Quantitative assessment of brain atrophy in bvFTD: Implications for diagnostic conversion

INTRODUCTION: Brain atrophy increases diagnostic confidence in behavioral variant frontotemporal dementia (bvFTD); however, standardized tools have not been systematically applied. This study evaluated visual rating scales (VRS) to quantify atrophy in a longitudinal bvFTD cohort with differing diagnostic certainties. METHODS: Ninety-three probable and 15 possible bvFTD patients were recruited. Five validated VRS were applied to magnetic resonance imaging scans by blinded raters. Receiver operating characteristic curves and logistic regression examined baseline differentiation and predictors of probable bvFTD. Longitudinal analyses and qualitative case review assessed VRS as predictors of diagnostic conversion. RESULTS: Bilateral orbitofrontal and frontoinsular atrophy differentiated probable from possible bvFTD (areas under the curve > 0.7). Baseline left orbitofrontal VRS strongly predicted baseline probable bvFTD (odds ratio = 3.77, p = 0.002). Converters to probable bvFTD (5/10 cases) had higher baseline left orbitofrontal VRS than non-converters (Mann–Whitney U = 5, p = 0.053). Case reviews supported the quantitative findings. DISCUSSION: VRS enhance diagnostic certainty and may assist in monitoring bvFTD disease progression across clinical settings.