Stefano Raffa (Italy)
University of Genoa and IRCCS Ospedale Policlinico San Martino Department of Health Science (DISSAL)Author Of 2 Presentations
METABOLIC SIGNATURE OF HYPOSMIA AFTER MILD COVID-19: AN [18]F-FDG-PET STUDY.
- Matteo Pardini (Italy)
Abstract
Background and Aims:
Persistent hyposmia represents one of the most common neurological complications of coronavirus disease 2019 (COVID-19) due to SARS-CoV-2 infection. To date, however, its neural bases remain poorly understood.
Methods:
Sixty-two patients (mean age 64 ± 10.5 years, range 35-79) underwent whole-body [18]F-FDG-PET including a dedicated brain acquisition following their recovery after SARS-Cov2 infection. Patients that previously required mechanic ventilation or showed severe respiratory distress syndrome due to SARS-CoV-2 infection were excluded given the potential independent effect of these clinical scenarios on brain metabolism. The presence of isolated persistent hyposmia was assessed with the smell diskettes olfaction test. Voxelwise analyses were used to compare hyposmic and non-hyposmic patients and controls (61 subjects, age 61.1 ± 11.1 years), as well as to correlate regional metabolism with quantitative performance at the olfaction test.
Results:
Relative hypometabolism was demonstrated in bilateral parahippocampal and fusiform gyri and in left insula in hyposmic patients with respect to controls and in the orbitofrontal cortex in hyposmic patients compared to non-hyposmic patients. In the hyposmic group, quantitative performance at the olfaction test correlated with regional metabolism in the cingulate gyrus, in the bilateral thalami and in the right temporal gyrus.
Conclusions:
Isolated persistent hyposmia hyposmia after SARS-Cov2 infection without an history of severe respiratory distress is associated with significant metabolic alterations in regions beyond those involved in primary olfactory processing.
ACCURACY OF FDG-PET AT THE INDIVIDUAL LEVEL IN MCI-LB VERSUS MCI-AD: A STEPWISE APPROACH FROM VISUAL TO SEMI-QUANTITATIVE ANALYSIS
- Federico Massa (Italy)
Abstract
Background and Aims:
FDG-PET is an established supportive biomarker in dementia with Lewy bodies (DLB), but its diagnostic accuracy is unknown in prodromal stages (MCI-LB) when the typical metabolic pattern may be difficultly recognized at the individual level. Semiquantitative analysis of scans can enhance accuracy especially in less skilled readers, but its added role with respect to visual assessment at this DLB stage is still unknown.
Methods:
We assessed the diagnostic accuracy of visual assessment of FDG-PET by six expert readers, blind to diagnosis, in discriminating two matched groups of patients (40 with prodromal AD, MCI-AD, and 39 with MCI-LB), both confirmed by in vivo biomarkers of either amyloidosis or nigrostriatal impairment, respectively. Readers were then provided in a stepwise fashion with i) T-maps obtained by the univariate single-subject voxel-based analysis (VBA) with respect to a control group of 40 age- and sex-matched healthy subjects, and ii) individual odds-ratio (OR) plots obtained by the volumetric regions of interest (VROI) semiquantitative analysis of the two main hypometabolic clusters deriving from the comparison of MCI-AD and MCI-LB patients in the two directions, respectively.
Results:
Mean diagnostic accuracy of visual assessment was 76.8±5.0% and did not significantly benefit from adding the univariate VBA T-map reading (77.4±8.3%) whereas VROI-derived OR plot reading significantly increased both accuracy (89.7±2.3) and inter-rater reliability (ICC 0.97[0.96-0.98]), regardless of the readers’ expertise.
Conclusions:
Conventional visual reading of FDG-PET is moderately accurate, is not significantly improved by univariate single-subject VBA but by a VROI analysis built on macro-regions, independently of reader skills.