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Consecutive patients who underwent simultaneous head and neck ¹⁸F-FDG-PET/MR imaging staging or restaging followed by surgery were retrospectively included in this study. Local tumor invasion and lymph node extension were assessed by 2 rater groups in 45 head and neck anatomic regions using ¹⁸F-FDG-PET/MR imaging. Two reading sessions were performed, one without contrast-enhanced sequences (using only T1WI, T2WI, and PET images) and a second with additional T1-weighted postcontrast sequences. The k concordance coefficient between the reading sessions and sensitivity and specificity for each region were calculated. There was excellent agreement between the contrast-free and postgadolinium reading sessions in delineating precise tumor extension in the 45 anatomic regions studied. The diagnostic accuracy did not differ between contrast-free and postgadolinium reading sessions, being 0.97 for both groups and both reading sessions. The authors conclude that gadolinium-based contrast administration showed no added value for accurate characterization of head and neck primary tumor extension and could possibly be avoided in the PET/MR imaging head and neck workflow.

The authors present 5 cases that illustrate varying imaging presentations of acute encephalopathy in patients with coronavirus disease 2019. MR features include leukoencephalopathy, diffusion restriction that involves the GM and WM, microhemorrhages, and leptomeningitis.