Vascular lesions and brain atrophy in Alzheimer's, vascular and mixed dementia: an optimized 3T MRI protocol reveals distinctive radiological profiles

Background

Behavioral and psychological symptoms of dementia (BPSD) are a distressful condition. We aimed to investigate the

BPSD distribution in subjects with cognitive impairment, and the potential correlations between BPSD and neurodegeneration in

terms of cerebrospinal fluid (CSF) tau and brain atrophy.

Methods

Seventy-six subjects received a diagnosis of Alzheimer’s (AD=32), vascular (VD=26) or mixed (MD=18) dementia according to Hachinski scale and NINCDS-ADRDA criteria. Three independent raters assessed the brain images acquired according to a high resolution 3T MRI protocol (including 3D FLAIR, T1, SWI and 2D coronal T2 sequences) with semiquantitative scales for vascular lesions (periventricular and deep white matter lesions, PVL and DWML, deep grey matter lesions, DGML, enlarged perivascular spaces, PVS, and microbleeds, MB) and brain atrophy (medial temporal atrophy, MTA, posterior atrophy, PA, global cortical atrophy-frontal, GCA-F, and Evans’ index). The inter-rater agreement was assessed with the intraclass correlation coefficient (ICC).

Results

Raters reached a good-to-excellent agreement for all scales (ICC ranging 0.78-0.96). A greater number of PVL (p<0.001), DWML (p<0.001), DGML (p=0.010) and PVS (p=0.001) was observed in VD compared to AD, while MD showed a significant greater number of PVL (p=0.001), DWML (p=0.002), DGML (p=0.018) and deep and juxtacortical MB (p=0.006 and p<0.001, respectively). No significant difference was observed in scores of cortical atrophy scales and Evans’ index among the three groups.

Conclusion

The use of a high-resolution 3T MRI protocol, including SWI, allowed a reliable and time-saving assessment of vascular lesions and atrophy using dedicated visual scales. Our findings confirm that white and grey matter lesions are the predominant abnormalities in both vascular and mixed dementia, whereas juxtacortical microbleeds predominate in mixed dementia, suggesting that cerebral amyloid angiopathy could be the main underlying pathology.