FDG PET Findings Post-COVID Vaccinations: Signs of the Times?

SARS-CoV-2 Affects Thyroid and Adrenal Glands: An 18F-FDG PET/CT Study

BACKGROUND

Since most endocrine glands express ACE-2 receptors and can be infected by SARS-CoV-2 virus, this retrospective multicentre observational study aims to assess the metabolic activity of thyroid and adrenal glands of COVID-19 patients by 18F-FDG PET/CT.

METHODS

We retrospectively evaluated the 18F-FDG PET/CT scans of COVID-19 patients admitted by three different centres, either in a low-intensity department or in the intensive care unit (ICU). A visual assessment and a semi-quantitative evaluation of areas of interest in thyroid and adrenal glands were performed by recording SUVmax and SUVmean. The 18F-FDG PET/CT uptake in COVID-19 patients was compared with those observed in normal age-matched controls.

RESULTS

Between March 2020 and March 2022, 33 patients from three different centres (twenty-eight patients in a low-intensity department and five patients in ICU), were studied by 18F-FDG PET/CT during active illness. Seven of them were also studied after clinical remission (3-6 months after disease onset). Thirty-six normal subjects were used as age-matched controls. In the thyroid gland, no statistically significant differences were observed between control subjects and COVID-19 patients at diagnosis. However, at the follow-up PET/CT study, we found a statistically higher SUVmax and SUVmean (p = 0.009 and p = 0.004, respectively) in the thyroid of COVID-19 patients. In adrenal glands, we observed lower SUVmax and SUVmean in COVID-19 patients at baseline compared to control subjects (p < 0.0001) and this finding did not normalize after clinical recovery (p = 0.0018 for SUVmax and p = 0.002 for SUV mean).

CONCLUSIONS

In our series, we observed persistent low 18F-FDG uptake in adrenal glands of patients at diagnosis of COVID-19 and after recovery, suggesting a chronic hypofunction. By contrast, thyroid uptake was comparable to normal subjects at disease onset, but after recovery, a subgroup of patients showed an increased metabolism, thus possibly suggesting the onset of an inflammatory thyroiditis. Our results should alert clinicians to investigate the pituitary-adrenal axis and thyroid functionality at the time of infection and to monitor them after recovery.

Lymphadenopathy subsequent to Covishield (ChAdOx1 nCoV-19) Corona virus vaccine: ultrasound findings and clinical implications

Introduction

Post anti-COVID-19 vaccine lymphadenopathies have been recently described in literature, from different parts of the world. Although there have been studies on lymphadenopathy following mRNA vaccines, there is a paucity of studies on lymphadenopathy following inactivated viral vaccines, such as Covishield.

Aim

In this study, we explored lymphadenopathy subsequent to Covishield vaccine in terms of its various ultrasound parameters in the Indian population.

Methods

This hospital-based longitudinal study was conducted among 50 adult beneficiaries of Covishield vaccine. Sociodemographic details and relevant clinical history were recorded using a semi-structured performa. Detailed ultrasound (USG) examination of the bilateral axillae was done on the day of vaccination and after 6-12 days post vaccination. Vaccine beneficiaries were evaluated for the presence of any vaccine-associated lymphadenopathy and described the presence, number, size, morphology, cortical thickness, and presence or absence of echogenic hilum.

Results

Out of total (63) lymph nodes evaluated sonologically, majority (80.9%) of lymph nodes showed the features of benign lymphadenopathy. However, 12.6% (8/63) lymph nodes showed diffusely thickened cortex with preserved central echogenic hilum, 4.76% (3/63) lymph nodes showed eccentric cortical thickness with preserved hilar pattern, while only one lymph node showed diffuse cortical thickening with loss of central echogenic hilum.

Conclusion

With an increase in vaccination coverage, clinicians are likely to confront increasing cases of vaccine-associated axillary lymphadenopathy. Therefore, they should exercise care, that contemporary anti-COVID-19 vaccination can present an aetiology of axillary lymph nodes with suspicious USG features.

