Radio-Histological Correlation of Lung Features in Severe COVID-19 Through CT-Scan and Lung Ultrasound Evaluation

Abstract

Background: Patients with coronavirus disease 2019 (COVID-19) can develop severe bilateral pneumonia leading to respiratory failure. Lung histological samples were scarce due to the high risk of contamination during autopsies. We aimed to correlate histological COVID-19 features with radiological findings through lung ultrasound (LU)-guided postmortem core needle biopsies (CNBs) and computerized tomography (CT) scans.

Methodology: We performed an observational prospective study, including 30 consecutive patients with severe COVID-19. The thorax was divided into 12 explorations regions to correlate LU and CT-scan features. Histological findings were also related to radiological features through CNBs.

Results: Mean age was 62.56 ± 13.27 years old, with 96.7% male patients. Postmortem LU-guided CNBs were performed in 13 patients. Thirty patients were evaluated with both thoracic LU and chest CT scan, representing a total of 279 thoracic regions explored. The most frequent LU finding was B2-lines (49.1%). The most CT-scan finding was ground-glass opacity (GGO, 29%). Pathological CT-scan findings were commonly observed when B2-lines or C-lines were identified through LU (positive predictive value, PPV, 87.1%). Twenty-five postmortem echo-guided histological samples were obtained from 12 patients. Histological samples showed diffuse alveolar damage (DAD) (75%) and chronic interstitial inflammation (25%). The observed DAD was heterogeneous, showing multiple evolving patterns of damage, including exudative (33.3%), fibrotic (33.3%), and organizing (8.3%) phases. In those patients with acute or exudative pattern, two lesions were distinguished: classic hyaline membrane; fibrin "plug" in alveolar space (acute fibrinous organizing pneumonia, AFOP). C-profile was described in 33.3% and presented histological signs of DAD and lung fibrosis. The predominant findings were collagen deposition (50%) and AFOP (50%). B2-lines were identified in 66.7%; the presence of hyaline membrane was the predominant finding (37.5%), then organizing pneumonia (12.5%) and fibrosis (37.5%). No A-lines or B1-lines were observed in these patients.

Conclusion: LU B2-lines and C-profile are predominantly identified in patients with severe COVID-19 with respiratory worsening, which correspond to different CT patterns and histological findings of DAD and lung fibrosis.

Keywords: COVID-19; biopsy; lung ultrasonography (LU); pathology; radiology.

Figure 1

Proportion of CT-scan findings in the function of LU images. CT scan, computerized tomography scan; LU, lung ultrasound; GGO, ground-glass opacity.

Figure 2

Examples of CNB. (A): AFOP-like DAD: (arrows: deposition of fibrin plugs filling the alveolar space); (B): AFOP-like organizing DAD (arrows: fibrin plugs deposited in the alveoli and focal organization changes in the interstitium); (C): AFOP-like fibrotic DAD [focal organizational changes (star), interstitial deposition of collagen (arrow) accompanied by pneumocyte type II hyperplasia (arrowhead)]. (D): Fibrotic DAD (arrows: thickening of the alveolar septa with mature collagen deposition in the interstitium). CNB, core needle biopsy; DAD, diffuse alveolar damage; AFOP, acute fibrinous organizing pneumonia.

Figure 3

Proportion of histological findings in function of LU images. AFOP, Acute Fibrinous Organizing Pneumonia; LU, Lung ultrasound.

Figure 4

LU–CT–histology from the same region. LU (A), CT-scan (B), and histological (C) images of the same patient. The LU exploration (A) shows a C-profile pattern, seen in the anterior left region of the thorax; CT scan (B) shows areas of ground-glass opacity in the same region. In the histological sample (C), we observe an AFOP-like fibrotic DAD (focal organizational changes, interstitial deposition of collagen accompanied by pneumocyte type II hyperplasia).