There is limited application of quantitative techniques for the assessment of clinical brain images in neurodegenerative disorders. Early assessment of quantitative differences on MR neuroimaging could be extremely helpful in distinguishing bvFTD from AD.

To evaluate patterns of brain atrophy as measured on volumetric MR neuroimaging in behavioral variant frontotemporal dementia (bvFTD) compared to Alzheimer’s dementia (AD).

We evaluated ten comparably demented patients, 4 meeting International Consensus Criteria for clinically probable bvFTD and 6 meeting diagnostic criteria for Alzheimer’s dementia (AD) of early onset. The clinical diagnosis in both groups was supported by changes on FDG-PET. We then analyzed their volumetric MRI scan 3 Tesla with MP-RAGE sequences. Each MRI had quantification of 45 brain structures with a program called Neuroreader. Each volume was adjusted for the head size, age, and gender and compared to a normative database to compute Z-scores and percentiles. Correlation analysis was done to determine the variation in brain structure between the groups.

There were no statistically significant differences between age and gender in between the bvFTD and AD groups. The patients with bvFTD had significantly smaller thalamic volumes (r = -.82, p = .02), ventral diencephalon z-scores (r = -.79, p = .03), and pallidum z-score (p = -.78, p = .03); whereas, the patients with AD were more likely to have cerebrospinal fluid ventricular expansion (r = -.86, p = .01) particularly in the lateral ventricles (p = -.83, p = .02). There are not statistically significant differences in hippocampal, frontal, or temporal lobar volumes.

We conclude that the regionally specific variations in brain structure between bvFTD and AD patients can be detected on quantitative MRI. This work can be applied towards better diagnostic differentiation of bvFTD from AD early in their course, when current and future interventions may be most effective.