Lymphadenopathy post-COVID-19 vaccination with increased FDG uptake may be falsely attributed to oncological disorders: A systematic review

Coronavirus disease 2019 (COVID-19) has caused a global pandemic that continues to cause numerous deaths to date. Four vaccines have been approved by the Food and Drug Administration as of July 2021 to prevent the transmission of COVID-19: Pfizer, Moderna, AstraZeneca, and Janssen. These vaccines have shown great efficacy and safety profile. One side effect that has been widely reported is post-COVID-19 vaccination lymphadenopathy. Due to the mimicry of the lymphadenopathy for metastases in some oncologic patients, there have been reports of patients who underwent biopsies that showed pathologic confirmation of benign reactive lymphadenopathy secondary to the COVID-19 vaccine. Therefore, understanding the incidence of lymphadenopathy post-COVID-19 vaccinations will help guide radiologists and oncologists in their management of patients, both present oncologic patients, and patients with concerns over their newly presenting lymphadenopathy. A systematic literature search was performed using several databases to identify relevant studies that reported lymphadenopathy post-COVID-19 vaccination. Our results revealed that several cases have been detected in patients undergoing follow-up fluorodeoxyglucose (FDG)-positron emission tomography-computerized tomography scans where lymph nodes ipsilateral to the vaccine injection site show increased uptake of FDG. Thus, knowledge of the incidence of lymphadenopathy may help avoid unnecessary biopsies, interventions, and changes in management for patients, especially oncologic patients who are at risk for malignancies.

Subdiaphragmatic Lymph Nodes Uptake on 18F-FDG PET/CT After COVID-19 Vaccination in the Thigh

ABSTRACT

Since worldwide COVID-19 vaccination, 18F-FDG uptake in reactive axillary lymph nodes has been frequently observed in PET/CT studies. We describe a patient with breast cancer who underwent 18F-FDG PET/CT 7 days after receiving COVID-19 vaccination in the right thigh. 18F-FDG uptake was observed in nonenlarged right-sided inguinal, iliac, and para-aortic lymph nodes. As the thigh can be used as an alternate site for COVID-19 vaccine injection in case of lymphedema in both arms or for adequate axillary staging in patients with breast cancer, physicians should be aware of such 18F-FDG uptake pattern.

COVID-19 Vaccination-Associated Lymphadenopathy on FDG PET/CT: Distinctive Features in Adenovirus-Vectored Vaccine

PURPOSE

This study investigated 18F-FDG PET/CT features of adenovirus-vectored vaccination against COVID-19 in healthy subjects.

PATIENTS AND METHODS

Thirty-one health care workers had been vaccinated Vaxzevria and underwent FDG PET/CT as an optional test for a cancer screening program. Size and FDG uptake of the hypermetabolic lymph nodes were measured. Uptake value of spleen was also measured with liver for comparison.

RESULTS

All examinees who underwent FDG PET/CT within 14 days' interval showed hypermetabolic lymphadenopathies ipsilateral to vaccine injection. All examinees with hypermetabolic lymphadenopathy had simultaneous muscular uptakes until 23 days' interval. Among 12 examinees who underwent FDG PET/CT more than 15 days after vaccination, only 3 male examinees did not show hypermetabolism in the axillary lymph nodes. There was no female examinee with negative hypermetabolic lymphadenopathy until 29 days after vaccination.

CONCLUSIONS

Hypermetabolic reactive lymphadenopathy in the ipsilateral axillary area with or without supraclavicular area is most likely to occur in a healthy person with recent adenovirus-vectored COVID-19 vaccination on FDG PET/CT.

Lymphadenopathy Following COVID-19 Vaccination: Imaging Findings Review

RATIONALE AND OBJECTIVES

Despite all the benefits and effectiveness of the coronavirus disease 2019 (COVID-19) vaccines mentioned in recent clinical trials, some post-vaccination side effects such as lymphadenopathy (LAP) were observed. The present study reviewed all studies with imaging findings presentation of LAP after COVID-19 vaccination.

MATERIALS AND METHODS

We conducted a literature search in online databases, including Scopus, Medline (PubMed), Web of Science, Embase (Elsevier), Cochrane library, and Google Scholar.

RESULTS

A total of 19 studies (68 cases), including 60 (88.2%) females and eight (11.8%) males with a presentation of LAP after COVID-19 vaccination, were reviewed. LAP was identified after first or second dosages of three types of COVID-19 vaccines, including Pfizer-BioNTech (n = 30, 44.1%), Moderna (n = 17, 25%), and Oxford-AstraZeneca (n = 1, 1.5%). In 20 (29.4%) cases, vaccine type was not reported or only reported as mRNA COVID-19 vaccine. The median days of LAP presentation after the first and second dosages of COVID-19 vaccination, were 12 and 5 days, respectively. Most of the LAP imaging findings related to COVID-19 vaccination (n = 66, 97%) were seen from first day to 4 weeks after vaccination. However, LAP remained after 5 and 6 weeks of the first and second dosages of COVID-19 vaccination with decreased lymph nodes' size and residual cortical thickening in two cases.

