Pulmonary circulation abnormalities in post-acute COVID-19 syndrome: dual-energy CT angiographic findings in 79 patients, 2023, Mohamed et al.

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Pulmonary circulation abnormalities in post-acute COVID-19 syndrome: dual-energy CT angiographic findings in 79 patients
Mohamed, Islam; de Broucker, Virginie; Duhamel, Alain; Giordano, Jessica; Ego, Alice; Fonne, Nicolas; Chenivesse, Cécile; Remy, Jacques; Remy-Jardin, Martine

Objectives
To evaluate the frequency and pattern of pulmonary vascular abnormalities in the year following COVID-19.

Methods
The study population included 79 patients remaining symptomatic more than 6 months after hospitalization for SARS-CoV-2 pneumonia who had been evaluated with dual-energy CT angiography.

Results
Morphologic images showed CT features of (a) acute (2/79; 2.5%) and focal chronic (4/79; 5%) PE; and (b) residual post COVID-19 lung infiltration (67/79; 85%). Lung perfusion was abnormal in 69 patients (87.4%). Perfusion abnormalities included (a) perfusion defects of 3 types: patchy defects (n = 60; 76%); areas of non-systematized hypoperfusion (n = 27; 34.2%); and/or PE-type defects (n = 14; 17.7%) seen with (2/14) and without (12/14) endoluminal filling defects; and (b) areas of increased perfusion in 59 patients (74.9%), superimposed on ground-glass opacities (58/59) and vascular tree-in-bud (5/59). PFTs were available in 10 patients with normal perfusion and in 55 patients with abnormal perfusion. The mean values of functional variables did not differ between the two subgroups with a trend toward lower DLCO in patients with abnormal perfusion (74.8 ± 16.7% vs 85.0 ± 8.1).

Conclusion
Delayed follow-up showed CT features of acute and chronic PE but also two types of perfusion abnormalities suggestive of persistent hypercoagulability as well as unresolved/sequelae of microangiopathy.

Clinical relevance statement
Despite dramatic resolution of lung abnormalities seen during the acute phase of the disease, acute pulmonary embolism and alterations at the level of lung microcirculation can be identified in patients remaining symptomatic in the year following COVID-19.

Key Points
• This study demonstrates newly developed proximal acute PE/thrombosis in the year following SARS-CoV-2 pneumonia.
• Dual-energy CT lung perfusion identified perfusion defects and areas of increased iodine uptake abnormalities, suggestive of unresolved damage to lung microcirculation.
• This study suggests a complementarity between HRCT and spectral imaging for proper understanding of post COVID-19 lung sequelae.

Link | PDF (European Radiology)

 

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Hospitalised patients.

To our knowledge, this is the first study providing detailed analysis of morpho-functional changes at the level of the pulmonary circulation in patients with persistent symptoms more than 6 months after recovery from COVID-19. At the time of this delayed CT follow-up, all patients had a dramatic resolution of the radiographic features of COVID-19 pneumonia with a complete clearing of lungs in 12 patients (15%) and residual findings in 67 patients (85%) with a median COVID-19 CT score decreasing from 45.4 to 1.18%.

Commentary: Pulmonary vasculopathy in post-acute-COVID-19 syndrome—insights from dual-energy CT angiography —

They identify a spectrum of perfusion abnormalities in patients with post-acute COVID-19 syndrome which may reflect dysregulated vascular repair post-infection and build on the concept that post-COVID vasculopathy may significantly contribute to persistent symptomatic disease with limited or no residual morphological findings on CT.

Evidence supporting vascular dysfunction is widely described in acute COVID-19 disease both from autopsy studies showing vasculocentric distribution, endothelial injury, microthrombosis and new vessel formation, and from morphologic CT imaging. [...] The dilated vessel sign and vascular tree in the bud were described as novel morphological CT findings in acute COVID with potential diagnostic utility in indeterminate cases in the case of the former and potential prognostic value in the case of the latter. Although the pathological correlation of these CT signs is unclear, they are generally considered to represent an imaging correlate of pulmonary thrombotic angiopathy.

The key findings relate to the analysis of the perfusion images which showed abnormal perfusion in 87.4%. [...] The authors hypothesise that patchy perfusion defects relate to microvascular thrombi at the level of capillaries while PE-type defects are the sequela of organised thrombi in small pulmonary arterial branches (1–2 mm).

Intriguingly, focal hyper-perfusion was seen in 74.9% of patients and was always in areas of parenchymal abnormality—typically ground glass opacity or band-like opacity but also areas of vascular tree in the bud. Authors hypothesise that this may relate to angiogenesis at the level of pulmonary capillaries and vascular remodelling with bronchopulmonary anastomoses which is supported by the observation of pulmonary capillary haemangiomatosis-like changes pathologically in post-COVID syndrome.

 

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Dr Graham Lloyd-Jones tweets on this paper —

https://threadreaderapp.com/thread/1687219768523190272.html

Post-acute symptoms should be taken seriously. Imaging may not be informative, but this is not the patient's fault - the medical imaging is letting us and them down

Rule #1
If your patient has persistent symptoms post acute COVID, then please believe them

Rule #2
Imaging has a limited role and normal imaging should not be taken to mean there is no problem

Rule #3
Perfusion scanning is probably best for those with persistent respiratory symptoms

Rule #4
Believing your patient is more important than imaging
(It's the old adage: Treat your patient, not the imaging!)