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.