Keywords
68 Ga-DOTATATE - COVID-19 - NETSPOT - positron-emission tomography - vaccination
Introduction
As of April 18, 2021, 206 million doses of COVID-19 vaccinations have been given in
the United States.[[1 ]] As vaccination rates continue to rise, it is becoming increasingly important to
understand incidental imaging findings resultant from these new messenger ribonucleic
acid (mRNA) vaccines. Recently, there have been several groups that have reported
fludeoxyglucose (FDG) uptake on positron-emission tomography/computed tomography (PET/CT)
regarding COVID-19-related findings.[[2 ]],[[3 ]],[[4 ]] The most commonly reported features visualized on FDG-PET/CT in patients with COVID-19
include FDG uptake in pulmonary parenchymal lesions that are typically peripheral,
bilateral, and ground-glass opacities.[[3 ]] In addition to this, COVID-19 disease having an association with radiopharmaceutical
uptake in FDG-PET/CT, mRNA vaccinations have also been implicated with benign axillary
node uptake.[[5 ]] False-positive associations can lead to unwarranted additional testing and biopsies
of benign etiologies. With the growing uncertainty of COVID-19, it is critical that
we understand and report diagnostic false positives on a variety of imaging modalities
to ensure best practices.
One diagnostic agent used in the detection and characterization of neuroendocrine
tumors is gaining substantial ground in clinical practice. Specifically, NETSPOT PET/CT
utilizes a somatostatin analog to capture whole-body imaging of somatostatin receptor
expression. The speed of 68Ga-DOTATATE PET/CT relative to FDG-PET/CT allows for the
detection of smaller somatostatin-avid tumors such as neuroendocrine neoplasms.[[6 ]] Here, we report a rare false-positive case of right axillary radiopharmaceutical
nodal uptake visualized with 68Ga-DOTATATE PET/CT for a patient who presented to our
nuclear medicine department for neuroendocrine indications. A medical history revealed
that the patient received both doses of an ipsilateral COVID-19 mRNA vaccine injection
at 17 and 38 days before the PET/CT evaluation.
Case Report
In January of 2021, a 59-year-old female with a known history of gastrointestinal
neuroendocrine carcinoma presented to our clinic for the status of disease and was
evaluated with 68Ga-DOTATATE PET/CT. The PET scan displayed focal uptake of the somatostatin
analog in the right axilla [[Figure 1 ]]. The intensity of uptake was moderate and corresponded to several normal-sized
lymph nodes with no enlargement [[Figure 2 ]] on CT. Upon questioning, it was discovered that the patient had received both doses
of a COVID-19 mRNA vaccination at 17 days and 38 days prior to this PET/CT. The ipsilateral
COVID vaccine injection at 17 days and 38 days prior to imaging was given in the right
deltoid. These findings were not present on a previous scan 4 months earlier (not
shown). Subsequent scan 2 months later for standard treatment follow-up demonstrated
resolution of infiltrates and associated radiopharmaceutical uptake (not shown).
Figure 1 Axial (top) and Coronal (bottom) 68 Ga-DOTATATE positron-emission tomography/computed tomography images demonstrate focal
uptake in the right axilla. Intensity of uptake is moderate
Figure 2 Axial (top) and coronal (bottom) 68 Ga-DOTATATE positron-emission tomography/computed tomography fusion images demonstrate
that the uptake corresponds to several normal-sized and benign-appearing lymph nodes.
Seventeen days before the scan, the patient had received an ipsilateral COVID vaccine
injection on this side
Discussion
The COVID-19 pandemic has caused significant mortality throughout the world as well
as social and economic disturbances. In the field of nuclear medicine, we describe
some impactful imaging findings associated with the COVID-19 mRNA vaccinations.
The increase in reported incidental findings of COVID-19 on FDG-PET/CT imaging highlights
the role nuclear medicine may have outside of the oncologic setting. FDG-PET/CT plays
a role in evaluating various infectious, inflammatory, and other hypermetabolic diseases
which may guide patient management and treatment. A few case reports and series have
identified radiopharmaceutical uptake on FDG-PET/CT due to both COVID-19 disease and
vaccination.[[7 ]],[[8 ]] However, the association between NETSPOT PET/CT and COVID-19 vaccinations has not
been previously reported.
In our case, a patient in remission for neuroendocrine cancer presented to our clinic
for routine screening, and we observed benign uptake using 68Ga-DOTATATE PET/CT. The
patient had previously received a right ipsilateral COVID-19 injection 17 and 38 days
prior to imaging. This was consistent with the observed findings. It is important
that the clinician be aware of potential false positives when imaging with this radiopharmaceutical.
We anticipate the utility of NETSPOT will gain a wider clinical approval within the
coming years, and with the uncertainty of COVID-19, we must understand potential false-positive
associations with this imaging modality. Documenting any vaccination prior to imaging
may help to avoid false interpretation of the PET/CT scan. Current documented false-positive
findings for 68Ga-DOTATATE PET/CT include prostatitis, splenosis, pancreatic uncinate
process activity, paraganglioma, meningioma, and osteoblastic activity among others.[[7 ]] This case adds COVID-19 vaccination to the list. With the growing number of worldwide
COVID-19 cases, and the continued use of NETSPOT for somatostatin receptor-avid neoplasms,
it is imperative that diagnostic measures of this disease are clearly understood.
This case highlights the importance of including COVID-19 vaccinations as a potential
false positive when radiopharmaceutical uptake appears on NETSPOT PET/CT.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form the patient(s) has/have given his/her/their consent for his/her/their
images and other clinical information to be reported in the journal. The patients
understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
