COVORTS (f)MRI sub-study
Sniffing out Covid: COVORTS study (COVid cohORT on Smell loss), long COVORTS and Imaging smell loss in Covid-19, an (f)MRI approach
Structural and odour-task functional brain MRI of adults with persistent smell loss or parosmia after COVID-19, collected to study olfactory bulb volume, grey matter and odour-evoked brain activity. Scans are not shared; the data record holds questionnaire and smell-test data.
Overview
The Sniffing out Covid project at Wageningen University & Research, funded by ZonMw, followed people whose sense of smell stayed impaired after a SARS-CoV-2 infection. It has three research lines: the COVORTS cohort, followed for a year with questionnaires and home smell and taste tests; long COVORTS, a questionnaire cohort of people with smell problems lasting six months or more; and an (f)MRI sub-study. This entry covers the (f)MRI sub-study. Its scans are not released. The shared DANS record holds tabular data from the COVORTS cohort under a data transfer agreement, and states that derived imaging values will follow once the project ends.
Composition
The (f)MRI preprint analysed 48 patients aged 19 to 60 (38 women, 10 men, mean age 47.4). 21 had quantitative smell loss by Sniffin' Sticks score (8 anosmic, 13 hyposmic) and 27 reported parosmia. 29 came from the longitudinal COVORTS cohort and 19 joined only for imaging. Infection had been confirmed by PCR or antigen self-test, on average 472 days before inclusion. Patients were scanned between January 2022 and June 2024. The preprint compares them with 49 normosmic controls from a separate Wageningen study, which this record does not include. The data record had planned 50 patients in two groups of 25.
Acquisition
All scans were made on a 3 T Philips Elition X with a 32-channel head coil. Each session had a coronal T2-weighted scan of the olfactory bulbs, a 3D T1-weighted TFE whole-brain scan at 0.8 mm, and multiband gradient-echo EPI fMRI at 2.2 mm during an odour task with chocolate and beef odours, blanks and matching food pictures. The data record planned a follow-up scan for patients first scanned within six months of infection; the preprint does not describe follow-up scans.
Annotations
Two trained raters manually segmented the olfactory bulbs in ITK-SNAP and reconciled differences above 10%. In 2 patients no bulbs were visible. Grey matter was segmented with CAT12 in SPM12.
Known limitations
- The images are not shared; only derived volumes and scores are announced for release.
- Smell tests and the parosmia questionnaire were not done on the scan day.
- The patient group is mostly female and older than the controls in the preprint.
- Results come from a preprint that was not yet peer reviewed when this entry was written.
Cohort
Aggregate numbers from the sources below. Bars are relative to the 48 subjects.
Sex
- Female 38 79%
- Male 10 21%
Table 1 in van Dijk et al. 2026, medRxiv preprint (COVORTS (f)MRI study)
Condition
Groups can overlap
- COVID-19 48 100%
- Olfactory dysfunction 48 100%
- Parosmia 27 56%
Table 1 in van Dijk et al. 2026, medRxiv preprint (COVORTS (f)MRI study)
Field strength
- 3 T 48 100%
Section 2.2.4 in van Dijk et al. 2026, medRxiv preprint (COVORTS (f)MRI study)
Age
mean 47.4 ± 9.5, range 19 to 60
No age bins reported.
Table 1 in van Dijk et al. 2026, medRxiv preprint (COVORTS (f)MRI study)
Contrast / sequence
Groups can overlap
- T1-weighted 48 100%
- T2-weighted 48 100%
- BOLD fMRI 48 100%
Table 1, Section 2.3.1, Section 2.3.3.1 in van Dijk et al. 2026, medRxiv preprint (COVORTS (f)MRI study)
Scanner vendor
- Philips 48 100%
Section 2.2.4 in van Dijk et al. 2026, medRxiv preprint (COVORTS (f)MRI study)
Country
- Netherlands 48 100%
Metadata: spatial coverage in DANS Data Station Life Sciences record doi:10.17026/LS/YZHHK7
License and access
Our reading of the license, not legal advice. Before you use the data, read the original license and confirm that your use is allowed. We take no responsibility for how you use a dataset. Full disclaimer
The data are not available outside the institution or study that holds them
No published license or data use terms
The data holder has published no license and no data use terms. Any use, sharing or commercial right has to be agreed with the data holder, and nothing can be assumed to be allowed. Default copyright and data protection law still apply.
The DANS record states that only derived values (olfactory bulb, intracranial, grey and white matter volumes, demographics and smell-test scores) of the imaging line will be published after project completion; the scans themselves are not listed for release. The record's DANS Licence and data transfer agreement cover the questionnaire and smell-test files of the longitudinal cohort, which are available on request for research on chemosensory dysfunction only.
What you can do
- Commercial use Not stated
- Not stated
- Train ML models Not stated
- Create derived data Not stated
- Publish results Not stated
What you can share
- Share the data Not stated
- Share derived data Not stated
- Share trained models Not stated
What you must do
- Cite or credit Not stated
- Share alike Not stated
- Sign an agreement Not stated
- Ethics approval Not stated
- Manuscript review Not stated
- Release code Not stated
- Return results Not stated
- Delete after use Not stated
Limits
- No re-identification Not stated
- Location limits Not stated
Citation
Boesveldt S, van Dijk B. Sniffing out Covid - 'COVORTS study: the COVid cohORT on Smell loss', 'long COVORTS: the COVid cohORT on long-term Smell Loss' and 'Imaging smell loss in Covid-19: an (f)MRI approach'. DANS Data Station Life Sciences, version 1.1 (2026). doi:10.17026/LS/YZHHK7
Sources
Every number on this page comes from one of these documents. Each chart names the table or page it is taken from. The raw numbers are in stats.csv.