[18F]FDG uptake in axillary lymph nodes and deltoid muscle after COVID-19 mRNA vaccination: a cohort study to determine incidence and contributing factors using a multivariate analysis

Reactive axillary lymph nodes after COVID-19 mRNA vaccination: comparison of mRNA vs. attenuated whole-virus vaccines

OBJECTIVE

To compare the incidence and natural course of reactive axillary lymph nodes (RAL) between mRNA and attenuated whole-virus vaccines using Deauville criteria.

METHODS

In this multi-institutional PET-CT study comprising multiple vaccine types (Pfizer-BioNTech/Comirnaty, Moderna/Spikevax, Sinovac/CoronaVac and Janssen vaccines), we evaluated the incidence and natural course of RAL in a large cohort of oncological patients utilizing a standardized Deauville scaling system (n=522; 293 Female, Deauville 3-5 positive for RAL). Univariate and multivariate analyses were conducted to evaluate the predictive value of clinical parameters (absolute neutrophil count [ANC], platelets, age, sex, tumor type, and vaccine-to-PET interval) for PET positivity.

RESULTS

Pfizer-BioNTech/Comirnaty and Moderna vaccines revealed similar RAL incidences for the first 20 days after the second dose of vaccine administration (44% for the first 10 days for both groups, 26% vs. 20% for 10-20 days, respectively for Moderna and Pfizer). However, Moderna recipients revealed significantly higher incidences of RAL after 20 days compared to Pfizer-BioNTech/Comirnaty, with nodal reactivity spanning up to the 9th week post-vaccination (15% vs. 4%, respectively P  < 0.001). No RAL was observed in patients who received either a single dose of J&J vaccine or two doses of CroronaVac. Younger patients showed increased likelihood of RAL, otherwise, clinical/demographic parameters were not predictive of RAL ( P  = 0.014 for age, P  > 0.05 for additional clinical/demographic parameters).

CONCLUSION

RAL based on strict PET criteria was observed with mRNA but not with attenuated whole-virus vaccines, in line with higher immunogenicity and stronger protection offered by mRNA vaccines.

Examination of iatrogenic FDG accumulation after COVID-19 vaccination

PURPOSE

This study aimed to investigate the frequency of COVID-19 vaccine-induced reactive change and potential factors including blood type correlated with increased FDG uptake on positron emission tomography (PET)/computed tomography (CT).

MATERIALS AND METHODS

We evaluated 284 patients who underwent PET/CT between June and September 2021 and had a known history of COVID-19 vaccination. Information on the injection site, vaccine type, and adverse reactions was obtained. We visually assessed the presence or absence of accumulation in the axillary and supraclavicular lymph nodes and the deltoid muscles. We measured the maximum standardized uptake value (SUVmax) using semi-quantitative analysis.

RESULTS

Our study included 158 males and 126 females aged 16-94. The median time between vaccination and PET/CT was 9 and 42 days for patients who had received their first and second doses, respectively. We observed axillary lymph node accumulation, supraclavicular lymph node accumulation, and deltoid muscle accumulation in 98 (SUVmax 1.07-25.1), nine (SUVmax 2.28-14.5), and 33 cases (SUVmax 0.93-7.42), respectively. In cases with axillary lymph node (P = 0.0057) or deltoid muscle (P = 0.047) accumulation, the shorter the time since vaccination, the higher the FDG accumulation. Patients with axillary lymph node accumulation were significantly younger (P < 0.0001) and had a significantly higher frequency of adverse reactions such as fever (P < 0.0001) and myalgia (P = 0.002). No significant relationship was observed between blood type and the frequency of FDG accumulation. Logistic regression analysis also showed that age, gender, days since vaccination, and adverse reactions such as fever and myalgia were important factors for axillary lymph node accumulation.

CONCLUSION

Our study found that FDG accumulation in the axillary lymph nodes and deltoid muscle was higher within a shorter time after vaccination, and axillary lymph node accumulation was higher in young patients, females, and those with adverse reactions of fever and myalgia. No significant relationship was observed between blood type and the frequency of FDG accumulation. Confirming the vaccination status, time since vaccination, and the presence of adverse reactions before PET may reduce false positives.

FDG PET/CT Imaging 1 Week after a Single Dose of Pembrolizumab Predicts Treatment Response in Patients with Advanced Melanoma

PURPOSE

Immunologic response to anti-programmed cell death protein 1 (PD-1) therapy can occur rapidly with T-cell responses detectable in as little as one week. Given that activated immune cells are FDG avid, we hypothesized that an early FDG PET/CT obtained approximately 1 week after starting pembrolizumab could be used to visualize a metabolic flare (MF), with increased tumor FDG activity due to infiltration by activated immune cells, or a metabolic response (MR), due to tumor cell death, that would predict response.

