Selection of the control group for VBM analysis: Influence of covariates, matching and sample size

Simultaneous segmentation and grading of anatomical structures for patient's classification: Application to Alzheimer's disease

“…However, the number of training subjects required by SNIPE is similar to the number required by VBM studies. As noted by Pell et al (2008), a group size of 30 to 50 subjects per population is typical in a VBM study while a group size of 70-90 subjects per population is optimal for detection of HC volume loss. In our experiment, we found that 30 subjects from each population is sufficient to provide very high classification rates.…”

Regional Volume Analysis of the Parkinson Disease Brain in Early Disease Stage: Gray Matter, White Matter, Striatum, and Thalamus

“…The ANCOVA with the covariates of age and ICV was used to compare the focal brain volume between groups because age, sex, and ICV were expected to influence volume. 29 A sex effect was absent in the current study because only female participants were recruited. ANCOVA by using covariate age and ICV was applied to compare the volumes of the caudate nucleus, putamen, thalamus, GM, and WM between patients with PD and controls.…”

“…The following methods have been introduced to overcome this problem: inclusion of the covariates in the statistical analyses and selection of controls that matched the patient group regarding demographic parameters 29 (though the relative reliability of the approaches is inconclusive). In the current study, we used ANCOVA as a general linear model to compare groups and attempted to select controls with demographic parameters that matched those of the patients.…”

Focal structural changes and cognitive dysfunction in juvenile myoclonic epilepsy

“…A more recent study investigating a large network of regions implicated in JME using MRS, including the medial prefrontal cortex, primary motor cortex, occipital cortex, and posterior cingulate cortex, further demonstrated decreased NAA in primary motor cortex, medial prefrontal cortex, and reduced GLX to creatine-phosphocreatine ratios (a proxy measure of neuronal excitability) in the posterior cingulate, overlapping with the regions reported here in the VBM analyses. 35 In line with the guidelines of Pell and colleagues 36 on maximization of detection power in group comparison VBM, our control group size varied across analyses. However, a subset of participants was kept constant across all 3 analyses.…”