Keywords
Netspot - coronavirus - PET
Key Messages
COVID-19 should be included in the differential diagnosis when radiotracer uptake
appears in NETSPOT 68Ga-DOTATATE PET/CT. Current documented false-positive findings for 68Ga-DOTATATE PET/CT include pancreatic uncinate process activity, prostatitis, splenosis,
postradiation therapy change, paraganglioma, pheochromocytoma, neuroblastoma, meningioma,
and osteoblastic activity.
Introduction
The coronavirus disease 2019 (COVID-19) outbreak has infected over 131 million people
and caused 2.85 million deaths worldwide, as of early April 2021.[1] In many patients, COVID-19 presents with nonspecific symptoms such as fever, cough,
and chest pain, while in some others, the infection remains asymptomatic.[2] Despite its suboptimal sensitivity, nucleic acid testing (reverse transcription
polymerase chain reaction [RT-PCR]) has been regarded as the gold standard to confirm
the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Imaging
can be a useful adjunct. In symptomatic patients, chest X-rays are typically obtained.
Computed tomography (CT) chest may be added as a key supplemental tool for the diagnosis
of SARS-CoV-2 given its reported improved sensitivity relative to RT-PCR (98 vs. 71%).[3] Recently, several groups have reported the incidental [18F]-2-fluoro-2-deoxy-D-glucose
(FDG)—positron emission tomography/computed tomography (PET/CT) imaging findings of
COVID-19 (18F-FDG PET) in the diagnosis of COVID-19.[4]
[5]
[6] The most prominent features reported on FDG-PET/CT in patients with COVID-19 include
FDG uptake in pulmonary parenchymal lesions that are typically peripheral, bilateral,
ground glass opacities.[5]
In the detection and characterization of neuroendocrine tumors (NETs), the NETSPOT
68Ga-DOTATATE PET/CT utilizes a somatostatin analog to capture whole body imaging
of somatostatin receptors. Somatostatin receptor imaging is successfully accomplished
using 111In-DTPA-penteoctreotide (Octreoscan).[7] However, downsides to Octreoscan (including suboptimal spatial resolution, suboptimal
image quality, and multiple day imaging protocols) have led to the development of
several chelator-conjugated somatostatin analogs, including DOTATATE. These short
amino acid–chelator conjugates have a higher affinity than Octreoscan for somatostatin
receptors. Further, they can be labeled with 68Ga, permitting imaging with PET and improved spatial resolution and image quality.[7] Here, to our knowledge, we report the first case of incidental COVID-19 detection
using 68Ga-DOTATATE PET/CT for a patient with COVID-19 who presented to our nuclear medicine
department for oncologic and neuroendocrine indications.
Discussion
The increase in reported incidental findings of COVID-19 on FDG-PET/CT imaging underscores
the impact nuclear medicine may have outside of the oncologic setting. FDG-PET/CT
plays a role in evaluating various inflammatory and infectious diseases, which may
guide patient management and treatment.[8] Before the appearance of COVID-19, Das et al reported significant FDG uptake in
a patient with Middle East respiratory syndrome coronavirus infection that ultimately
progressed to pneumonia.[9]
In our case, an asymptomatic COVID-19 patient presented to our clinic for neuroendocrine
cancer screening, and we observed pathologic uptake within the pneumonia using 68Ga-DOTATATE PET/CT. It is important that the clinician be aware of potential false
positives when imaging with this radiotracer.
Current documented false-positive findings for 68Ga-DOTATATE PET/CT include pancreatic uncinate process activity, prostatitis, splenosis,
postradiation therapy change, paraganglioma, pheochromocytoma, neuroblastoma, meningioma,
and osteoblastic activity.[10] This case adds COVID-19 pneumonia to the list. With the growing number of worldwide
COVID-19 cases, and the continued use of NETSPOT for somatostatin avid neoplasms,
it is imperative that diagnostic measures of this disease are clearly understood.
This case highlights the importance of including COVID-19 on the differential diagnosis
when radiotracer uptake appears in 68Ga-DOTATATE PET/CT.
Authors' Contributions
JPW was involved in conceptualization, designing, definition of intellectual content,
literature search, manuscript preparation, review, and editing. TB contributed substantially
in conceptualization, designing, definition of intellectual content, manuscript review
and editing. TB has provided guarantee for this manuscript.
