Persistent lung and vascular inflammation in mild to moderate COVID-19 survivors detected by ¹⁸F-FDG PET/CT… 2025, Verma+

[SNT Gatchaman]

Persistent lung and vascular inflammation in mild to moderate COVID-19 survivors detected by ¹⁸F-FDG PET/CT: A quantitative imaging study with implications for cardiovascular risk

Spoiler: Authors/Australia

Verma, Shipra; Lan, Nick S R; Espedal, Heidi; Ong, Jeremy; Roy, Ambuj; Ahmad, Adilah; Ali, Kamar; Ward, Natalie C; Patel, Sanjay; Parizel, Paul M; Francis, Roslyn J; Dwivedi, Girish

PURPOSE
Lingering inflammation after COVID-19 has been proposed as a contributor to long-term cardiovascular risk, yet the link between pulmonary and vascular inflammation remains insufficiently defined. This study aimed to quantify residual lung and vascular inflammation in individuals recovered from mild-to-moderate COVID-19 using ¹⁸F-FDG PET/CT and assess their association.

METHODS
Fifty-nine participants underwent ¹⁸F-FDG PET/CT imaging at a median of 97 days (IQR: 77–112.5) following clinical recovery from COVID-19. Lung inflammation was assessed using standardised uptake value maximum (SUVmax), target-to-background ratio maximum and mean (TBRmax, TBRmean), and total lung glycolysis (TLG) in contracted lung volumes to reduce spill-in from mediastinal structures. Metrics were indexed to blood pool activity (TBR) and lung volume (TLGindex). Vascular inflammation was evaluated using TBRmax values of the thoracic aorta and the most diseased segment (MDS). Results were compared with eight COVID-naive individuals using identical protocols.

RESULTS
Compared with controls, individuals post-COVID-19 exhibited significantly elevated SUVmax in both lungs (p < 0.001), TBRmax in the left (p = 0.037) and right (p = 0.010) lungs, and TLG in the left lung (p = 0.018). Measures of vascular inflammation correlated significantly with TBRmax, TBRmean, and TLGindex in both lungs (all p < 0.05), suggesting a parallel inflammatory response.

CONCLUSION
Persistent pulmonary inflammation is evident following mild-to-moderate COVID-19 and is associated with increased vascular inflammation. These findings suggest a mechanistic link between post-infectious lung and vascular inflammation, potentially contributing to elevated cardiovascular risk. ¹⁸F-FDG PET/CT enabled sensitive detection of subclinical inflammation in both compartments, highlighting the value of quantitative PET metrics in elucidating systemic inflammatory response following viral infection.

Web | DOI | PDF | European Journal of Nuclear Medicine and Molecular Imaging | Open Access

 

[SNT Gatchaman]

individuals symptomatically recovered from mild-to-moderate COVID-19 were prospectively recruited

Control participants underwent PET/CT imaging as part of a previously published, prospective mechanistic study that investigated arterial inflammation in individuals with elevated Lp(a) [19]. ¹⁸F-FDG PET/CT scans were performed for research purposes, as these individuals were asymptomatic and did not have any known acute illnesses, infections or any chronic inflammatory states. All scans were performed with identical protocols for extended fasting, uptake time, image acquisition parameters, and analysis techniques.

Multiple-comparison corrections were not applied to the correlations between lung and vascular uptake metrics because the analyses were hypothesis-driven and prespecified. Given the interdependence of the lung metrics, Bonferroni adjustments would have been overly conservative, reducing statistical power without materially decreasing the likelihood of false-positive findings. A two-tailed p-value of < 0.05 was considered statistically significant.

To our knowledge, this is the first study to quantify lung inflammation in individuals who have clinically recovered from mild-to-moderate COVID-19 using 18F-FDG PET/CT, the most sensitive imaging modality for assessing inflammation

Our findings demonstrate that lung inflammation persists for several months following mild to moderate COVID-19, extending beyond the previously described acute and early recovery phases. […] Median of vascular FDG uptake in our cohort (SUVmax 3.12; TBR max 2.68) remained consistently elevated relative to the blood pool, reflecting persistent low-grade arterial inflammation. Comparable values from both global and focal analyses reinforce the robustness of these findings and align with our prior report of heightened vascular uptake in COVID-19 survivors. Importantly, this new analysis demonstrates strong positive correlations between lung and vascular inflammation, suggesting that the ongoing lung inflammatory response may reflect broader systemic inflammatory activity and could represent a potential mechanism underlying the increased CV risk reported postCOVID

It is important to note that PET-based quantification of inflammation is not currently intended for routine clinical use but serves as a valuable research tool to elucidate systemic inflammatory responses and guide future biomarker development.

As this was a proof-of-concept study with a cross-sectional design, a causal relationship between lung and vascular inflammation could not be established.

 

[Utsikt]

This study found uptake of the tracer in lymph and spleen long after a covid vaccination:

We present a case of a patient with esophageal carcinoma who had 18F-FDG PET/CT scan, 8 weeks following booster dose of Moderna COVID-19 vaccination, which showed widespread FDG avid reactive lymph nodes and intense splenic uptake for prolonged duration of approximately 8 months (34 weeks) probably representing generalized immune response.

https://www.sciencedirect.com/science/article/pii/S1930043323002765

This found uptake in lymph nodes after flu vaccination:

We report on a 59-year-old female patient with an infected vascular graft investigated with 18F FDG-PET/CT. The first of two studies showed FDG activity in the left deltoid and ipsilateral axillary lymph nodes explained by influenza vaccination the day prior. The second 18F FDG-PET/CT showed multiple FDG-avid lymph nodes on both sides of the diaphragm without tracer accumulation at the vaccination site. Three months later the CT was negative for lymphadenopathy within the chest or abdominal region.

Generalized lymph node activation after Influenza vaccination on 18F FDG-PET/CT imaging, an important pitfall in PET interpretation

We report on a 59-year-old female patient with an infected vascular graft investigated with 18F FDG-PET/CT. The first of two studies showed FDG activity in the left deltoid and ipsilateral axillary lymph nodes explained by influenza vaccination the day prior. The second 18F FDG-PET/CT showed...

aojnmb.mums.ac.ir

Some vascular uptake detected after a woman experienced symptoms after covid vaccination:

The patient presented with complaints of cephalgia, cervicalgia, ostealgia, and pain in multiple large joints and muscles that started 2–3 weeks after the first shot of the Moderna COVID-19 vaccine (mRNA-1273) — which usually may cause mild side effects [4] — and worsened after the second shot. She never experienced anything alike before and denied any recent infection or new medication. Blood tests showed elevated erythrocyte sedimentation rate and C-reactive protein.

[18F]FDG-PET/CT demonstrated increased tracer uptakes in the large arteries of the legs (blue arrows in a). Additionally, we noted moderate enhancement within pelvic bursae (green arrows in a and b), along with intense FDG uptakes of the ligamenta flava (red arrows in b) and thoracolumbal interspinous bursae (blue arrows in b). There was significant enhancement in the V3 segment of the vertebral arteries (blue arrows in c), which correlated with arterial wall thickening on ceCT (blue arrows in d).

Vasculitis and bursitis on [18F]FDG-PET/CT following COVID-19 mRNA vaccine: post hoc ergo propter hoc? - European Journal of Nuclear Medicine and Molecular Imaging

link.springer.com

So nothing about lungs or heart from my quick googling, perhaps making it more likely that the observed differences are due to the covid infection?