FDG PET/CT May Help Predict COVID-19 Disease Severity

The detection rate of COVID-19 infection on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) is relatively low, according to a study published this month in Clinical Imaging. However, the use of FDG PET/CT may help predict disease severity, as study patients with positive scans tended to be symptomatic and require hospitalization.

“During the peak of the pandemic in New York City, we started noticing that patients coming in for FDG PET/CT for their cancer care had lung findings suggestive of COVID-19,” said Randy Yeh, M.D., of the department of radiology at Memorial Sloan Kettering Cancer Center in New York. “We decided to perform a study to evaluate the imaging features of COVID-19 on FDG PET/CT and to determine the clinical utility of FDG PET/CT in COVID-19, if any.”

This single institution retrospective review included 31 patients (mean age 57 years, 21 males) with COVID-19, diagnosed using real time reverse transcription–polymerase chain reaction, who had undergone FDG PET/CT for routine cancer care between March 1, 2020 to April 30, 2020, the peak of the pandemic in New York City.

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Of the patients, 13 had positive PET/CT scans for COVID-19, representing a detection rate of 41.9%. Patients with positive scans had higher rates of symptomatic COVID-19 infection compared with patients who presented with negative scans, at 77% and 28%, respectively (P = .01). A similar result was seen for hospitalizations, at 46% and 0%, respectively, (P = .002). Of the patients with positive scans, 11 had FDG-avid lung findings, with mean lung SUV_max of 5.36, and six had extrapulmonary findings of FDG-avid lymph nodes. Lung SUV_max was unrelated to the presence of COVID-19 symptoms, severity or disease course. Deaths from COVID-19 did not differ between those with and with positive scans. (P = .2).

“The findings do not change the diagnostic pathway or main imaging modalities for COVID-19, which remain chest radiography and CT chest. However, our findings do raise awareness that COVID-19 can be detected on FDG PET/CT and that it portends more severe disease,” Yeh said.

Yeh noted that clinicians, especially those working in a region of high COVID-19 prevalence, should be aware that FDG PET/CT can detect lungs and lymph node findings suggestive of COVID-19. He added that “nuclear medicine physicians and radiologists interpreting FDG PET/CT scans should be aware of the typical findings of COVID-19 and alert referring clinicians if they see such findings, as this may be the first sign that a patient has COVID-19,” he added.