PATIENTS AND METHODS

Nineteen patients with advanced melanoma scheduled to receive pembrolizumab were prospectively enrolled. FDG PET/CT imaging was performed at baseline and approximately 1 week after starting treatment. FDG PET/CT scans were evaluated for changes in maximum standardized uptake value (SUVmax) and thresholds were identified by ROC analysis; MF was defined as >70% increase in tumor SUVmax, and MR as >30% decrease in tumor SUVmax.

RESULTS

An MF or MR was identified in 6 of 11 (55%) responders and 0 of 8 (0%) nonresponders, with an objective response rate (ORR) of 100% in the MF-MR group and an ORR of 38% in the stable metabolism (SM) group. An MF or MR was associated with T-cell reinvigoration in the peripheral blood and immune infiltration in the tumor. Overall survival at 3 years was 83% in the MF-MR group and 62% in the SM group. Median progression-free survival (PFS) was >38 months (median not reached) in the MF-MR group and 2.8 months (95% confidence interval, 0.3-5.2) in the SM group (P = 0.017).

CONCLUSIONS

Early FDG PET/CT can identify metabolic changes in melanoma metastases that are potentially predictive of response to pembrolizumab and significantly correlated with PFS.

Dermatomyositis in Association With SARS-CoV-2 Infection or COVID-19 Vaccine

OBJECTIVE

New-onset and relapsed dermatomyositis (DM) has been reported following SARS-CoV-2 infection or COVID-19 vaccination. This study aims to show the characteristics of a DM cohort after COVID-19 infection and vaccination.

METHODS

A retrospective review was performed on patients treated for DM between March 1, 2020, and October 31, 2022. Charts were evaluated for the presence of new-onset DM or relapse of preexisting DM following either SARS-CoV-2 infection or COVID-19 vaccination. Data on symptom onset, timing of vaccination, type of vaccination, and disease characteristics were collected.

RESULTS

Ninety-eight patients treated for DM at our institution in the Division of Rheumatology were included. In total, 12 of 98 patients (12.2%) experienced DM symptoms (either incident or relapse) following either infection or vaccination. Of the 12 patients who developed incident disease or relapse, 7 (58.3%) developed postinfection symptoms, and 8 (66.7%) developed symptoms after vaccination (3 patients had symptoms following both infection and vaccination). The mean onset of symptoms following COVID-19 infection was 3.2 days (median 0.5 days), and mean onset following COVID-19 vaccination was 5.75 days (median 3.5 days). Nine of 12 patients (75%) had a positive myositis-specific antibody, and the remaining 3 (25%) had myositis-associated antibodies. There was no predominant vaccine associated with the development of postvaccination DM symptoms.

CONCLUSION

This retrospective review revealed a strong temporal relationship between DM symptoms and COVID-19 infection or vaccination in 12.2% of all patients with DM evaluated in our clinic during the pandemic. Additional studies are required to understand the possible pathophysiology behind this association.

Comparison of post-COVID-19 vaccination hypermetabolic lymphadenopathy on 18F-fluorodeoxyglucose PET/CT between virus-vector vaccine and mRNA vaccine

PURPOSE

We compared hypermetabolic lymphadenopathy (HLN) on 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) after virus-vector and mRNA vaccines for coronavirus disease 2019 (COVID-19).

METHODS

This retrospective study included 573 participants who underwent FDG PET/CT after receiving a virus-vector vaccine (ChAdOx1, AstraZeneca [AZ] group) or an mRNA vaccine (mRNA-1273, Moderna [M] group) from July 2021 to October 2021. The incidence and avidity of HLN were evaluated and correlated with clinical features and vaccine type. The final analysis was conducted with 263 participants in the AZ group and 310 participants in the M group.

RESULTS

The HLN incidence was significantly lower in the AZ group than in the M group (38/263 [14%] vs. 74/310 [24%], p = 0.006). The FDG avidity of HLN was comparable between the two groups. The HLN incidence in both groups was significantly higher within 4 weeks after the vaccination compared with more than 4 weeks. The HLN incidence within 4 weeks of the vaccination was significantly higher in the M group than in the AZ group (p = 0.008), whereas a difference in HLN incidence between the two groups was not observed after the same duration (p = 0.11).

CONCLUSIONS

The mRNA mRNA-1273 COVID-19 vaccine was found to be associated with higher glucose hypermetabolism in regional lymph nodes within the first 4 weeks compared with the virus-vector vaccine, as indicated by the presence of HLN on FDG PET/CT. The degree of glucose hypermetabolism was comparable between the two vaccines.