CONCLUSION

This review study of cases with LAP-associated COVID-19 vaccination guides radiologists and physicians to rely on patient's clinical context and updated resources to prevent potential disease upstaging and change in therapy.

COVID-19 vaccine-related axillary lymphadenopathy in breast cancer patients: Case series with a review of literature

PURPOSE

Lymphadenopathy (LAP) after COVID-19 vaccination in patients with a diagnosis of cancer has been challenging. We analyzed imaging and clinical features from early cases of axillary LAP in six COVID-19 vaccine recipients with a history of breast cancer.

METHOD

Among the patients with a history of breast cancer and recent COVID-19 vaccine administration, six patients who showed isolated axillary LAP were gathered. Radiologic features were reviewed from breast ultrasound, chest computed tomography, and breast magnetic resonance imaging. Clinical and pathological information were obtained for analysis.

RESULTS

The interval between ultrasound detection of LAP and last COVID-19 vaccine administration ranged from 14 to 28 days (mean 21.67 days). Round shape of the lymph node and irregular cortex were noted in 2 and 0 cases, respectively. Mean maximum cortical thickness, length to width ratio and interval aggravation in maximum cortical thickening were 4.2 mm, 1.34, and 2.81-fold with cut-off value of 3 mm, 1.5, 2.0-fold, respectively.

CONCLUSION

We observed axillary LAP ipsilateral to a recent vaccine administration persisting longer than what the Centers for Disease Control and Prevention announced. In our patients, COVID-19 vaccine-related LAP tended to show increased cortical thickness without cortical irregularity. Oncologist as well as radiologist should be familiar with the fact that COVID-19 vaccines, regardless of vaccine type or dosage, can frequently cause ipsilateral axillary LAP, showing some suspicious features more often than others, and can persist longer than anticipated so that both over- and underdiagnosis can be avoided. We report our observations in six patients and provide an exhaustive review of the published literature.

Correlation between BNT162b2 mRNA Covid-19 vaccine-associated hypermetabolic lymphadenopathy and humoral immunity in patients with hematologic malignancy

Purpose

Vaccine-associated hypermetabolic lymphadenopathy (VAHL) is frequently observed on [¹⁸F]FDG PET-CT following BNT162b2 administration. Recent data suggest a prominent B cell germinal-center (GC) response elicited by mRNA vaccines in draining lymph nodes. Thus, in this study we aimed to explore the correlation between VAHL and humoral immunity as reflected by post-vaccination serologic testing and by comparing the incidence of VAHL between lymphoma patients treated recently with B cell depleting therapy and those that were not.

Methods

A total of 137 patients with hematologic malignancy that had post-vaccination [¹⁸F]FDG PET-CT were included (All-PET group), 86 received both vaccine doses before imaging (PET-2 group). Their VAHL status and grade on imaging were recorded. Among 102 lymphoma patients, 34 (33.3%) were treated during the year prior vaccination with anti-CD20 antibody containing therapy. A subgroup of 54 patients also underwent serologic testing 2–3 weeks after the booster dose, and their anti-spike titers were recorded and graded as well.

Results

The overall incidence of VAHL in patients with hematologic malignancy was 31.4%. The 34 lymphoma patients treated during the year prior vaccination with anti-CD20 antibody containing therapy had significantly lower rates of VAHL comparted with all other lymphoma patients (8.8 versus 41.2% in all-PET patients, Pv < 0.01). VAHL rates were 10% in patients with negative serology, 31.3% in patients with low anti-spike titers, and 72.2% in patients with high anti-spike titers. The positive predictive values of VAHL were 90 and 93.3% in all-PET and PET-2 patients, respectively. A positive statistically significant correlation was found between VAHL and serology ranks in All-PET patients (r_s = 0.530, Pv < 0.001), and stronger correlation was found in PET-2 patients (r_s = 0.642, Pv < 0.001).

Conclusion

VAHL on [¹⁸F]FDG PET-CT of patients with hematologic malignancy may reflect GC B cell proliferation and an effective humoral response elicited by BNT162b2 vaccine.