During the current nascent pandemic, anosmia has been increasingly reported among patients with coronavirus disease-2019 (COVID-19) (1). While postviral olfactory loss secondary to nasal congestion or conductive pathway alteration is a known sequela of sinonasal viral infections (2), anosmia of COVID-19 is less commonly associated with rhinorrhea or nasal congestion (3). This may indicate sensory neural loss as the underlying cause of the olfactory dysfunction rather than the conductive mechanism in most cases of postviral olfactory loss. We have recently reported normal morphology of the olfactory bulb on magnetic resonance imaging in anosmia of COVID-19 (4). Whether there is decreased neural activity in olfactory pathways despite normal morphology is unknown. We sought to assess the neural metabolic activity in anosmia of COVID-19 by 18fluoro-2-deoxy-d-glucose (18FDG) positron emission tomographyÀcomputed tomography (PET-CT). We included a 27-year-old healthy, right-handed woman, diagnosed with COVID-19 by polymerase chain reaction assay. The patient had persistent isolated anosmia for 6 weeks. She had no history of alcohol intake or tobacco smoking and no background of psychiatric problems. The patient was asked to fast for 6 hours prior to imaging. We performed 18FDG-PET/CT in a neutral environment using 5 ml of aerosolized 0.9% NaCl delivered with O 2 at 3.5 ml/min via facial mask for 9 minutes. The patient was instructed to breath normally without sniffing. After 3 minutes, the patient received intravenous 18FDG (4.6 Megabecquerel/kg, Masih Daneshvari Hospital, Tehran), and the neutral olfactory condition continued for another 6 minutes. The patient laid down in a semi-darkened,
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