COVID-19 vaccine related hypermetabolic lymph nodes on PET/CT: Implications of inflammatory findings in cancer imaging

We observed several patients presenting 2-[¹⁸F]FDG uptake in the reactive axillary lymph node at PET/CT imaging, ipsilateral to the site of the COVID-19 vaccine injection. Analog finding was documented at [¹⁸F]Choline PET/CT. The aim of our study was to describe this source of false positive cases. All patients examined by PET/CT were included in the study. Data concerning patient anamnesis, laterality, and time interval from recent COVID-19 vaccination were recorded. SUVmax was measured in all lymph nodes expressing tracer uptake after vaccination. Among 712 PET/CT scans with 2-[¹⁸F]FDG, 104 were submitted to vaccination; 89/104 patients (85%) presented axillary and/or deltoid tracer uptake, related to recent COVID-19 vaccine administration (median from injection: 11 days). The mean SUVmax of these findings was 2.1 (range 1.6-3.3). Among 89 patients with false positive axillary uptake, 36 subjects had received chemotherapy due to lymph node metastases from somatic cancer or lymphomas, prior to the scan: 6/36 patients with lymph node metastases showed no response to therapy or progression disease. The mean SUVmax value of lymph nodal localizations of somatic cancers/lymphomas after chemotherapy was 7.8. Only 1/31 prostate cancer patients examined by [¹⁸F]Choline PET/CT showed post-vaccine axillary lymph node uptake. These findings were not recorded at PET/CT scans with [¹⁸F]-6-FDOPA, [⁶⁸Ga]Ga-DOTATOC, and [¹⁸F]-fluoride. Following COVID-19 mass vaccination, a significant percentage of patients examined by 2-[¹⁸F]FDG PET/CT presents axillary, reactive lymph node uptake. Anamnesis, low-dose CT, and ultrasonography facilitated correct diagnosis. Semi-quantitative assessment supported the visual analysis of PET/CT data; SUVmax values of metastatic lymph nodes were considerably higher than post-vaccine lymph nodes. [¹⁸F]Choline uptake in reactive lymph node after vaccination was confirmed. After the COVID-19 pandemic, nuclear physicians need to take these potential false positive cases into account in daily clinical practice.

The Clinical Utility of Molecular Imaging in COVID-19: An Update

The novel pathogen severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first discovered in Wuhan, China in late 2019 with Coronavirus disease 2019 (COVID-19) declared a global pandemic in March 2020. Primarily involving the lungs, conventional imaging with chest radiography and CT can play a complementary role to RT-PCR in the initial diagnosis, and also in follow up of select patients. As a broader understanding of the multi-systemic nature of COVID-19 has evolved, a potential role for molecular imaging has developed, that may detect functional changes in advance of standard cross-sectional imaging. In this review, we highlight the evolving role of molecular imaging such as fluorine-18 (¹⁸F) fluorodeoxyglucose (FDG) with PET/CT and PET/MRI in the evaluation of both pulmonary and extra-pulmonary COVID-19, ventilation and perfusion scan with SPECT/CT for thromboembolic disease, long term follow-up of COVID-19 infection, and COVID-19 vaccine-related complications.

Hypermetabolic Ipsilateral Supraclavicular and Axillary Lymphadenopathy: Optimal Time Point for Performing an 18F-FDG PET/CT after COVID-19 Vaccination

Background: We aimed to evaluate the incidence of severe acute respiratory syndrome coronavirus type-2 (SARS-CoV2) vaccine-related hypermetabolic lymphadenopathy (HLA) and evaluate which time point produces the least number of false-positive findings in an 18F-2-Fluor-2-desoxy-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT). Methods: For this retrospective, multi-center imaging study, patients with any form of SARS-CoV2 vaccination prior to an 18F-FDG-PET/CT were included between January 2021 and December 2021. Patients were divided into six groups according to the time point of vaccination prior to their 18F-FDG-PET/CT imaging, e.g., group one (0−6 days) and group six (35−80 days). As the reference standards, the SUVmax of the mediastinal blood pool (MBP) and the SUVmax contralateral reference lymph node (RL) were determined. (A) The absolute SUVmax of HLA, (B) the ratio of SUVmaxHLA/SUVmax mediastinal blood pool (rHLA/MBP), (C) the ratio SUVmax HLA vs. SUVmax contralateral reference lymph node (rHLA/RL), (D) and the incidence of HLA defined as rHLA/MBP > 1.5 were assessed. Results: Group one (days 0−6) showed the highest incidence of HLA 16/23 (70%) and rHLA/MBP (2.58 ± 2.1). All three parameters for HLA reduced statistically significantly in the comparison of Groups 1−3 (days 0−20) versus Groups 4−6 (days 21−80) (p-values < 0.001). Conclusions: If feasible, an FDG PET should be postponed by at least 3 weeks after SARS-CoV2 vaccination, especially if an accurate evaluation of axillary status is required.

