CT imaging findings in lung transplant recipients with COVID-19

Abstract

Objectives: Our goal was to compare the chest computed tomography (CT) imaging findings of COVID-19 in lung transplant recipients (LTR) and a group of non-transplanted controls (NTC).

Methods: This retrospective study included 51 consecutive LTR hospitalized with COVID-19 from two centers. A total of 75 NTC were included for comparison. Images were classified regarding the standardized RSNA category, main pattern of lung attenuation, and longitudinal and axial distribution. Quantitative CT (QCT) analysis was performed to evaluate percentage of high attenuation areas (%HAA, threshold -250 to -700 HU). CT scoring was used to measure severity of parenchymal abnormalities.

Results: The imaging findings of COVID-19 in LTR were significantly different from controls regarding the RSNA classification and pattern of lung attenuation. LTR had a significantly higher proportion of patients with an indeterminate pattern on CT (0.31 vs. 0.11, p = 0.014). The most frequent pattern of attenuation in LTR was predominantly consolidation (0.39 vs. 0.22, p = 0.144) followed by a mixed pattern of ground-glass opacities (GGO) and consolidation (0.37 vs. 0.20, adjusted p = 0.102). On the other hand, the most common pattern in NTC was GGO predominant (0.58 vs. 0.24 of LTR, p = 0.001). LTR had significantly more severe parenchymal disease measured by CT score and %HAA by QCT (0.372 ± 0.08 vs. 0.148 ± 0.06, p < 0.001).

Conclusion: The most frequent finding of COVID-19 in LTR is a predominant pattern of consolidation. Compared to NTC, LTR more frequently demonstrated an indeterminate pattern according to the RSNA classification and more extensive lung abnormalities on QCT and semi-quantitative scoring.

Key points: • The most common CT finding of COVID-19 in LTR is a predominant pattern of consolidation followed by a mixed pattern of GGO and consolidation, while controls more often have a predominant pattern of GGO. • LTR more often presents with an indeterminate pattern of COVID-19 by RSNA classification than controls; therefore, molecular testing for COVID-19 is essential for LTR presenting with lower airway infection independently of imaging findings. • LTR had more extensive disease by semi-quantitative CT score and increased percentage areas of high attenuation on QCT.

Keywords: COVID-19; Computed tomography; Lung transplant; Quantitative CT.

Fig. 1

A 55-year-old woman presenting with history of fever and cough. A, B Axial CT and threshold-based reconstruction demonstrates a consolidation pattern (pink) with adjacent ground-glass opacities (orange) in a random axial distribution. C, D Coronal CT and quantitative CT reconstruction depicts the lower lobe predominance of the opacities in this patient

Fig. 2

A 44-year-old male with history of lung transplantation presenting with hypoxia. A Axial CT scan demonstrates a mixed pattern of ground-glass opacities and consolidation with diffuse axial distribution. B Threshold-based volumetric reconstruction shows the diffuse longitudinal distribution, right greater than left, as well as the areas of ground-glass opacities (orange), consolidation (pink), and normal lung (blue)

Fig. 3

A 61-year-old man with bilateral lung transplant presenting with shortness of breath for 6 days. A Axial CT demonstrates a predominant pattern of ground-glass opacities in a diffuse axial distribution, left greater than right. B, C Coronal CT and threshold-based reconstruction depicts the preferential involvement of the lower lobes, as well as the higher proportion of ground-glass opacities (orange) compared to consolidation (pink)