Multicenter assessment of reliability of cranial MRI.

Clinical utility of magnetic resonance imaging (MRI) for the diagnosis and assessment of neurodegenerative diseases may depend upon the reliability of MRI measurements, especially when applied within a multicenter context. In the present study, we assessed the reliability of MRI through a phantom test at a total of eleven clinics. Performance and entry criteria were defined liberally in order to support generalizability of the results. For manual hippocampal volumetry, automatic segmentation of brain compartments and voxel-based morphometry, multicenter variability was assessed on the basis of MRIs of a single subject scanned at ten of the eleven sites. In addition, cranial MRI scans obtained from 73 patients with Alzheimer's disease (AD) and 76 patients with mild cognitive impairment were collected at subset of six centers to assess differences in grey matter volume. Results show that nine out of eleven centers tested met the reliability criteria of the phantom test, where two centers showed aberrations in spatial resolution, slice thickness and slice position. The coefficient of variation was 3.55% for hippocampus volumetry, 5.02% for grey matter, 4.87% for white matter and 4.66% for cerebrospinal fluid (CSF). The coefficient of variation was 12.81% (S.D.=9.06) for the voxel intensities within grey matter and 8.19% (S.D.=6.9) within white matter. Power analysis for the detection of a difference in the volumes of grey matter between AD and MCI patients across centers (d=0.42) showed that the total sample size needed is N=180. In conclusion, despite minimal inclusion criteria, the reliability of MRI across centers was relatively good.