Fractional Anisotropy in Three Variants of Primary Progressive Aphasia

Abstract

Objective: Our aim was to report diffusion tensor imaging (DTI) patterns in three patients, each with a different primary progressive aphasia (PPA) variant. Design: One agrammatic PPA, one semantic PPA, and one logopenic PPA subject underwent a magnetic resonance imaging examination including DTI sequences. The fractional anisotropy (FA) value was calculated in regions of interest (ROIs) involved in these three variants (perisylvian region, temporal pole, and parietotemporal junction) for each patient. Left-right FA ratios in each ROI were compared between PPA subjects and a group of three amnestic mild cognitive impairment patients with a cerebrospinal fluid biomarker profile of the Alzheimer type. Results: The FA values were lower in the left hemisphere (p = 0.03). The lowest FA values were observed in the left perisylvian region for the non-fluent/agrammatic subtype PPA patient, in the left anterior temporal lobe for the semantic subtype PPA patient, and in the left parietotemporal junction for the logopenic patient (p = 0.028). The left-right FA ratio in these specific ROIs for each PPA variant was significantly lower than in the amnestic mild cognitive impairment group (p = 0.009). Conclusion: DTI patterns could be an effective new tool for diagnosing PPA and classifying the three variants.

White Matter Disease Correlates with Lexical Retrieval Deficits in Primary Progressive Aphasia

“…As in other studies assessing DTI within specific PPA variants, the numbers of participating patients were relatively small. Although these groups were larger than those in several previous studies investigating WM in these PPA phenotypes (35, 36, 39), it would be valuable to study larger group sizes to evaluate the TSA technique in a more comprehensive manner. TSA employs data reduction in the direction locally perpendicular to the surface of the tract model.…”

“…Fewer studies have reported FA disruptions in lvPPA. Previous work has described damage to left SLF and WM of the parietotemporal junction (12, 39). One study reported widespread FA reductions in left WM structures relative to controls (36).…”

Neuroimaging Biomarkers of Neurodegenerative Diseases and Dementia

“…13,16,123 DTI studies in logopenic aphasia have also shown atrophic changes, including reduced white matter integrity in the left temporoparietal junction and bilateral (but left > right) inferior longitudinal fasciculus, uncinate fasciculus, superior longitudinal fasciculus, and other subcortical projections. 124,125 SPECT and FDG PET studies have shown reduced perfusion and brain metabolism in the left temporoparietal lobe, respectively. 120,123,126 In addition, a recent study demonstrated increased [11C]PiB uptake in patients with logopenic aphasia, suggesting the presence of significant cerebral amyloid.…”

Particularités du variant logopénique au sein des aphasies progressives primaires

“…Cette technique permet de diffé rencier les APP logopé niques des deux autres variants d'APP et des troubles cognitifs lé gers amné siques due à une neuropathologie de maladies d'Alzheimer, non seulement au niveau du groupe, mais é galement au niveau individuel [77,78]. En effet, dans le cas des APP logopé niques, une atteinte bilaté rale pré dominant à gauche du faisceau unciné , des faisceaux longitudinaux supé rieur et infé rieur, des projections sous-corticales et du ré seau fronto-parié tal est observé e [77,[79][80][81]. Ces anomalies de la substance blanche sont é galement retrouvé es en dehors des zones atrophié es, permettant d'en faire un marqueur pré coce d'entré e dans la maladie [77,80].…”

“…En effet, dans le cas des APP logopé niques, une atteinte bilaté rale pré dominant à gauche du faisceau unciné , des faisceaux longitudinaux supé rieur et infé rieur, des projections sous-corticales et du ré seau fronto-parié tal est observé e [77,[79][80][81]. Ces anomalies de la substance blanche sont é galement retrouvé es en dehors des zones atrophié es, permettant d'en faire un marqueur pré coce d'entré e dans la maladie [77,80].…”