Table I.
Neuroimaging studies on the reliability of multicenter VBM
| Design | Subjects | Sequence/imaging analysis tools | Outcome | Findings | ||
|---|---|---|---|---|---|---|
| Phantom studies | (Ewers et al., 2006) | –eleven 1.5T scanners | (n = 1) | –T1‐weighted scans/MPRAGE | multicenter variability | –nine of eleven centers met the reliability criteria of the phantom test, whereas two centers showed aberrations in spatial resolution, slice thickness and slice position |
| Healthy volunteers studies | (Tardif et al., 2009) | –two time‐points; –two different scanners (1.5 and 3T) | HV (n = 8) | –MPRAGE; ‐MNI image processing tools; ‐SPM5 | (1) image quality (SNR/image uniformity); (2) GM density; (3) power analysis for longitudinal and cross‐sectional VBM study | (1) SNR and Image non‐uniformity increased significantly at 3 T; (2) regional biases between protocols in the VBM results, in particular at 3 T; (3) smaller number of subjects required in a longitudinal study to detect a difference in GM density at 3 T for MP‐RAGE |
| (Moorhead et al., 2009) | –three 1.5T scanners; –two time‐points | HV (n = 14) | –T1‐weighted MRI scans; ‐SPM5 (separate sets of tissue priors for each scanner) | (1) intra‐ and inter‐scanner variability | (1) inter‐scanner variability not reduced to the level of intra‐scanner variability (scanner specific priors for SPM assist in pooling of data from different sites) | |
| (Huppertz et al., 2010) | –six different sites; –different vendors; –different field strengths (1.5 and 3T); –three time‐points | HV (n = 1) | –MPRAGE; ‐SPM5 (predefined masks derived from a probabilistic whole‐brain atlas) | (1) intra‐scanner variability; (2) inter‐scanner variability; (3) MPVD | (1) CV per brain structure: median 0.89%; (2) CV: median 4.74% (combined variability: median, 4.80%); (3) MPVD: (for CV results 0.50, 3.78, and 3.80%): 1.4% for the same scanner, 10.5% for different scanners | |
| Patient studies (different states of function and dysfunction) | (Stonnington et al., 2008) | –one site; −10 years; −6 scanners (1.5 T; same platform); ‐multiple upgrades over time | – AD (n = 62); –cognitively normal elderly controls (n = 74) | –T1‐weighted MRI scans; ‐whole‐brain voxel‐wise analysis; –SPM5 | (1) effect of disease; (2) effect of scanner; (3) interaction of scanner and disease | (1) reduction of GM in medial temporal lobe; (2) less than group differences and only significant in thalamus; (3) no significant interaction of scanner with disease group; → results not confounded by scanner |
| (Pardoe et al., 2008) | –three different sites; –3T and 1.5T scanners | –CAE; ‐ HV; n (CAE/controls) = site A) 10/213 site B) 15/33 site C) 19/11 | – T1‐weighted MRI scans; ‐optimized VBM | (1) comparisons of CAE subjects and controls stratified by site; (2) inter‐site comparison of controls from each site; (3) factorial analysis of all data with site and disease status as factors | (1) consistent regions of structural change in the thalamic nuclei; (2) site‐specific differences between controls, which requires adjustment for site in the combined analyses; (3) thalamic atrophy in CAE cases; → combined VBM: consistent patterns of structural change in CAE when site factor in statistical analysis | |
| (Ewers et al., 2006)a | –ten of eleven 1.5T scanners; –six different 1.5T scanners | –HV (n = 1); –AD (n = 73); –MCI (n = 76) | –T1‐weighted MRI scans or MPRAGE; –manual hippocampal volumetry; ‐automatic segmentation of brain compartments; –SPM2/VBM | (1) multisite variability; (2) Power analysis for detection of a difference in GMV between AD and MCI patients across centers | (1) CV: 3.55% (hippocampus); 5.02% (grey matter) 4.87% (white matter); 4.66% (cerebrospinal fluid); 12.81% (± 9.06) voxel intensities GM; 8.19% (± 6.9) WM; (2) (d = 0.42): N = 180; → good reliability across centers | |
| (Schnack et al., 2010) | –four 1.5T scanners, one 1.0T scanner (four vendors); –different acquisition protocols | – HV (n = 6) | −3D‐FFE, SPGR, 3D‐FLASH, MPRAGE; –MNI image processing tools, both for VBM and CORT; ‐development of methods to detect reproducibility of VBM/CORT to detect group differences | (1) group effect; (2) heritability | (1) reliability maps showed an overall good comparability between the sites; (2) scan pooling improved heritability estimates |
AD, Alzheimer's disease; CAE, childhood absence epilepsy; CORT, cortical thickness measurement; CV, coefficient of variation; GM, gray matter; GMV, gray matter volume; HV, healthy volunteer; MCI, mild cognitive impairment; MPRAGE, magnetization‐prepared rapid gradient echo; MPVD, minimum percentage volume difference for detecting a significant volume change between two volume measurements in the same subject calculated for each substructure; MNI, Montreal Neurological Institute; MRI, magnetic resonance imaging; VBM voxel‐based morphometry; SNR, signal:noise ratio, SPM, statistical parametric mapping; 3D‐FFE, three‐dimensional T1‐weighted coronal spoiled gradient echo scan WM white matter.
a
Same publication reports the phantom study above.