VBM method protocol
| VBM | Action | Algorithm |
|---|---|---|
| Step 1: preprocessing | Affine register to MNI template; | SPM5* |
| skull strip images; | BET | |
| segment gray matter; | SPM5 | |
| manifold additional affine registration | air, define common air | |
| Step 2: statistics | 1) Simple t test between converters and nonconverters; | SPM5 |
| 2) Model with covariates; condition: conversion or not; nuisance variables: age, sex, global gray matter; NYU; MMSE not included due to significant interaction with NYU; | SPM5 | |
| 3) Reporting of results at P < .1 corrected and anatomic percentages | aal |
Note:—BET indicates brain extraction tool; MNI, Montreal Neurologic Institute; NYU, New York University paragraph recall test; MMSE, Mini-Mental State Examination; aal, automatic anatomic labeling.
* SPM software, versions SPM2 and SPM5.