Longitudinal automated brain volumetry vs. expert visual assessment of atrophy progression on MRI is robust but caution is advised

Automated tools have been proposed to quantify brain volume for suspected dementia diagnoses. However, their robustness in longitudinal, real-life cohorts remains unexplored. We investigated if expert visual assessment (EVA) of atrophy progression is reflected by automated volumetric analyses (AVA) on sequential MR-imaging. We analyzed a random subset of 20 patients with two consecutive 3D T1-weighted examinations (median follow-up 4.0 years, LQ-UQ: 2.1-5.2, range: 0.2-10). Thirteen (65%) with cognitive decline, the remaining with other neuropsychiatric diseases. EVA was performed by two blinded neuroradiologists using a 3 or 5-point Likert scale for atrophy progression (scores ±0-2: no, probable and certain progression or decrease, respectively) in dementia-relevant brain regions (frontal-, parietal-, temporal lobes, hippocampi, ventricles). Differences of AVA-volumes were normalized to baseline (delta). Inter-rater agreement of EVA scores was excellent (κ=0.92). AVA-delta and EVA showed significant global associations for the right hippocampus (p=0.035), left temporal lobe (p=0.0092), ventricle volume (p=0.0091) and a weak association for the parietal lobe (p=0.067).Post hoctesting revealed a significant link for the left hippocampus (p=0.039). In conclusion, the associations between volumetric deltas and EVA of atrophy progression were robust for certain brain regions. However, AVA-deltas showed unexpected variance, and therefore should be used with caution in individual cases, especially when acquisition protocols vary.