SNMMI warns of omicron's impact on PET/CT scans

By Will Morton, staff writer

January 14, 2022 -- The COVID-19 omicron variant appears to cause an unusual imaging pattern on FDG-PET/CT scans in cancer patients, according to a statement released January 14 by the Society for Nuclear Imaging and Molecular Imaging (SNMMI) COVID-19 Task Force.

"Task Force members have recently observed an unusual imaging pattern on FDG-PET/CT or FDG-PET/MR that appears to correlate with the COVID-19 infection," SNMMI stated.

Unlike the FDG PET/CT pattern seen with infections from previous strains of COVID-19, with principal involvement of the lungs, this new array of findings is primarily centered in the upper aerodigestive tract and cervical lymph nodes, the task force reported.

Specifically, there is prominent, symmetric FDG uptake throughout the nasopharynx, oropharynx, and tonsils (Waldeyer's ring) with or without associated FDG-avid cervical lymphadenopathy, particularly in the suprahyoid neck.

FDG uptake on PET/CT in nasal-associated lymphoid tissue in a cancer patient infected with the COVID-19 omicron variant.
FDG uptake on PET/CT in nasal-associated lymphoid tissue in a cancer patient infected with the COVID-19 omicron variant. Image courtesy of Dr. Munir Ghesani.

Dr. Munir Ghesani, chief of nuclear medicine and molecular imaging at Mt. Sinai Health in New York City and chair of SNMMI's COVID-19 Task Force, said he began noticing what appeared to be a consistent pattern about a week ago and quickly confirmed similar findings on FDG-PET/CT in cancer patients with colleagues in Boston, Los Angeles, and Atlanta.

"This was very new and exciting and disturbing at the same time," he told He added that the pattern has been seen in both adults and children.

Based on the findings, the task force suggests that physicians take the pattern into consideration at the time of FDG PET/CT interpretations. However, since this new pattern "can by no means be diagnostic of COVID-19 infection," the SNMMI's COVID-19 Task Force has made the following recommendations:

  1. Check patient records for recent positive COVID-19 tests.
  2. Determine if the patient is at higher risk of COVID-19 infection based on current symptoms or due to recent exposure or travel. If so, a recommendation can be made to test for COVID-19 in the appropriate setting.
  3. Compare with prior FDG PET/CT examinations and the patient's history to determine if this represents chronic inflammatory/reactive process or stable malignancy, such as lymphoma.

In addition, various differential diagnostic possibilities should be considered if the omicron pattern is new or if there is interval progression, including but not limited to infection with COVID-19, other viruses such as Epstein-Barr virus, malignancy, and bacterial infections.

Lastly, since the pattern has also been seen in children and younger adults, it should be interpreted cautiously in light of potential normal increased physiologic activity. Correlation with history and symptoms and comparison to prior examinations is recommended, the statement concluded.

Copyright © 2022

To read this and get access to all of the exclusive content on create a free account or sign-in now.

Member Sign In:
MemberID or Email Address:  
Do you have a password?
No, I want a free membership.
Yes, I have a password:  
Forgot your password?
Sign in using your social networking account:
Sign in using your social networking