Shiga H, Okuda K, Taki J, et al. - In this retrospective analysis, researchers ascertained if nasal thallium-201 uptake of the olfactory cleft and olfactory bulb (OB) varies between patients with parosmia, a distortion of smell sensation, with and without hyposmia after upper respiratory tract infection (URTI). The study sample consisted of 20 patients (aged 28 to 76 years) with parosmia after URTI. Those patients were excluded if they were pregnant or lactating or if they had a history of kidney disease, liver injury or other serious diseases. In the olfactory cleft, the nasal thallium-201 uptake ratio in the parosmia group was significantly higher than in the parosmia and hyposmia group. The results indicate the olfactory epithelium recovery. However, in patients with parosmia with normal T&T recognition thresholds after URTI, olfactory neural projections to OB and OB regeneration were not complete.