Evaluation of metabolic changes in FDG PET/CT imaging after mRNA-based COVID-19 vaccination

BACKGROUND

It isimportant to evaluate the vaccine-related metabolic changes on FDG PET/CT to avoid confusing results. We here aimed to assess the frequency and intensity of regional and systemic metabolic PET/CT changes of patients who received the mRNAbased COVID-19 vaccine (BNT162b2-Pfizer/BioNTech) and to analyze possible factors affecting these changes.

METHODS

Among the patients who underwent FDG PET/CT for any indication in our department between July 2021 and December 2021, 129 volunteer patients with a history of COVID-19 vaccination were included in this prospective observational study. Bilateral axillary lymph nodes, ipsilateral deltoid muscle, bone marrow, spleen, thyroid, and liver FDG uptakes were evaluated visually and semiquantitatively for each examination.

RESULTS

The frequencies of positive axillary lymph nodes after vaccination were 40%, 44.4%, 32.6%, and 44.7% in all, 1st dose, 2nd dose, and heterologous vaccination regimens groups, respectively. Maximum standardized uptake values of spleen, liver, and bone marrow were statistically high in patients with positive axillary lymph nodes than with negative ones (p < 0.05). Positive deltoid muscle uptake and diffusely increased thyroid uptake findings were observed in 10 and 8 patients, respectively. The median time interval between vaccination and imaging was 9.5 days for patients with positive axillary lymph nodes and 17 days for patients with negative nodes. In our study group, only 8 patients had a positive documented history of COVID-19 infection.

DISCUSSION

Regional and systemic metabolic changes were occasionally found on FDG PET/CT imaging in patients who received the mRNA-based COVID-19 vaccine. To avoid these timely decreasing changes, we recommend managing the ideal timing of imaging or vaccination and taking a careful history.

Oncology and cardiology positron emission tomography/computed tomography faced with COVID-19: A review of available literature data

The COVID-19 pandemic has forced people to significantly change their lifestyles and attitudes, and has greatly burdened healthcare delivery systems worldwide. The redistribution of the medical delivery system to maintain normal medical care while responding generously to COVID-19 is a continuing challenge that weighs heavily on medical institutions. Among imaging modalities, chest X-rays and computed tomography (CT) examinations have clearly made a large contribution to treatment of COVID-19. In contrast, it is difficult to express the standpoint of nuclear medicine examinations in a straightforward manner, as the greatest emphasis in this modality has been on how necessary medical care can continue to be provided. Many clinical reports of nuclear medicine examinations related to COVID-19 have been published, and knowledge continues to accumulate. This review provides a summary of the current state of oncology and cardiology positron emission tomography (PET) examinations related to COVID-19, and includes preparation of the nuclear medicine department, trends in PET examinations, specific imaging findings on 18F-fluorodeoxyglucose (FDG) PET/CT, imaging of complications of COVID-19, PET tracers other than FDG, and the effects of vaccines on PET imaging findings.

What Should We Do after the COVID-19 Vaccination? Vaccine-Associated Diseases and Precautionary Measures against Adverse Reactions

COVID-19 vaccines have been used to counteract the global COVID-19 pandemic. While these are effective, adverse reactions have been reported, such as injection-site pain, muscle ache, fever, palpitation, and chest discomfort. The release of inflammatory cytokines, such as interleukin (IL)-6 and IL-1β, is a potential mechanism for post-vaccine side-effects. Chest discomfort after the vaccination, including myocarditis and acute coronary syndrome, is a particularly serious adverse reaction. It is important to be familiar with the differential diagnoses of chest discomfort and organ-specific diseases associated with COVID-19 vaccines as the preparation for booster shots and vaccinations among children aged 5–11 years begins. High-intensity exercise, alcohol, tobacco smoking, and baths promote inflammatory cytokines, such as IL-6, which may exacerbate the adverse reactions after vaccination. Japanese data show that deaths during baths are the most common for several days after mRNA vaccination. Additionally, alcohol and tobacco smoking were identified as predictive factors of lower antibody titers after vaccination. In this review, we aimed to provide a few recommendations to prevent vaccine-associated disease.