary sequelae (complete absorption or lesion residuals) on CT after discharge were analyzed based on the CT features at different time interval. Results 79 (74.5%) patients were non-severe and 103 (97.2%) were discharged at median day 25 (range, day 8–50) after symptom-onset. Of 67 patients with revisit CT at 2–4 weeks after discharge, 20 (29.9%) had complete absorption of lesions at median day 38 (range, day 30–53) after symptom-onset. Significant differences between complete absorption and residuals groups were found in percentages of consolidation (1.5% vs. 13.8%, P = 0.010), number of involved lobe > 3 (40.0% vs. 72.5%, P = 0.030), CT score > 4 (20.0% vs. 65.0%, P = 0.010) at day 8–14. Conclusion Most OP cases had good prognosis. Approximately one-third of cases had complete absorption of lesions during 1–2 months after symptom-onset while those with increased frequency of consolidation, number of involved lobe > 3, and CT score > 4 at week 2 after symptom-onset may indicate lesion residuals on CT.

Profiling of the immune repertoire in COVID-19 patients with mild, severe, convalescent, or retesting-positive status

“…After treatment, the SARS-CoV-2 load in the body is reduced greatly, viral NAT is negative, and the patient enters a long convalescence period with slow repair of tissue damage [ 8 , 25 ]. Some convalescent patients with a weak immune response after SARS-CoV-2 infection are positive for SARS-CoV-2 NAT, which harbors risks to the treatment and prevention of COVID-19 [ 17 , 18 ].…”

A Pictorial Review of the Role of Imaging in the Detection, Management, Histopathological Correlations, and Complications of COVID-19 Pneumonia

“…The reverse halo sign is reported by some authors in the later phase of the disease [ 28 , 136 ]. COVID-19 pneumonia shares a lot of CT features with OP, such as peripheral GGO, consolidation, or both in bilateral multifocal distribution, and reverse halo sign, and these features were also confirmed on histopathological examination [ 137 , 138 , 139 ]. To provide standardized communication, chest CT findings for COVID-19 pneumonia are currently classified as typical, indeterminate, and atypical [ 13 , 15 , 16 , 19 , 136 ].…”

“…In the progressive phase, if the patient’s immunity is low or there is no response to therapy, COVID-19 pneumonia can progress to ARDS [ 133 ]. In the absorption phase, lung alterations start to decrease and signs of fibrosis with fibrotic streaks, traction bronchiectasis, bronchial distortion, and subpleural fibrotic line can be predominant [ 28 , 109 , 133 , 135 , 138 ].…”

COVID-19 Associated Pneumonia

“…9-11,19-21, 26,27,30-34,36,37 Other rare findings reportedly include organising pneumonia and both reversed halo and halo signs; however, such features have been reported in only a few case series and are not specific to COVID-19 associated pneumonia. [43][44][45] The underlying pathological mechanism of such findings is unclear; however, it is thought that they represent the healing process of lung injuries related to COVID-19 infection.…”