Fig 1.
Upper rows show corresponding axial slices from CT, T2 and T1 MRI, and fused PET+CT and PET+T1. The two scans were performed 7 days apart. MRI shows a lacunar infarct in the right thalamus not visible on CT. Both MRI and CT were scored as Fazekas 2. Fused FDG PET and T1 MRI show a small metabolic defect in the right thalamic infarct (arrows). Statistical surface projections (lower row) show frontal and parietotemporal hypometabolism more pronounced in the right cerebral hemisphere and also lower uptake in the left cerebellar hemisphere. PET classification changed from neurodegenerative + vascular disease (white matter lesions) to predominantly vascular disease (white matter lesions + strategic infarct). Clinical diagnosis was changed from neurodegenerative to mixed and the finding was considered to constitute major impact (indication for platelet inhibitory drug).
Fig 2.
CT and MRI performed 10 days apart. T2 MRI shows more pronounced white matter lesions (white arrow) compared to CT (Fazekas score 3 vs 2) and demonstrates also widening of perivascular spaces in the basal ganglia (red arrow) often considered a sign of vascular disease (état criblé). T1 MRI showed more pronounced atrophy of mesial temporal lobe compared to CT (upper right panel) scored as MTA 3 vs 2 on CT. FDG PET shows parietotemporal hypometabolism with involvement also of mesial temporal structures (green arrows, upper right panel) suggestive of Alzheimer’s disease. With MRI, classification of PET changed from neurodegenerative disease to neurodegenerative + vascular disease and the clinical diagnosis changed from neurodegenerative disease to mixed dementia. As the change did not prompt change of therapy, but only diagnosis, the change was classified as minor impact.
Table 1.
Demographic and background information.
Table 2.
Radiology and PET reader scores.
Table 3.
Changes in main PET classification from PET/CT to PET/MRI.
Table 4.
Changes in main clinical diagnosis.