key: cord-0993160-373pist8
authors: Martinez, Ricardo Bello; Ghesani, Munir; Ghesani, Nasrin; Gavane, Somali
title: Asymptomatic SARS-CoV-2 infection- Incidental findings on FDG PET/CT
date: 2021-03-16
journal: J Med Imaging Radiat Sci
DOI: 10.1016/j.jmir.2021.03.002
sha: fb679e580767e02432c013b964b1c240b000ca5d
doc_id: 993160
cord_uid: 373pist8

RATIONALE AND OBJECTIVES: Identify the incidental findings of Covid-19 pneumonitis on (18)F-FDG PET/CT scan in asymptomatic oncologic patients. The goal was to detect clinically unsuspected Covid-19 infections to prevent community spread. MATERIALS AND METHODS: Retrospective analysis was conducted to recognize the pattern of metabolic and radiographic alterations on (18)F-FDG PET/CT scans in Covid-19 patients. 492 (18)F-FDG PET/CT scans were reviewed for pulmonary and systemic abnormalities. RESULTS: (18)F-FDG PET/CT demonstrated new lung infiltrates in 29 asymptomatic patients. 13/29 patients had Covid-19 infection confirmed by nasopharyngeal nucleic acid PCR test. The most common lung abnormality was pure ground-glass opacity (GGO) (90%) in peripheral distribution (100%), involving 1 lobe in four patients (30.8%), 2-3 lobes in four patients, and 4-5 lobes in five patients (38.4%). Mean SUVmax was 4.7 (range 1.3-13.1). Ten patients developed symptoms, mainly fever, fatigue, and dry cough, within 6.4 ± 7.8 days (range 1-24). Of the available laboratory data of 12 patients, eight developed lymphopenia, and five patients had neutrophilia. Five patients required hospitalization, and two died of complications. CONCLUSION: For a given geographic region in the later stage of a pandemic, such as Covid-19, community spread of the disease is common. Therefore, it is not surprising to find it in asymptomatic being imaged for other indications. Recognition of its manifestation and effectively mounting mitigation protocols is essential to further reduce SARS-CoV-2 spread, especially to susceptible groups, predominantly the elderly and people with comorbidities.

The Covid-19 pandemic has drastically compromised many daily routines worldwide since December 2019. Over 49 million confirmed cases and more than 1,240,000 deaths have been reported worldwide. 1 The novel coronavirus SARS-CoV-2 was initially associated with a seafood market in China where live animals were sold. 2 Its transmission is primarily person to person, occurring in close contact mainly via respiratory droplets. 3 The virus uses the angiotensin-converting enzyme 2 (ACE2) as a cell receptor for cellular entry, mainly present in the human respiratory epithelium from where it can disseminate to other organs; 4 it can result in lung injury, and severe cases progress to severe respiratory distress syndrome or multi-organ failure. 5 Early-stage Covid-19 infection can be seen in chest CT as lung parenchymal groundglass opacification (GGO) or consolidation that is likely to be bilateral and peripheral in distribution. 6 Asymptomatic or presymptomatic carriers contribute to the viral spread, and recognition of imaging findings suggestive of Covid-19 pneumonia plays a crucial role in detection and mitigation strategies, mainly when imaging is performed for SARS-CoV-2 unrelated reasons. 7 Elderly oncologic patients, who are susceptible to severe Covid-19 due to immunosuppression caused by anticancer treatment and malignancy, often have the absence of symptoms or are atypical, attributed to underlying conditions. 8 Imaging metabolic pathways with PET/CT 18 F FDG in oncologic applications aid accurate diagnosis, assessing disease status, and response to treatment on serial imaging. 9 Not infrequently, whole-body PET scans detect incidental like Covid-19 pneumonia characterized with a high degree of uptake. 10 18 F FDG PET/CT plays a role in evaluating infectious and inflammatory diseases, monitoring disease progression and assessing treatment response, improving patient outcomes. 11 The discovery of new lung infiltrates on routine PET/CT suggestive of infection should raise suspicion, given the pandemic situation. 12 Despite public health plans to control the spread, the United States has more cases than any other country accounting for over 9 million confirmed cases. 1 As an international hub and its dense population, New York City became the pandemic's epicenter in early 2020. 13 We present Covid-19 infection FDG PET/CT findings in asymptomatic oncologic patients during the disease outbreak.

Retrospective analysis of PET/CT scan performed between March 10, 2020, and April Administration (FDA). The diagnostic test's clinical sensitivity and specificity also vary by the specimen source, quality of sampling technique, disease course timing, and illness severity. Additionally, no robust data assessing the nasopharyngeal test sensitivity on asymptomatic infected individuals exist. Given our cohort's high pretest probability for having been located in a prevalent area, one needs a highly sensitive test to reliably deemed true-negatives; hence we might have underestimated our positive cases. 15 Nonetheless, testing allows tracking the viral spread and isolation of infected cases, estimates local prevalence, necessary in the risk-benefit assessment of safety of performing routine nonurgent radiologic care or postponing any examination given the risk of healthcare-acquired Covid-19, considering patients' demographics and comorbidities. 16 RT-PCR is also used to triage before debilitating interventions like surgery or chemoradiation that can be complicated by a severe infectious process.

Many asymptomatic carriers lack radiographic abnormalities or have a false negative RT-PCR that undermines prevention measurements based on the presence of symptoms, imaging findings, or laboratory results. 17 It is essential to adapt universal prevention strategies as masking, physical distancing, and hand hygiene to prevent asymptomatic spread and exposure to vulnerable patients. Five of the presented cases were subsequently hospitalized, and two died, reflecting the vulnerability of elderly oncologic patients. In health care centers where exposure risks are higher, comprehensive measures as Covid-19 safety algorithms, readily available personal protective equipment, and protocols for staff and patients are the cornerstone for safe operations. Telehealth, as the remote delivery of care and tools for employees attesting their health status before each shift, should also be implemented when feasible. 18, 19 The oncologic population commonly presents with benign infectious/inflammatory lung processes, often treatment-related, that nor radiographic or scintigraphy findings can differentiate from other viral or non-viral atypical types of pneumonia. 20 Imaging should be used as an adjunct to patient management. 21 FDG PET/CT is useful in assessing infectious and inflammatory cardiopulmonary processes. It allows quantification of radioactivity, providing a biomarker of the inflammatory process in vivo. 22 It is also sensitive for detecting lymph node involvement and assesses response to treatments; however, PET/CT scan currently does not have a role in the management of Covid-19.

The long-time interval between PET/CT scan RT-PCR in our population can be explained by testing-supply shortage at that time and isolated patients after PET/CT that sought medical care later.

Incidental findings seen on nonurgent radiologic care suggestive of Covid-19 pneumonia in asymptomatic patients should be interpreted along with clinical, laboratory, and epidemiologic information for an accurate diagnosis and preventive measures. Protocols to deliver care, minimizing the risk of exposure are of utmost importance to protect susceptible patients from Covid-19 infection and hospital staff. 

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