Measurement of global brain atrophy in Alzheimer’s disease with unsupervised segmentation of spin-echo MRI studies

In 16 patients with probable Alzheimer's disease (AD; NINDS criteria, age range 56-78 years), gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) absolute and fractional volumes were measured with an unsupervised multiparametric post-processing segmentation method based on estimates of relaxation rates R1, R2 (R1 = 1/T1; R2 = 1/T2) and proton density [N(H)] from conventional spin-echo studies (Alfano et al. Magn. Reson. Med. 1997;37:84-93). Global brain atrophy, and GM and WM fractions significantly correlated with Mini-Mental Status Examination and Blessed Dementia Scale scores. Compared with normals, brain compartments in AD patients showed decreased GM (-6.84 +/- 1.58%) and WM fractions (-9.79 +/- 2.47%) and increased CSF fractions (+58.80 +/- 10.37%). Changes were more evident in early-onset AD patients. In AD, measurement of global brain atrophy obtained by a computerized procedure based on routine magnetic resonance studies could complement the information provided by neuropsychological tests for the assessment of disease severity.