Long COVID hallmarks on [18F]FDG-PET/CT: a case-control study

Abstract

Purpose The present study hypothesised that whole-body [18F]FDG-PET/CT might provide insight into the pathophysiology of long COVID. Methods We prospectively enrolled 13 adult long COVID patients who complained for at least one persistent symptom for >30 days after infection recovery. A group of 26 melanoma patients with negative PET/CT matched for sex/age was used as controls (2:1 control to case ratio). Qualitative and semi-quantitative analysis of whole-body images was performed. Fisher exact and Mann-Whitney tests were applied to test differences between the two groups. Voxel-based analysis was performed to compare brain metabolism in cases and controls. Cases were further grouped according to prevalent symptoms and analysed accordingly. Results In 4/13 long COVID patients, CT images showed lung abnormalities presenting mild [18F]FDG uptake. Many healthy organs/parenchyma SUVs and SUV ratios significantly differed between the two groups ( p ≤ 0.05). Long COVID patients exhibited brain hypometabolism in the right parahippocampal gyrus and thalamus (uncorrected p < 0.001 at voxel level). Specific area(s) of hypometabolism characterised patients with persistent anosmia/ageusia, fatigue, and vascular uptake (uncorrected p < 0.005 at voxel level). Conclusion [18F]FDG PET/CT acknowledged the multi-organ nature of long COVID, supporting the hypothesis of underlying systemic inflammation. Whole-body images showed increased [18F]FDG uptake in several “target” and “non-target” tissues. We found a typical pattern of brain hypometabolism associated with persistent complaints at the PET time, suggesting a different temporal sequence for brain and whole-body inflammatory changes. This evidence underlined the potential value of whole-body [18F]FDG PET in disclosing the pathophysiology of long COVID. Supplementary Information The online version contains supplementary material available at 10.1007/s00259-021-05294-3.

Long COVID-19 Syndrome: A Comprehensive Review of Its Effect on Various Organ Systems and Recommendation on Rehabilitation Plans

“…This has been similarly observed in other pandemics [119]. The hypometabolism in parahippocampal gyrus, thalamus, and some white matter may be a secondary result of hypoxic damage to these areas, leading to memory loss and cognitive dysfunctions [120].…”

The Post-Acute Phase of SARS-CoV-2 Infection in Two Macaque Species Is Associated with Signs of Ongoing Virus Replication and Pathology in Pulmonary and Extrapulmonary Tissues

“…This finding in a recognized NHP model for COVID-19 research is of particular interest because of the growing concern for long-COVID in humans [ 60 ]. More than a year after the start of the pandemic, it is evident that humans can suffer from COVID-19-related symptoms, weeks to months after seemingly resolving the infection [ 5 , 6 , 7 ].…”

“…Then, a convalescent phase is initiated during which the infection resolves, and patients recover from the disease. Nevertheless, evidence is accumulating for the existence of an enlengthened recovery process, even for non-hospitalized patients [ 5 , 6 , 7 ]. Moreover, in this phase, chronic symptoms and possible recurrence of disease can be detected, known as long-COVID or post-acute COVID [ 7 , 8 ].…”

A Review of Neurological Involvement in Patients with SARS-CoV-2 Infection

“…Long COVID patients (with at least 1 long-lasting symptom more than 1 month after recovery) presented with a lower metabolization rate in the right parahippocampal gyrus and thalamus than in melanoma controls. It is noteworthy that the hypometabolism in these brain regions was similar to that of subjects with long-lasting fatigue and anosmia/ageusia [ 97 ]. Although there are relatively few reports on patients with long COVID, considering the large scale of the pandemic, there could be many COVID-19 patients with persistent neurological issues.…”